I
NFORMATION
T
ECHNOLOGY
Kuppusamy K S Asst Professor Department of Computer Science School of Engineering and Technology Pondicherry University
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Information Technology Contents UNIT I Lesson 1: Introduction to Information Technology 1.1 Information Technology – The definition 1.2 Data Vs Information 1.3 Information Technology - Scope 1.3.1 Computer Science 1.3.2 Communications 1.4 Introduction to the World of Computers 1.4.1 The Hardware and Software 1.4.2 Operations of a Computer 1.4.2.1 Input 1.4.2.2 Processing 1.4.2.3 Output 1.4.2.4 Storage 1.4.3 Common terms in Computers 1.4.4 Making your computer faster 1.4.5 Computer Trends 1.4.5.1 Smaller 1.4.5.2 Faster 1.4.5.3 Cheaper
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1.5 The communications 1.5.1 Simplex Communication 1.5.2 Half-Duplex Communication 1.5.3 Full-duplex Communication 1.6 Computers and Communications 1.6.1 Mobility 1.6.2 Customization 1.6.3 Integrated Services 1.7 Information Technology Usage 1.7.1 Banking Domain 1.7.2 E-learning 1.7.3 On-line reservation Systems 1.7.4 E-governance 1.7.5 E-Commerce 1.7.6 Videoconferencing 1.7.7 Usage of Information technology in Entertainment 1.7.8 Global Positioning Systems
Lesson 2: Information Systems 2.1 Information Classification 2.2 Types of Information systems 2.2.1 Transaction Processing Systems 2.2.2 Management Information Systems 2.2.3 Decision Support Systems 2.2.4 Executive Information Systems 2.2.5 Office Automation System 2.3 Information Systems Development Cycle 2.3.1 Planning 2.3.2 Analysis
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2.3.3 Designing 2.3.3.1 Preliminary Design 2.3.3.2 Detailed Design 2.3.4 Development 2.3.5 Implementation 2.3.6 Maintenance
UNIT II Lesson 3: The Hardware 3.1 Different architectures of Computers 3.1.1 Getting familiar with terminology 3.1.2 Personal Computer 3.1.3 Workstations 3.1.4 Minicomputers 3.1.5 Mainframes 3.1.6 Supercomputers 3.2 Real Time Systems 3.3 Transaction Processing Systems 3.4 Laptop 3.5 Palmtop 3.6 Client Server and multi-tier Architecture 3.7 Input Devices 3.7.1 Character Input Devices 3.7.2 Pointing Devices 3.7.3 Multimedia Input Devices 3.8 Secondary Storage 3.8.1 Floppy Disks 3.8.2 Hard disks 3.8.3 Compact Disks
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3.8.4 Magnetic Tapes 3.8.5 Flash Memory 3.9. Output Devices 3.9.1 Softcopy Output devices 3.9.1.1 CRT displays 3.9.1.2 Flat-panel Displays 3.9.2 Characteristics of Display Devices 3.9.3 Hardcopy output 3.9.3.1 Impact printers 3.9.3.2 Non-Impact Printers 3.9.3.2.1 Ink-Jet Printer 3.9.3.2.2 Laser Printers 3.9.3.2.3 Thermal Printers 3.9.3.3 Plotters
Lesson 4 : Introduction To Computer Networks 4.1 Benefits of Computer Networks 4.1.1 Sharing critical peripheral devices 4.1.2 Easier communication 4.1.3 Software sharing 4.1.4 Searchability of data 4.1.5 Protection of Data 4.1.6 Remote and Grid Computing features 4.2 Types of Networks 4.2.1 Local Area Network (LAN) 4.2.2 Metropolitan Area Network (MAN) 4.2.3 Wide Area Network 4.3 Network Components 4.4 Network Topology
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4.5 Network Protocols
UNIT III Lesson 5 : The Software 5.1 Characteristics of Software 5.2 Classification 5.2.1 Application Software 5.2.1.1 Classification of Application Software 5.2.1.1.1 Horizontal Market Applications 5.2.1.1.2 Vertical Market Applications 5.2.1.1.3 Custom Applications 5.2.1.1.4 Shareware and freeware 5.2.2 System Software 5.2.3 Utilities 5.3 Operating System 5.3.1 Basic Functions of operating system 5.3.1.1 Process Management 5.3.1.2 Memory Management 5.3.1.3 Input / Output Management 5.3.1.4 Disk and File System Management 5.3.1.5 Security 5.3.2 Classifications of Operating Systems 5.3.2.1 Task Count 5.3.2.1.1 Single Tasked Operating system 5.3.2.1.2 Multi Tasked Operating System 5.3.2.2 User Count 5.3.2.2.1 Single User operating systems 5.3.2.2.2 Multi User operating systems 5.3.2.3 Portability
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5.3.2.4 Machine Type 5.3.2.4.1 Desktop Operating Systems 5.3.2.4.2 Server Operating Systems 5.3.2.4.3 Mainframe Operating Systems 5.3.2.4.4 Embedded Operating Systems
Lesson 6: Programming Languages and Packages 6.1 Programming Language – The Definition 6.2 Generations of Programming Languages 6.2.1 First Generation Language (1 GL) 6.2.2 Second Generation Language (2 GL) 6.2.3 Third Generation Language 6.2.4 Fourth Generation Languages 6.2.5 Fifth Generation Languages 6.3 Packages 6.3.1 Spreadsheets 6.3.1.1 Structure of Spreadsheet 6.3.1.2 Applications of spreadsheet 6.3.2 Desktop Publishing Tools (DTP) 6.3.3 Presentation Tools 6.4 Application Areas of Software 6.4.1 Scientific Applications of Software 6.4.1.1 Software Applications in Medicine 6.4.1.2 Software Applications in Engineering and Research
6.4.2 Commercial Applications 6.4.3 Real Time Applications
UNIT IV Lesson 7 : Introduction to Internet
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7.1 The Birth of Internet 7.2 Internet Communication Methodology 7.3 Internet Service Providers 7.4 Internet = World Wide Web? 7.5 IP Address 7.6 Internet Naming and Addressing 7.6.1 Domain Name Systems 7.6.2 Components of a URL 7.6.3 Domain Types 7.6.4 Secure URLs 7.7 Browsers 7.7.1 Popularly used Browsers 7.7.2 Rendering Engines 7.7.3 Internet Explorer 7.7.4 Mozilla Firefox 7.7.5 Safari 7.7.6 Opera 7.7.7 Netscape Navigator 7.7.8 Google Chrome 7.7.9 So, which is the best browser? 7.8 Electronic Mail 7.8.1 E-mail requirements 7.8.2 E-mail Services 7.8.3 Your e-mail address 7.8.4 An e-mail account for you 7.8.5 How to send an e-mail? 7.8.6 Security with e-mail 7.8.7 Other e-mail Services 7.9 File Transfer
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7.9.1 FTP data transfer 7.9.2 FTP demerits 7.10 Bulletin Board System (BBS) 7.11 Introduction to Intranet and Extranet 7.11.1 Setting up Intranet 7.11.2 Advantages of Intranet 7.11.3 Disadvantages 7.11.4 Extranet 7.12 HTML 7.12.1 Structure of a HTML document 7.12.2 Steps for creation of first HTML file 7.12.3 Parts of an HTML document 7.12.4 HTML output 7.12.5 Widely Used HTML tags 7.12.5.1 Title Tag 7.12.5.2 Paragraph tag 7.12.5.3 Bold, Italic and Underline 7.12.5.4 Starting a new line 7.12.5.5 Inserting a horizontal Line 7.12.5.6 Linking to other page 7.12.5.7 Inserting Images 7.12.5.8 Creating Tables 7.12.5.9 Listing Tags 7.12.5.10 Marquee tag 7.12.6 HTML vs. XHTML
Lesson 8: Multimedia 8.1 Multimedia - definition
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8.2 Components of multimedia 8.2.1 Text 8.2.2 Graphics 8.2.2.1 Gif format 8.2.2.2 Joint photographic expert group (jpeg) 8.2.3 Animation 8.2.4 Audio 8.2.5 Video 8.3 Multimedia requirements 8.4 Multimedia applications 8.4.1 Education 8.4.2 Telemedicine 8.4.3 Entertainment industry 8.4.4 Virtual reality 8.5 Multimedia – challenges
UNIT V Lesson 9: Object Oriented Systems 9.1 History of Object Oriented Systems 9.2 Object Oriented Vs Object based languages 9.3 Object Oriented programming concepts 9.3.1 Objects 9.3.2 Classes 9.3.3 Encapsulation 9.3.4 Inheritance 9.3.4.1 Single level inheritance or simple inheritance 9.3.4.2 Multi level inheritance 9.3.4.3 Hierarchical inheritance 9.3.4.4 Multiple inheritance
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9.3.4.5 Hybrid Inheritance 9.3.5 Polymorphism 9.3.6 Instance 9.3.7 Access Modifiers 9.3.8 Constructors 9.3.9 Destructors 9.3.10 Abstract Classes 9.3.11 Static members 9.3.12 Friend functions 9.4 Object Oriented Database Management Systems 9.5 Object oriented design process 9.6 Advantages of Object Oriented Systems over traditional systems 9.7 Issues with Object oriented systems
Lesson 10 Enterprise Computing and Mobile Computing 10.1 Enterprise Resource Planning 10.1.1 What does ERP means? 10.1.2 ERP and various departments of the organization 10.1.3 Why ERP? 10.1.4 What ERP is not? 10.1.5 ERP is costlier 10.1.6 ERP activities or steps 10.1.7 Extending ERP 10.1.8 ERP critical factors 10.1.9 ERP advantages and disadvantages 10.2 Mobile Computing 10.2.1 Major components 10.2.1.1 Mobile devices 10.2.1.2 Wireless networks
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10.2.2 Cellular network 10.2.2.1 Technologies associated with Mobile networks 10.2.2 Advantages and disadvantages of Mobile computing
Lesson 1: Introduction to Information Technology Introduction
Information technology has made tremendous impacts in the day today life of every human being.
Knowingly or unknowingly everyone is using Information technology in one way or another.
This lesson would provide an introduction to this fascinating field called Information Technology.
Objectives The objectives of this lesson are as listed below: 1. Defining the term information technology 2. Differentiating Data and Information 3. Providing an insight in to scope of Information technology. 4. Introducing two important components of computers (software, hardware) 5. Explaining various operations of computer (input, processing, output, storage ) 6. Proving some useful tips to make your computer faster. 7. Explaining various trends in design of computers 8. Providing an insight into the various types of communications
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9. Highlighting the advantages of integrating computer science and communications 10.
Explaining the applications of Information technology in various
works of life.
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1.1 Information Technology – The definition The term information technology can be defined as follows: “Information technology is a common term that includes any technology that is used to store, retrieve, delete and communicate information”. In other words it is the technology used to manipulate information. Today we are living in a world which is overflowed with information. So there is a need for technology that would handle this information in an effective manner. Information technology is the solution to the above problem.
1.2 Data Vs Information At this point you may have a question about the difference between data and information. The following lines define data and information.
Data is a raw fact. Data doesn't associate any specific meaning with it. For example “New Delhi” may be considered as data by which you don‟t get any meaning.
Information is the result of data processing. In other words, processed data is called information. If you consider the same example which is quoted for data then “New Delhi is the capital of our country” is the information. This information has got an associated meaning. So before proceeding any further you should remember the basic fact
that information and data are not interchangeable terms. So information technology focuses at information rather than simply data.
1.3 Information Technology - Scope Information Technology is not a single stand alone technology. Indeed it is a combination of more than one technology. Two important components of Information technology are
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Computers
Communications
1.3.1 Computer Science As stated earlier information technology needs inputs from the external world. The computers are used to accept data and process them into meaningful information. So the process of conversion from data to information happens at computers. The raw data many not be used effectively. To make the effective use of it, data has to be processed in to information. The growth in computer technology is a must for the growth in information technology. Faster the information processed at the computer, lesser the delay in making it available to the user. 1.3.2 Communications Information technology is not only computer science. One more critical component is the communication technology. While defining information technology it was stated that communication of information is also a role of IT. To transfer information from one place to another you need communication technology. The communication technology has reduced importance of the physical distance. Nowadays it is not important that how far away you are from the person whom you want to contact, provided that you have the technology. Internet has really made the world as “global village”. So the role of communications in information technology is crucial.
1.4 Introduction to the World of Computers Computers are playing a key role today in all fields of work. So it becomes ultimately necessary to get an insight into the world of computers.
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Computers are general purpose machines which can be adopted for your usage by installing specialized hardware and software. Computers are based on digital technologies. This section would highlight on the important concepts in computer science. 1.4.1 The Hardware and Software The two important components of computers are hardware and software. To make the computers efficient, proper hardware and software has to be identified and installed. The electrical, mechanical, electronic components of computer is called hardware i.e. all the hardware are physical entities. Examples for hardware are as listed below:
Keyboard
Mouse
Microprocessor
Motherboard etc
Software is logical component of the computer. Without installing the right software your computer would become idle. Examples of software as listed below:
Operating systems
Packages
Utility programs etc
In the case of software there exist different types of it. The general classification is as listed below:
Application Software
System Software
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Application software is used to solve a particular problem. For example software used in the banking domain is an example for application software. At the same time system software are used to make the effective use of computers. For example operating systems are systems software. No one buys a computer to simply work with operating systems but it is the operating systems which make the usage of computers smoother. Today you can't even think of a computer without an operating system. Because operating systems provides you such a level of abstraction so that the users need not to worry about any internal working principles of the computer. The computers used in various fields have certain components in common. At the same time they have specialized components also. For example a computer used with retail shops would have a barcode reader connected to it. 1.4.2 Operations of a Computer Though the computers used in different fields have different purposes, there are certain operations which are common across all these domains. These operations are as listed below:
Input
Processing
Output
Storage
1.4.2.1 Input Input is the operation of feeding data in to a computer. Input is the starting point in operations of computers. There exist various kinds of devices used to provide input. They are
Keyboard
Mouse
Scanner
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Webcam etc
Input can be text, image, audio, video etc. For example Keyboard is the device used to provide text input. Similarly scanner is a device for image input. These input devices are discussed (in terms of their usage, working principle etc) in detail in later portions of this text. Generally input devices are called peripheral devices because they are connected to the computer through various ports like serial port, USB etc. 1.4.2.2 Processing The core part of computing is the processing. To perform this processing task you have the “Microprocessors”. Microprocessor is a smaller sized chip containing large number of electronic circuitry inside. In fact the microprocessor is the Central Processing Unit (CPU). At times the cabinet is mistakenly called as CPU but it is not. The speed of CPU is measured in terms of Hertz. As of today (October 2008), the commonly used processors have a speed of 3 GHz (Giga Hertz) or similar. Using multiple CPUs for a desktop computer is becoming popular nowadays. You would have heard of CPUs with label Dual core, Quad Core etc. Dual core has two processors in them where as Quad core has four processors. Usage of more number of processors would definitely speed up the computers because of the fact that tasks can be shared among those processors. (Another point to remember here is speed of computer does not only depend upon the speed of microprocessor but upon various factors like amount of main memory etc). There is a component in computer which is called the “Motherboard”. It is the motherboard which is holding the entire components together. The CPU, the main memory and all other components are installed on mother board. The mother board can be compared with the central nervous system of the human
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body. (In terms of their role in establishing communication and coordination between various parts of the system they are similar). 1.4.2.3 Output The result of processing has to be given to users which is the ultimately purpose of using computers. The output unit performs this task. There exist various output units available as listed below:
Monitor: It is the primary output device associated with the computers. The CPU sends the signals to an electronic circuit called “Video Card”. It is the video card which acts as the interface between monitor and the CPU. The display quality depends on the quality of video card as well. There exist various types of monitors.
Cathode Ray Tube (CRT)
Flat panel display etc
Printers: Printers are used to produce the hardcopy output. There exist various types of printers as listed below:
Impact Printers
Non-impact printers
Audio output: To produce audio output speakers are connected to the system. In case of audio output also you have a hardware called “Sound Card”. This sound card acts as an interface between speakers and the CPU. The quality of audio depends both on the quality of speakers and the sound card‟s quality.
1.4.2.4 Storage Another important component of a computer is the storage. Primarily there are two types of storage. They are
Volatile Storage: When the power is disconnected the contents would be erased.
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Non-Volatile Storage: Even after the power supply is disconnected the contents would be retained.
The capacity of storage is measured in terms of a unit called “bytes”. The below list gives various hierarchies in the storage unit:
8 bits
- 1 Byte
1024 bytes
- 1 Kilo Byte (KB)
1024 KB
- 1Mega Byte (MB)
1024 MB
- 1 Giga Byte (GB)
1024 GB
- 1 Terra Byte (TB)
The above list is not complete. The unit goes beyond TB also. But those are not commonly used in general purpose computers. In the case of non-volatile storage, there exist various types of technologies as listed below:
Magnetic Storage: Based on the magnetic principles. Examples for such devices includes
Hard Disks
Floppy Disks etc
Optical Storage: Based on the optical principles. Examples for such devices includes
Compact Disk (CD)
DVD (Digital Versatile Disk) etc
Semi-conductor memory: Here electronic circuits are used to store the contents. Examples for such devices include pen drives etc. They are based on EEPROM technology.
In this section various units are outlined. The detailed explanations of individual units are given in later portions of this text. But the above introduction would be an eye-opener to understand the concepts in detail given in later portions.
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1.4.3 Common terms in Computers There exist certain common terms in computers. This section would throw light on those common terms.
BIOS: The Basic Input Output System is called BIOS. It is the BIOS which holds the all the settings associated with the computer components. BIOS is the fundamental unit of a computer (IBM PC and clones). Through BIOS you can make certain crucial changes which would improve the system performance. At the same time care should be taken while interacting with BIOS because wrong settings would create some critical flaws.
Ports: To connect any peripheral devices the ports are used. There exist many types of ports as listed below:
Serial Port
Parallel port
USB port.
Formatting: It is the process of making a storage device ready to use. A file system would be created during formatting. Formatting would erase all the data in that partition.
Defragmentation: To make the disk access faster, all the used portions would be aligned together. So that free memory would be aligned separately. This process is called defragmentation. It is advisable to perform defragmentation at regular intervals so that your computer speed would improve.
Installation: Installation is another term which is repeatedly used in computers. Installation is the process of incorporating software into the computer. Installation is different from copying. If you simply copy, most of the software won‟t work.
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1.4.4 Making your computer faster Every one wants their computer to work faster. How can you make your computer to work at its optimal speed? Below given is a list of tips for doing that.
Do not install any unnecessary software in to your computer. This would definitely save your hard disk space. Many software may be doing some operations in the background i.e., with out the knowledge of the user. If you have such software in your system which you are not using but they are occupying your memory and processor, certainly the system would become slower. So it becomes vital not to install any unnecessary software in to your system.
Defragmentation of disk at regular intervals would make the disk access faster, thereby improving the overall performance.
Higher rpm disks would be faster. For example the speed of 7200 rpm (revolutions per minute) would be far better than the 3000 rpm disk. So choose a disk with higher rpm.
Protect the system from virus attacks. Though the antivirus program can make your system little bit slower but the benefits you get from those programs are huge.
Usage of good amount of RAM (Random Access Memory) is another way to make your system faster. Most of the software nowadays requires higher amount of RAM i.e., main memory. If you want to use those types of software then you have to provide adequate amount of RAM to your system.
Choice of motherboard and processor should be appropriate. If you choose otherwise, the system speed would become lesser. Especially motherboard selection is a vital process. If you choose an inappropriate motherboard then what ever may be the quality of other components, the performance would be lesser.
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Installation of an operating system depends on your needs and the hardware configuration of your system. There is no compulsion that you should always use high end operating systems. The choice of operating system is major factor for the speed of your computer.
By keeping the above factors in mind you can certainly make your computer faster. From the above list you would have understood a fact that the speed depends upon both hardware as well as software. While trying to make your computer faster equal attention has to be given to both the components. A computer with a good hardware configuration can also be slower due to the above mentioned software reason. The vice-versa is also true i.e., a properly built software would also work slower if optimal hardware is not used. The speed of microprocessor is many folds faster than the peripheral devices like disk. So the bottleneck is at the place of disk access. This disk access bottleneck can be addressed by following the points mentioned above (using a higher rpm disk, increasing the amount of RAM (main memory)) Turning on all the graphical features (like animation options, shadows etc) can make your system slower if adequate amount of main memory is not there. So never turn-on this features when your system configuration is lesser to support that. 1.4.5 Computer Trends In designing the computers the trend that is adopted is three fold. They are
Smaller
Faster
Cheaper
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1.4.5.1 Smaller Computers were very huge in size in the past. The first generation computers were largest in size. With each generation the size of the computer is getting reduced. The reason for this is the improvements in the electronics field. Many advanced technologies were developed to fabricate huge electronic circuits in smaller size. Nowadays the concept of invisible computers (!) is also getting popular. Invisible in the sense they are hidden within other equipments. For example the washing machines that you use may have microprocessors inside. The smaller size of computers is a factor which has made this possible to implant them inside other equipments. 1.4.5.2 Faster In contrasting with the size the speed is constantly increasing with each generation. Nowadays the speed is measured in Giga Hertz (GHz). Even the desktop PCs today are comparatively faster. Indeed the boundary between the PCs and workstations is blurred nowadays. 1.4.5.3 Cheaper One of the critical factors that have made computers so popular is the reduction in their cost. When the computers were introduced no one thought of using computers to this level of personal purposes. The reduction of cost factor has made the computers to reach every corner of the globe. Constant efforts are going on to make them even cheaper so that everyone can afford to use the computes personally. The above given paragraphs characterizes the trend in the computer world.
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1.5 The communications As we stated earlier another component of IT is the communication. Now the communication has gone to the level so that the distance doesn't matter anymore. In communications there are basically two modes on the basis of connection type. They are
Wired Communication
Wireless Communication
In the case of wired communication a physical connection would exist. In case of wireless communication the physical connection is not there. Wireless communication is well suited for mobile devices. More on this is given in the later portions of this text. The communication can also be classified in to three types on the basis of direction of communication. They are
Simplex Communication
Half-duplex Communication
Full-duplex Communication
1.5.1 Simplex Communication In the case of simplex communication, the mode of communication is only one way. A well known example for this type of communication is the radio. In radio the broadcasting station would send the signals so that the radio set that you have would receive these signals. Your radio set will not have the capability to communicate with the radio station. In other words it can‟t send data back to the sender. This type of communication is called simplex communication.
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1.5.2 Half-Duplex Communication Half-Duplex is an improvement over the simplex communication. In half-duplex communication both the parties involved in the communication process can send and receive but not at the same time. For example the communication devices that you would have seen with a traffic police are examples for half-duplex communication. In that device you can receive signals as well as send signals. But he/she can't do both the things at the same time. 1.5.3 Full-duplex Communication In the case of full-duplex communication sending and receiving signals at the same time is possible. It is the advancement over half-duplex communication. For example the telephones are an example for full-duplex communication. In telephone both the parties can send and receive signals at the same time. Full duplex communication is technically better than other two modes. The modes of communication have to be selected in accordance with the need. 1.6 Computers and Communications To link computers with the public telecommunication network there is a need for a specialized device. Because both these operate using different technologies i.e., digital and analog. The device which acts as an interface between these two is called Modem. The role of the modem is to convert the digital signals into analog and vice versa. A modem can be either internal or external. When the modem is placed inside the cabinet itself, it is called internal modem. When you have modem as a separate unit it is called external modem. Nowadays many of the motherboard
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has an on-board modem. An on-board modem would be an integral part of the motherboard itself. There are three important developments when the computer and communication industry merges together. They are as listed below:
Mobility
Customization
Integrated Services
1.6.1 Mobility Mobile plays a key role in the success of information technology. The ability to access the services on the move is an important development. The mobility has become a reality because of the developments in both computer industry and communication field. The size of the computers becoming smaller has encouraged mobility. With respect to communication, the advancement in wireless communication like cellular networks has contributed largely to this. 1.6.2 Customization The services provided have become customizable. You can select the services according to your needs. For example in the mobile phone industry, various providers are providing services that you can select according to your need. There would be various packages among which you can select one suitable to your needs. 1.6.3 Integrated Services Another important development is the integrated services. Many services are available on a single channel. For example the devices like PDA (Personal Digital Assistants) have the capability to act as a computer, mobile phone etc. So by using such a single device you can compute, access internet, make calls as you wish.
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1.7 Information Technology Usage Information technology has got its usage all fields of life. It is now hard to identify any single field where application of Information Technology is not there. It has got its massive applications in all fields. This section would discuss prominent uses of information technology. Providing a complete reference of all the usages of Information Technology is out of scope of current text. 1.7.1 Banking Domain Banking is certainly one such domain where IT has made tremendous impacts. Following is a list of usages that IT has got in the banking domain: The facility of “Core Banking” has become possible because of Information Technology. Core banking enables the account holder to operate his/her account from any branch. The account holder is not required to go to the specific branch where he/she is holding the account. Core banking has become possible because of the improvements in both Communication industry as well as computer industry. Communication industry has helped in terms of establishing the networking between all the core banking enabled branches. The network that would be established here should be much safer because all the transactions involved are personal. The data flowing through this network should not get hacked by others. The computer industry has helped in terms of providing powerful servers and clients. In the case of banking domain all the sensitive data would be stored in the server. These servers would be maintained by specialist in the field of information security. These servers have to be guaranteed for maximum uptime (the accessible time). Apart from these powerful servers, there are other equipments which are used in the banking domain.
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For example there would be certain specially designed printers to print certain items. Apart from Core banking, now many of the banks provides services like
Mobile banking
Net banking
In the case of mobile banking you would be able to access your account from your mobile device. To provide security passwords would be provided. Almost all the banks provide the facility to access your account over World Wide Web. By using this facility the account holder can operate his/her account from anywhere in the world. Using the net banking facility you can provide payment to many other services. One of the crucial things that you have to take care while using the facilities like mobile banking, net banking etc is that you should keep the password to access these services safer. It is a good practice to change the passwords at regular intervals of time so that the possibility of the password breaking would be reduced. 1.7.2 E-learning E-learning is another massive application of Information technology. Most of the institutions provide e-learning facility nowadays. There exist many advantages of e-learning. E-learning is the process of using information technology to make the teaching-learning process an effective one. E-learning can provide a web based interface. In such a case the scope or area of coverage becomes huge. Because using such a web based interface has very minimal requirement on the client side. The advantages of e-learning are as listed:
Learning materials are accessible from anywhere.
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Incorporation of multimedia into e-learning makes the teachinglearning process effective.
The learning is not restricted to particular time. In case of traditional learning you have to be present at the lecture hall at the specified time to attend the lecture. In the case of e-learning you can select your own convenient time. This would be very helpful in case of people who are in a job.
E-learning in combination with Distant Learning would make the distant learning more interactive. In addition with physical books the econtents can also be given to the learners.
Interactivity can be incorporated easily in to e-learning. The interactivity is possible by means of forums, chat, blog etc.
Improvements in the communication industry have made e-learning smoother. In other words nowadays the bandwidth provided for internet access is generally sufficient enough to access these e-learning materials with multimedia content.
E-learning is a global scale phenomenon. If the learner has got a web browser in his/her system that would be
sufficient enough to access the e-learning materials provided through World Wide Web. Nowadays there exist facilities to access these e-learning materials from devices like mobile phones etc. The provisions can also be made to download the contents to their local machine so that the learner would be able to go through the content even when internet connection is not there. All these facts have made e-learning an effective method of providing knowledge to the learner.
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1.7.3 On-line reservation Systems On-line reservation systems are another important usage of information technology. The term on-line is generally associated with internet. If a particular service is accessible through internet it is called on-line. There exists various on-line reservation systems exists today. Few of them are listed below:
Railway Reservation Systems: The railway reservation system has become very popular nowadays. There is no need to wait in the long queues for booking your tickets. You can do that simply sitting in front of your computer with internet connectivity.
Hotel Room reservation systems: Many hotels provide the facility to book the rooms in advance through internet. By using this facility the trip can be planned very easily.
Airline reservation systems: These systems are very similar to the railway reservation systems.
All these reservation systems involve some sort of money transactions. These transactions can be done through more than one method as listed below:
Payment using net banking facilities
Payment through credit cards
While you pay the money through the net banking facility the bank would be contacted before making you the allocation. The credit card processing also involves very similar techniques. These on-line reservation systems are very effective to plan your activities earlier itself.
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1.7.4 E-governance In a country like ours where the population is huge, the government offices would be accessed by large number of people. To make the services easily available the e-governance concept can be used. E-governance is the process of using information technology to provide the services rendered by a government to the citizens effectively. There are many areas which the e-governance covers. Below given is the list of few services:
Applying nativity / residence certificates etc.
During the purchase of a property like land, the details can be easily accessed if they are computerized.
Paying tax through on-line facilities.
E-governance provides various advantages as listed below:
Services can be accessed easily
The delay in getting the service is reduced.
The services rendered can be made transparent.
Record of services rendered can be maintained effectively so that when the need arises at a later point in time they can be easily retrieved.
The services are not time bound. (You can access the services at any time provided the server in which the service is hosted is up and running)
In case of documents where the scanned copy is available they can be retained forever. The physical documents would be easily damaged as the time progresses. But the scanned documents would not get damaged as the time progresses. They can be easily printed in to hardcopy through printers at any time.
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The above given are the advantages of services provided by egovernance. At the same time there are certain challenges also. The services which are sensitive in nature have to be made much secure. 1.7.5 E-Commerce E-commerce has changed the way in which people purchase and sell items. The customer can access the e-commerce service with the help of a web browser and internet connectivity. E-commerce is the process of using information technology to carry out commercial activities. E-commerce provides various advantages as listed below:
E-commerce is a global scale phenomenon. So the market base of the company is out of bounds of any single nation. To perform the same otherwise is very difficult and costlier.
When number of e-commerce services are there, you can easily compare the products from various sellers before buying. Through this a product can be purchased at a minimum possible cost.
You can directly purchase items from world class sellers. For example in case of book and other materials there are various popular e-commerce services exist. So whenever a particular book or material is not available in your geographical location you can use these e-commerce services to get them from any part of the world.
E-commerce employs many secure technologies. So nowadays it has become comparatively secure.
You can easily track your orders. Many e-commerce sites provide this option of tracking your order i.e. you can easily find out the current stage of your order.
E-commerce is getting applied in more and more number of fields. Starting with very cheap items to costliest items are now available through ecommerce. It is the e-commerce which has added the commercial touch to
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World Wide Web which is one of the important reasons for such a mammoth growth of World Wide Web. 1.7.6 Videoconferencing With the help of videoconferencing you can communicate with a person independent of his/her geographical location, as if he/she is sitting in front of you. Videoconferencing involves multiple media of data like audio, video etc. The videoconferencing is also called teleconferencing. There exist many advantages of videoconferencing. Some of them are listed below
In the case of telephonic communication you cannot see the facial expressions and gestures made where as it is possible in videoconferencing.
No physical movement is required. If a conference involves experts from far away locations then the distance to be traveled would be very huge. But in the case of videoconferencing these travel time is therefore saved.
Since the videoconferencing involves real-time transfer of video from one location to another it would require higher bandwidth. Primarily there are two types of videoconferencing based on the number of participants. They are
Point-to-point videoconferencing which involves only two persons.
In the case of multipoint videoconferencing more than two participants can involve in the conferencing process.
Nowadays a recent trend which is coming up is called “webminars”. A webminar is nothing but web based seminars. In a web based seminar
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(webminar) participants can be from any part of the globe provided they have a system with internet connectivity. 1.7.7 Usage of Information technology in Entertainment Apart from the serious usages of information technology, it has got of many applications in the entertainment fields also. Usage of Information technology in movies is well-known. In movies many special effects are made by the application of information technology concepts like graphics and animation. Apart from these special effects there are movies which are totally created with the help of animation features. To perform these kinds of tasks there are specialized software. That software would have options for drawing, adding effects etc. Not only the visual effects, there are applications associated with music or sound also. There are many music synthesizers and other concepts to add special effects to music. Other than movies the application of information technology in sports is also tremendous. For example in sports like cricket there are multi-folded applications of Information technology. Some of them are as follows: tracking the movement of balls, complete analysis through statistics, ball speed measurements etc are well-known examples of information technology in cricket. It is not only cricket but there exist many other sports like tennis, football, baseball etc where the information technology has introduced many techniques which has made those sports more attractive and entertaining. Information technology is also be used in many sports training sessions. It is used to analyze the actions of players so that the problems identified can be rectified in the later games.
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Information technology has really raised the quality of the final product both in movies as well as in sports. Information technology has introduced many new concepts in those fields as well as enriched many existing processes. For example many of the existing processes which were time consuming have become faster with the application of information technology. 1.7.8 Global Positioning Systems Global positioning system (GPS) is one of the popular applications of information technology. GPS has got its application in various fields. Popular among them are listed below:
GPS can be used to track vehicles. Their position can be tracked from a central location. This vehicle tracking facility has got application in ambulance tracking, fire engine tracking etc.
In the field of geology, GPS is used to identify small changes in the earth surface for further analysis.
GPS is also used to track animals. By using this technology their position can be identified easily.
Satellite imaging facility is used in locating the areas where fishes are available in abundance. This information would be very much helpful for fisherman.
GPS has got applications in military also. The complete description of working principle of GPS is out of scope of
this text. But in an outline, GPS requires number of satellites and many ground stations. These satellites and ground stations will communicate with each other so that the required information is tracked. The above list of applications of GPS is not complete. Apart from the above given applications there are many applications of GPS in various fields. Though the fields change the fundamental technology remains the same.
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Summary
Information technology refers to group of technologies that deal with handling of information.
Data refers to simple fact; Information refers to processing data. Information has a meaning associated with it.
Information technology consists of two major fields called computer science and communications.
Computers are general purchase machines that are used in all the fields.
Various operations of computers include input, process, output, storage etc
Software refers to the logical entities of the computer system.
Hardware refers to the mechanical, electrical and electronic components of computer system.
Speed of computers can be increased by various measures like installing only the necessary software, using hard disks with higher revolutions per minute (rpm) etc
The trends of computer design are three folds: smaller, faster and cheaper
Communication can be either wireless or wired.
Communication can happen in three modes: simplex, half-duplex and full-duplex.
The combination of computer and communication gives us various advantages: customization, mobility and integrated services.
The applications of information technology are in most of the fields. For
example
banking,
e-learning,
e-commerce,
e-governance,
entertainment industry, geographical positioning systems etc.
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Self-assessment Questions Part I (Multiple Choice Questions) 1. Processing of data gives (a) database (b) information (c) security (d)All of the above (e) None of the above 2. Which of the following is used in first generation computers? (a) Flash memory (b) USB ports (c) Vacuum tubes (d)All of the above (e) None of the above 3. Which of the following is not a wireless communication technique? (a) Bluetooth (b) Infrared (c) Wi-Fi (d) Blue rays (e) None of the above 4. The characteristics of mobile computers includes (a) battery mode operations (b) Wireless communication technology (c) hand-held devices (d) all of the above (e) none of the above
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5. “rpm” stands for (a) revolutions per minute (b) rate per movement (c) rank past mobiles (d) all of the above (e) none of the above 6. Interface between CPU and display is called (a) display channel (b) video channel (c) video card (d) all above the above (e) none of the above 7. Identify the odd item (a) USB (b) Serial (c) Parallel (d) EEPROM (e) DMA 8. Which of the following is not an e-payment method? (a) Credit card (b) Net banking (c) master banking (d) all of the above (e) none of the above 9. GPS stands for
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(a) Global Positioning System (b) Graphical Processing System (c) General Pricing System' (d) All of the above (e) None of the above 10.
The advantage(s) of e-commerce is/are
(a) global scale (b) easier to access (c) wide range of options (d) all of the above (e) none of the above Part II (Short Questions) 11.
Write short notes on data and information.
12.
List out modes of communications.
13.
List out any 4 input devices
14.
How hard disk is impacts speed of the computer?
15.
What you mean by “integrated services”?
16.
What is core banking?
17.
List out the advantages of e-governance?
18.
What are all the advantages of e-learning Part III (Detailed Answer questions)
19.
Explain in detail about the advantages of computers and communication
technologies? 20.
Elaborate on various usage of Information technology.
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Answer Key Part I 1. b
2. c
3. d
4. d
5. a
6. c
7. d
8. c
9.a
10. d Part II
11.
Data is simple fact. Data doesn't possess any meaning. The processed
data is called information. Information has a meaning associated with it. 12.
In terms of medium of communication it can be classified in to wired
and wireless communication. In terms of the direction of communication it can be categorized in to simplex, half-duplex and full-duplex communication. 13.
There exist many inputs devices. Four of them are listed here: a) Keyboard b) Mouse c) Webcam d) Touchpad
14.
The rpm (revolutions per minute) of the hard disk decides how fast the
hard disk will work. Since the hard disks are considerably slower than the CPU, an higher rpm hard disk can make the speed of the computer faster. 15.
As a result of merging the computer and communication industry
together you can get various benefits. One of those benefits is the “integrated services”. Many services can be accessed using a single channel or device. This process is referred as integrated services. For example the mobile
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phones can be used for voice communication as well as for surfing the internet. 16.
Core banking refers to the ability to access bank account from any of the
branches of that bank. Core banking is one of the major advantages that banking industry has got from information technology. 17.
The advantages of e-governance include the following a) The services can be obtained without much delay. b) The process becomes transparent comparatively. c) Since the transactions are recorded in the electronic form they would not get affected by the time factor (traditional documents would get damaged as the time progress).
18.
The advantages of e-learning are as listed below a) e-learning is a global level phenomenon b) E-learning is not time restricted. c) Usage of multimedia is e-learning is easier and effective
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Lesson 2: Information Systems Introduction
All the application areas of Information technology discussed in the previous lesson deals with whole lot of information.
Nowadays Information Systems have become an integral part of any organization because no organization can function without information.
Information systems make the organization to function effectively by handling information in an efficient manner.
Starting with a simple retail shop to a multinational organization, Information is everywhere. Of course quantity of information may vary but the usage of information is certain.
Information systems are used to provide necessary information to the organization so that effective decisions can be taken.
Objectives
Introducing various types of information.
Explaining various information systems like transaction processing system, management information system, decision support systems, executive information systems etc.
Providing details about System Development Life Cycle (SDLC).
Explaining each stage of system development life cycle in detail.
2.1 Information Classification The information associated with an organization can be classified in to various categories. Those categories are as listed below:
Operational Information: The type of information which is needed for an organization in a day-to-day manner so that it can function effectively. For example the retail billing associated with a general store is operational information. Operational information doesn't
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need any complex processing to obtain. At the same time the volume of operational information would be larger in nature because they are collected in a day-to-day basis.
Tactical Information: This type of information is helpful during short-term decisions. For example in a retail store, the speed of sales of each item is tactical information. Tactical information is not straightforward. To obtain tactical information, you need operational information. This tactical information is a kind of summary that is generated on top of operational information.
Strategic Information: Strategic information is helpful during long term decisions. The strategic information is very less in volume. They require lot of processing to obtain. Strategic information is handled by the top level management.
Each category of information would be handled by specific level of management. For example operational information is handled by low level management, tactical information by middle level management and strategic information is handled by the top level management. Apart from these there is certain type of information which would be handled by all across the organization. For example the office automation systems would be handled by every one in the organization.
2.2 Types of Information systems In parallel with the type of information there exist various types of information systems. Each information system has a specific purpose and they would be handled by specific levels of management. Various Information Systems are as listed below:
Transaction Processing Systems (TPS)
Management Information Systems (MIS)
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Decision Support Systems (DSS)
Executive Information Systems (ESS)
Office Automation Systems (OAS)
Let us discuss each type of information systems in detail. 2.2.1 Transaction Processing Systems A transaction processing system is for handling the transactions of an organization. Transactions are nothing but routine business activities. These transactions have to be recorded. For example in a retail store, each sale can be considered as a transaction. This sales information has to be tracked for further processing. Transaction processing systems primarily handle the data associated with any organization but they would not produce any complex information from those data. They primarily take care of the operational data associated with an organization. A transaction processing system is an Information system which is used to record all the day-to-day transactions of an organization. The following list is a set of characteristics of a Transaction Processing System.
The Transaction Processing System has well defined input and output. For example in a retail store the point of sale (POS) would gather data about each sale. It has to produce the output in the form of bills.
Transaction processing systems consumes large amount of data. Transaction processing systems are taken care by the low level management.
In an organization each department can have their own individual transaction processing systems. For example purchase department can maintain a TPS; finance can maintain their own TPS etc.
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The Transaction processing systems provide input to the other information systems like decision support systems etc.
Transaction processing systems are very much necessary for smoother operation of an organization in a day-to-day manner. 2.2.2 Management Information Systems Management Information systems occupy the next level hierarchy to the Transaction Processing Systems. A Management Information System gets the input from the transaction processing system and they produce reports which can be used by the managers to carry out various types of activities. Management information systems involve more processing than the transaction processing systems. The management information systems' characteristics are as listed below:
Management information system would be used by the middle level managers in general.
Contrasting to transaction processing system, the management information systems cover various departments of the organization.
As stated earlier management information system's input is from the transaction processing system.
The output of the management information system is in the form of reports. These reports would be used by the middle level management to carry out the business effectively.
Management information system produces various kinds of reports which are as listed below:
Periodical reports: These reports would be generated at regular intervals. For example the daily, weekly,
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monthly and annual reports are examples for periodical reports.
Summary reports: Summary reports would be helpful in finding out various patterns across the data.
Exception reports: These exception reports which provide information about things that are not happening comparing to a normal scenario.
So these management information systems play an important role in the success of an organization. At one end they have links with the low level management as input and they provide useful information for the middle level management for better performance. 2.2.3 Decision Support Systems One of the widely used information systems is the decision support systems. The decision support systems provide the facility for an organization to find out the possible future course of events and carry out activities based on these analyses. The below given list characterizes a decision support system:
The decision support systems are used by the middle level management.
What a manager gets from a management information system is the summary of data but the decision support systems provide analysis of the data which is more important than simply the summary.
At the highest level decision support systems would become very similar to an AI (Artificial Intelligence) based agent.
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To establish decision support system an organization should have well established transaction processing system and management information system.
Decision support systems are based on mathematical models. Using these mathematical models the managers can simulate certain activities. By that they can check out various different parameters and their relationships. Another benefit would be that the managers can prepare themselves for actions when the same future occurs which they tried out during simulation.
Decision support system receives input from most part of the organization. At the same time they receive inputs from external world also. For example the current market trend, the laws introduced by the government etc because all these items can affect the future course of actions of the organization.
Nowadays there exist decision support systems with advanced features. These decision support systems are called Online Analytical Processing (OLAP) systems. The usage of OLAP systems are in the field of data-mining. (Data mining is a study of finding out patterns across a large volume of data so that any business sensitive information can be obtained).
So the above characteristics confirm that decision support systems would help the organization in a greater extent for its growth. But decision support systems need well designed transaction processing system and management information systems because input would be taken from those systems directly or indirectly.
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2.2.4 Executive Information Systems As the name indicates Executive Information Systems are primarily for top level management. The executive information systems are used to make strategic decisions. Every department of the organization may provide data in their own version. But what the top level management wants is the crisp, easy to access data which can be directly used to make strategic decisions. The below given list characterizes the Executive Information Systems;
EIS doesn't require much training to use them.
EIS would normally receive input from both inside and outside of the organization.
EIS would provide options for viewing the same data from different dimensions which the top level management prefers to have.
Access to EIS would be restricted in organizations because they provide business sensitive information which would cause serious damage to the organization when leaked out.
Executive Information System is a handy tool for the top level management because it makes the top level management to get deeper insight in to the current status and the predicted future trends. 2.2.5 Office Automation System The systems that are explained above are for the managements. The major portion of the organization is workers or non-managers. Information technology has to assist these workers so that the productivity increases. It is the workers who carry out the regular activities of the organization. If the benefits of information technology don‟t reach these workers then it would be certainly a major factor which would affect the organization's growth.
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Office automation systems are a kind of information systems which would be used by every employee of the organization. Office automation systems provide a rich set of tools for increasing the productivity of the organization. Below given list is a set of characteristics of office automation systems:
The office automation systems are not restricted among employees. It can be used by anyone in the organization.
Office automation systems provide various technologies to reduce the human time required to carry out the operations.
Office automation systems would improve the accuracy of work carried out because they are well tested before their implementation.
Office automation systems are used to make better cooperation among various teams of the organization so that redundancy of work can be reduced. (Otherwise without their knowledge there is a possibility that same work would have been carried out in a redundant manner). Office automation systems involve various components in general. These
components are as listed below:
There exists a need for creation of various types of documents in an organization. For example sending letters etc. The Word processing system which is a component of office automation system can certainly reduce the redundancy of work carried out. For example if same letter (with simple data modifications like name, id etc) has to be sent to hundreds of customers then word processing systems would help to do this very effectively. Otherwise this work would require comparatively longer human time which affects the productivity.
Apart from word processing systems office automation systems provides tools like spreadsheets which are used to perform financial calculations.
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The presentation tools are other important components of office automation systems.
Simple image processing tools are also part of office automation systems. They can be used to perform the simple image processing tasks associated with documents creation.
These office automation systems can be used for scheduling of tasks also.
In addition to the above, there are facilities like videoconferencing which would be very useful in communication. If the organization is located at various places then these videoconferencing facilities are very much useful to save time. So these office automation tools would definitely improve the
productivity of the organization by reducing the time taken to carry out repeated tasks as explained above.
2.3 Information Systems Development Cycle In the previous section various information systems were explained in detail. This section would provide the steps involved in the development of information systems. Of course these steps are not only for information systems development but for any kind of software. The system development process is called “System Development Life Cycle (SDLC)”. The system development life cycle involves various steps as listed below:
Planning
Analysis
Designing
Development
Implementation
Maintenance
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As stated earlier this process is a cycle. So these steps would be repeatedly performed to make the systems powerful as well as bug free. The user requirements also changes as the time progress. So these changes need to be incorporated in to the system. Because of these factors development life cycle becomes a continuous process. Let us discuss in detail about each and every stage of the system development life cycle. 2.3.1 Planning Planning is a crucial phase not only in software development life cycle but in any activity that we carry out. When the target system is large in nature then planning becomes more crucial. There are various internal stages in planning. The very first task in the planning stage is to find out the objectives of the systems that you are going to develop. These objectives have to be defined in a well formatted manner so that there would not be any expectation mismatch at the end of system development. At this stage itself the scope of the system would be defined clearly. These objectives would be arrived at after having various levels of discussions with the user. Once the objectives are stated out clearly, the next step is to look for possible set of solutions for that problem. This becomes very important because at this stage you are free to look for various solutions in terms of their advantages and disadvantages. This would prove very useful at later stages. Among the various alternate solutions looked at, the cost and benefits of those solutions has to be calculated. This step would prove useful for management because they can find a trade-off between the cost of the project and the benefits.
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After all the above mentioned steps are carried out a report has to be prepared. This report would include various factors that you have identified so far. This report has to be submitted to the top level management. The top-level management would decide upon the further actions to be carried out based on the report that you have prepared. 2.3.2 Analysis After going through the report that you have submitted in planning phase the management would provide you the directions in which you have to progress. At the worst case the management can even decide to the wrap up the development process by looking at the cost benefit analysis. A thorough study of the existing system has to be carried out in the analysis phase. This is crucial because it is only to rectify the problems in the existing system a new system is developed. In order to rectify problem, first you have to understand clearly what the problems are. Then only you can think of solving those problems. The analysis stage would also indicate about the nature of changes that would be introduced in to the organization by the implementation of the proposed system. Analysis phase involves various steps. These activities are as listed below:
By using various techniques like interviews, questionnaires and observation, you have to gather data from the user. The quantity and quality of the data that you gather would play an important role in the success of the system.
After gathering the data it has to be analyzed. During this analysis process various modeling tools can be used. For example data flow diagram (DFD) is one such modeling tool which is widely used in system development life cycle. Apart from those modeling tools
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there are various other techniques that can be used. One such technique is called CASE (Computer Aided Software Engineering). Using these tools you can analyze various parameters of the system so that they can be tweaked for better performance.
A report has to be prepared at the end of analysis. This report would include various components like
Explanation about the existing system
Problems in the existing system
The proposed system description
The future course of actions
Analysis phase is where you exactly find out what is the flaw in the existing system. So the most important point that has to be remembered here is that the proposed system should not have these flaws again. The proposed system should ensure better performance than the existing system. There is one more point worth noting here which is called “Paralysis by analysis”. Though analysis is important you should not stuck-up with too much of analysis. The boundary and scope of analysis has to be clearly defined. 2.3.3 Designing It is only in the designing stage the proposed system's creation starts. The designing phase itself can be divided in to two more sub-phases. They are called
Preliminary design
Detailed Design
2.3.3.1 Preliminary Design Preliminary design would outline the capabilities of the proposed system. It is only in the preliminary design stage when the overall sketch of the proposed system is developed.
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In preliminary design another important component is the development of prototype system. Prototype is the miniature working model of the system. In prototype whole system is not miniaturized but few components are miniaturized. The reasons for developing prototype are to get an insight into the new system that is under development. Developing prototype should not take much longer time because prototype is not the final product the organization is going to use. Rather the purpose of prototype is to give the user a feel about the proposed system by providing certain graphical user interface components etc. 2.3.3.2 Detailed Design Detailed design would elaborate the concepts that have been discussed in the preliminary design stage. Here the capabilities of the proposed system would be described in detail. The detailed design specification includes various components. These components are as listed below:
Input requirement specifications
Output requirement specifications
Processing requirement specifications
Storage requirement specifications
Backup specifications
The components in the above list would be explained clearly in the detailed design specification. For example the input and output specification would throw light on how the proposed system handles the input and output. Similarly the storage specification explains the storage details about the proposed system.
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After all these tasks have been carried out a report has to be prepared. This report would include all the above mentioned specifications. It is the design phase where the proposed system's behaviors are clearly explained. 2.3.4 Development After the designing stage the next step is development. In the development stage the actual system development takes place. Appropriate techniques should be used during system development so that the delays can be avoided to a maximum level. The development stage has to clearly adopt the specifications given by the planning phase. Any unnecessary deviations from the specifications would give rise to conflicts. So these deviations have to be avoided. Since the development includes a team of programmers, proper arrangements like code version management, coding standards etc have to be made. This would result in better and faster system development. An unplanned development stage would make the implementation and maintenance phase hectic. So it is the development phase where the actual system is built. During this development it is not necessary that all components have to be developed from scratch. Where-ever feasible, the necessary third party components can also be used. The choice of selection of third party component can be based on various factors as listed below:
Cost advantages of the component: Since the development of a component in-house would require cost, the comparisons have to be made between the cost of developing the component from the scratch and getting the component from third parties.
Compatibility of the component: The component that you acquire from third party should be compatible with your code. If that component is
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totally different from your user interface specifications then it would not be encouraged to go for such components.
Quality: The component that you acquire from third party has to be well tested one. Otherwise it can cause some serious problems during the maintenance phase. In addition to software, the hardware that is needed for the system has to
be acquired at this stage. An improper hardware configuration would drastically reduce the performance of your system. So care has to be taken while selecting the proper hardware. Apart from the above activities there is one more activity called “testing” which decides whether the final system is going to be a success or failure. Because if the system is delivered to the user without proper testing then it can create wrong impressions about the new system at the earlier stages. Once the users got such an impression it would be very hard to make the system popular among the users. There exist various different types of testing methodologies. The complete description about testing is out of scope of this text. But here the important things about testing would be highlighted. Associated with any system there are two types of testing. They are as listed below:
Unit Testing: In the case of unit testing individual modules of the system would be tested for proper functioning. Unit testing objective is to rectify as many bugs as possible with respect to that individual module.
Integrated testing or System testing: Though all the modules are tested for their functionalities individually they have to be tested as a whole. This becomes necessary because when various modules interact with each other there is a possibility of errors out of this.
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These errors would be rectified in the system testing stage. The system testing objective is to remove all possible bugs in the system. Apart from the above mentioned testing methodologies there exist various other techniques also. Some of them are listed below:
White Box Testing
Black Box Testing
User Acceptance testing
Load testing etc
In the case of load testing the system would be tested for the amount of load it is capable of handling. In load testing large amount of data would be supplied and the behavior of the system would be tracked in response to this load. The system has to cross a particular load level. If the system breaks within such a load level then there is some flaw in the system development. Those flaws have to be identified and they have to be rectified. Once the system is well tested and certified for no major bugs it becomes ready for the actual implementation process. 2.3.5 Implementation After the testing process the system has to be implemented for the actual use. Since the system that is going to be implemented is relatively newer, the users of this system have to be trained. Proper level of training has to be given to the users who are going to use this newly developed system. If the training is not proper even the best systems can get negative reactions from the users. So it becomes the responsibility of the training team to make the users feel comfortable with the system. There exist different types of implementation. Few of the popular implementation types are as listed below:
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Parallel Implementation: In the case of parallel implementation both the old and new systems would be used for certain period of time. Once the new systems become reliable the old system would be discontinued. This methodology is called “parallel run”. When both the systems are in execution the following approaches can be followed with respect to data entry:
You can ask the users to enter data in both new and old systems manually. This would raise objections because it increases the work load drastically.
Another approach is to create programs that would automatically migrate the data that is been entered in to the new system in to old system. This would be welcomed by the users because there is no additional workload for them. But from the development team‟s point of view, they have to develop these migration tools which would require additional development time.
Phased Implementation: The new system would become usable in stages. Initially one module would be made available to the user. After some time, when it becomes stable the next module would be given to the users. This methodology would require a longer period of time for implementation.
Pilot Implementation: In pilot implementation the complete system would be released but it would be used only by a portion of employees. One of the problems with this approach is that when the system is released for entire set of users, they may give different opinions than the group of employees who used the pilot implementation.
Direct Implementation: It is the easiest implementation method. At the same time the riskiest method also. In this method from a
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particular day onwards the organization stops using the old system and it totally shifts to the new system. If the new system behaves as planned then there will not be any problem. But if the new system fails then the entire functioning of the organization would become risky. So the proper implementation method has to be identified after detailed discussion with both top level management and various levels of users who are going to use the system. 2.3.6 Maintenance Not only the information systems but any product requires maintenance. Maintenance involves two important components. They are as listed below:
Making sure that the implemented system is functioning smoothly.
When there is an additional or modified need for the user these changes are also incorporated into the system.
The first component would involve activities like backup etc. If the system requires networking then the network should also be maintained for proper functioning. The second component involves additions or modifications in to the actual code. When incorporating any new requirement or modifying an existing option, it has to be made sure that it will not affect other components of the system. At one point in time the cost of maintaining the system would go beyond a particular level. At that time again the System Development Life cycle has to start. Other reasons for starting it again may be like shifting to latest technologies etc. An information system which has been developed by properly following the instructions given above would be beneficial for the organization.
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Summary
Information systems are used to handle the information associated with an organization.
There exist various types of information like operational, tactical and strategic information.
There are various types of information systems like transaction processing system, management information system, decision support systems, executive information system and office automation systems.
Transaction processing system takes care of the operational information. It is mainly related to day-to-day business transactions.
Management information systems are for middle level management. They are used to generate summary information by taking the input from transaction processing systems.
Decision support systems are also used by middle level management. The decision support systems provide analysis of information received from various departments.
Executive information systems are for top level management. They would provide high level view of data associated with the organization.
Office automation systems would be used by everyone in the organization. They include components like word processing, videoconferencing etc.
SDLC stands for system development life cycle. It denotes various stages of system development.
Planning is the first stage of SDLC where the initial investigation would be performed.
Analysis is the phase where the existing system analysis is done by gathering data through various sources.
Designing phase involves both preliminary design and detailed design
Development phase is where the actual system development happens
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Implementation phase can be done in various ways like direct implementation, parallel implementation etc.
During maintenance phase smoother working of the system would be guaranteed and new requirements from the user would be incorporated into the system.
Self Assessment Questions Part I (Multiple Choice Questions)
IS stands for
Information Submission
Information Selection
Information Systems
All of the above
None of the above
Operational information characteristics are/is
Large volume in nature
Relates to day-to-day transactions
Doesn't require complex processing
All of the above
None of the above
CASE is
Computer Aided Software Engineering
Computer Aided System Estimation
Computer Applied Solution Evaluation
All of the above
None of the above
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Information system that helps the top-level management is/are
Management Information System
Executive Information System
Decision Support Systems
All of the above
None of the above
Which of the following is/are testing method(s)
White Box Testing
Black Box Testing
User Acceptance Testing
All of the above
None of the above Part II (Short Questions)
Write short notes on operational information?
List out various types of information systems.
How does Decision support system differ from Management Information Systems?
What are all various methods of implementation?
List out various phases of SDLC.
What are all the two sub-phases of designing?
What is the importance of training?
List out the activities in maintenance. Part III
Explain in detail about various types of Information Systems.
Elaborate on System Development Life Cycle.
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Answer Key Part I 1. c
2. d
3. a
4. b
5. d Part II
Operational information relates to the day-to-day transactions of the organization. Operational information is huge volume in nature. They don‟t require any complex processing.
Various types of information systems are as listed below:
Transaction Processing Systems
Management Information Systems
Decision Support Systems
Executive Information Systems
Office Automation Systems.
The major difference between management information system and decision support system is as follows: management information system provide summary of information but the decision support system provide analysis of the information which requires complex processing,
Various methods of implementation are listed below;
Parallel Implementation
Phased Implementation
Direct implementation
Pilot Implementation
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Various phases of SDLC are
Planning
Analysis
Designing
Development
Implementation
Maintenance
There exist two sub phases in designing. They are preliminary design and detailed design.
Training becomes an important process because without proper training the users of the system would feel uncomfortable with the newly developed system. So it is the responsibility of the training team to make the users feel comfortable with the newly developed system.
There exist two major activities in maintenance. One is to keep the system working smoother. Another is to incorporate any new changes given by the user. While incorporating changes the integrity of the system should be given importance.
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Lesson 3: The Hardware Introduction
Nowadays there exists an array of hardware devices that are either integral part of the computer or they can be attached as peripheral devices.
It becomes very much essential to have better understanding of hardware to feel comfortable with computers.
Different specialized devices exist to perform various tasks. As a student of information technology, you should enrich your knowledge base regarding these devices.
Objectives
Introducing various types of hardware architecture of computers (personal computers, workstations, supercomputers etc).
Explaining the working principle, advantages of various input devices like keyboard, mouse etc.
Providing detailed information about various types of display devices like CRT, flat panel devices.
Explaining the concepts about various types of printers like impact printers, non-impact printers etc. The types of plotters would also be explained.
Discussing the details about various storage devices like hard disk, compact disk etc.
3.1 Different architectures of Computers Computer hardware has undergone drastic changes over a period of time. This section would provide descriptions about various types of computers based on their architecture and purpose.
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3.1.1 Getting familiar with terminology It becomes necessary to have fundamental understanding of terminology used with computer architectures to get a clear picture about different kinds of architecture. Here you can get an insight into various terminologies specific to computer architecture.
Vacuum tubes: These were the units that constituted the first generation of computers. Vacuum tubes are nothing electronic tubes with a glowing filament in them. A good example for computer that used these vacuum tubes is ENIAC. The primary problem with vacuum tubes is their failure rate. Another problem is their big size.
Transistors: Transistor is one of the ground breaking inventions in the field of electronics. A transistor is basically an electronically operable switch. These transistors have got the capability to switch on and off huge number of times in a second. Transistors are very less in size comparing the vacuum tubes. The biggest advantage is that they consumed very less power for their operation. The reliability of transistors is comparatively more than that of vacuum tubes. Transistors played key role in reducing the size of computer.
Integrated circuits: Next to transistor is integrated circuit or simply called an IC. An IC can be considered as circuit in a chip. The development of ICs reduced the size of computer further down. Recent developments in IC include LSI (Large Scale Integrated Circuits) and VLSI (Very Large Scale Integrated Circuits).
All the elements of the above lists reduced the size and increased the power of computers to a greater extent. There is a famous law in computer science related to this which is called “Moore‟s Law”. It states that “The density of transistors on chip would double once every eighteen months”
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The Moore‟s law was developed by Gordon Moore in the year 1965. Moore‟s law is true till date. This is to say that the size of transistors is reducing according to above specified Moore‟s Law. There exist different types of computers. They are as listed below:
Personal Computers
Workstations
Mini Computers
Mainframe Computers
Super Computers
3.1.2 Personal Computers A personal computer is simply called “PC”. The computer that most of you use for your daily use is called personal computer. Personal computers have following characteristics:
Personal computers are relatively inexpensive.
Personal computer can accommodate maximum of one user at a time.
Personal computer generally has one microprocessor (Recently there is a variation to this feature. Nowadays personal computers can hold more than more microprocessor)
Personal computers are generally used for word processing, DTP, spreadsheets, games and surfing internet.
Personal computers were introduced during the year 1977 by Apple. This personal computer was called Apple II. This became very much popular during those days. During the early 1980s IBM launched their version of personal computer called IBM-PC. Later to this, the term PC was used to refer IBM-PC. IBM-PC changed the attitude of users towards computers. After the advent of IBM-PC computers were getting more popularity among the general public.
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In personal computers there are two types based on the assembling or arrangement of components. They are
Desktop Model: In desktop model PCs the monitor would sit on top of the CPU. This model would require only very small space because there is no need for additional space for CPU.
Tower Model: Tower model PCs are also called Mini Tower PC. In the case of tower type the components inside the cabinet would be stacked on top of each other i.e. Hard disk, Floppy disk drive, CD Drive and other components would be placed on top of one another. The advantage of tower model is that if you want to add any more components like additional storage etc it would be relatively easy comparing to Desktop model.
One more point worth noting here is that recently the gap between the highend PC and the workstation is blurred. In other words nowadays you can find PCs that has advanced computing facilities like more than one microprocessor, good amount of main memory etc. 3.1.3 Workstations Workstations are more powerful comparing to personal computers. Workstations have got powerful microprocessors. The display associated with workstation will also be powerful than that of personal computers. Since the power of workstations is more they are used for applications like CAD / CAM, complicated software development process etc. Workstations would generally have built in network support i.e. they can be easily connected to a network. (Sometimes any computer connected to a network is called workstation though they may be personal computers) Workstations are ideal choice for graphical applications like Digital Image Processing etc because this task requires higher computing power and increased amount of RAM.
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Workstations would have mass storage devices. There is an exception to this where mass storage will not be there. Such types of workstations are called diskless workstations. The operating systems that are used with workstations are generally UNIX, Linux or Windows NT (Windows New Technology). 3.1.4 Minicomputers Minicomputers are more powerful than workstation. Mini computers can support hundreds of users at a time. (This is the primary difference between a workstation and minicomputer. A workstation is a single user computer) Therefore to a minicomputer hundreds of terminals can be connected. These terminals can be operated simultaneously. Mini computers do have large sized storage and RAM because all the terminals connected to minicomputer would use the resources of minicomputer. So it has to possess good amount of resources to support smoother functioning. 3.1.5 Mainframe Computers You can think of mainframes as power enriched minicomputers. Mainframe computers can support thousands of users simultaneously (minicomputer can support hundreds of users at a time). In order to support thousands of users at a time mainframes have to possess huge amount resources like computing facility, storage and main memory. All the terminals connected to a mainframe can submit different types of tasks to the mainframe. Mainframe has to distribute its resource among all these tasks. So in the case of mainframe task management and memory management has to done much effectively. To perform this there exist specialized operating systems available for mainframe computers.
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Generally the terminals connected to mainframe are called “dumb terminals”. They have the capability of simply input and output. At the same time they submit all the processing to the mainframe. Mainframe computers are mostly used for bulk data processing tasks. For example in an organization like bank there would be lots of tasks which would be process intensive. These tasks can be assigned to mainframe to get output faster as well as with good accuracy. After the advent of Client-Server technology the popularity of mainframes got reduced. More on Client-Server technology would be discussed in later portions of this text. 3.1.6 Supercomputers Supercomputers are fastest computer systems. Supercomputers were introduced during 1960s. Generally supercomputers are a combination of many computers working together. The primary difference between supercomputers and mainframe is as follows: A mainframe computer distributes its processing capacity among solving many problems at the same time. At the same time supercomputers use all of their resources to solve a single problem as fast as possible. The applications of supercomputers are in domains like weather forecasting, nuclear energy research etc. In general any problem which would require processing time in terms of hours, days, month etc can be submitted to supercomputers to get the result as early as possible. Our country has got indigenously developed supercomputers called PARAM. It stands for PARallel Accessing Machines. Other popular examples includes IBM Blue Gene (Which is considered one among the fastest list) etc. The processing speed of Supercomputers are measured in units of FLOPS (Floating point operations per second). For supercomputers the processing speed would be in terms of Terra FLOPS.
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3.2 Real Time Systems Real Time Systems are simply called RTC. They operate under specific time a constraint i.e. there is a predefined limit with in which the system has to produce its output. There exist two types of real time systems. They are as listed below
Hard Real Time System: In hard real time system the fixed deadline is very important. Output delivered after this limit would be useless. There are plenty of examples for hard real time systems. A system that is controlling the airplane is an example for hard real time system. If such a system doesn‟t deliver the output with in the deadline it would have certain chaotic effects.
Soft Real Time System: In soft real time system if the deadline is missed then the output can still be usable but the quality would be affected. A system that is controlling a game can be considered as soft real time systems. At the same time the difference between the expected time and actual time should not become very high. In such a case the output would become lower in terms of quality and would become useless.
Real Time Systems are not same as high performance systems. It is not necessary that real time system should be produce output immediately but they have to produce the output within the fixed time limit.
3.3 Transaction Processing Systems Transaction processing system would be operating on the basis of Transactions. A transaction may consist of „n‟ number of tasks. These task has to be carried out in full or nothing manner.
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For example consider the following scenario: You have to transfer some amount from account A to B. You would encounter following steps:
Step 1: A_Balance = A_Balance – Amount
Step 2 : B_Balance = B_Balance + Amount
If the system fails after the first step then the amount would have been subtracted from A‟s account. At the same time B‟s balance would not have updated. In this scenario all the above mentioned steps has to be carried out in full or no step should be carried out. These transaction processing systems should follow the atomicity principle i.e. each transaction has to be considered as a single unit. It should not be divided further. If these systems don‟t follow atomicity principle then the integrity of the system would become a question mark.
3.4 Laptop Laptop computers are portable computers. They are now becoming equivalent to their personal computer counterparts in their processing speed and memory capacity. Being portable requires many features:
Laptops are less in weight. This makes porting from one place to another easier.
Power requirements of the laptops are very less. They operate on a battery (Though you can operate even by connecting it to main power supply). To achieve this less power requirement flat-panel displays are used.
Laptops are nowadays called notebook computers. Since they have become ultra slim and looks like a notebook (even you can carry it like a notebook) this name is used.
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Since the notebook computer uses advanced technologies to assemble all the components in much lesser space the cost of note book computers are higher. (If you consider a desktop PC and note book with similar processing capacities the cost of later would be much higher).
3.5 Palmtop Hand-held computers are called palmtop. The name palmtop is given because it can sit easily with in your palms. These palmtops are ultra portable than the notebook computers. The purpose of notebook computer and palmtop varies. Notebook computer can hold majority of the applications that is possible in desktop PCs. But in the case of palmtop application types would be limited. Palmtops are otherwise called PDA (Personal Digital Assistant). They are a combination of mobile phone + portable computers. These palmtop computers would have wireless networking features. They can be easily linked with a Wi-Fi network. PDA has got certain advanced features like voice recognition, hand writing recognition etc. If voice recognition feature is there in a PDA then you can control such a PDA through voice commands.
3.6 Client Server and multi-tier Architecture Client server architecture has totally revolutionized the computing paradigm. With the advent of client-server computing less powerful machines can be attached to a powerful machine and carry out the operations so that maximum throughput would be achieved. Client is the computer or software program which request for certain services. At the same time server is a computer or software program that reacts and responds to the client requests.
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There is a possibility that client and server can reside even on the same machine (if both of them are software programs). The power of client server computing can be understood by the fact that the internet works on the client server architecture. The web browser that you use in your machine is the client program. These client programs communicates with server i.e. web servers to get the required web page or web service. In order to communicate they follow certain standard protocols. There are basically two types of clients. They are thin client and rich client. In the case of thin client everything has to be carried out at the server side. The client machine would only receive input from the user and display the output back to the user. In the case of rich client some of the processing would be carried out in client side itself. If the client machine is having reasonably good hardware configuration then the resources at client can be harnessed. By this the load on the server would be reduced. One thing to remember is that to implement rich client architecture the client machine should have reasonably good hardware configuration. The general client server architecture can be as simple as two tire architecture i.e. client is one layer (tier) and server is another layer. In the case of n-tier architecture multiple layers are introduced in between. For example a separate database server can be introduced for taking care of database related operations. In general many applications are designed in three tier architecture. One tier for presentation, another for business logic and another would be for data or storage. The n-tier architecture makes the maintenance of the applications easier because the bugs (errors) can be easily identified and rectified. It also provides modularity i.e. if the performance at one layer is not good you can even think of totally replacing it with new one without making modifications in other layers.
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3.7 Input Devices A computer may not be able to perform its role if the input data is not supplied. The input devices are the peripheral devices that are connected to the computer to receive the input from the user and transmit it to the central processing unit. There are certain input devices which are used frequently and others which are used rarely. This section would elaborate on different types of input devices, their usage and functionality. In general input devices can be classified in to three broad categories on the basis which type of data they handle. This classification is as shown below in Figure 3.1 Figure 3.1: Input Device Categories
3.7.1 Character Input Devices Associated with any computer you would have seen a device called keyboard. Keyboard is a character input device. Through character input devices you can enter alphabets, numerals, special characters and few control characters like Alt, Ctrl, and Shift etc. Keyboards can be classified into two types. They are as listed below:
Mechanical Keyboard: In a mechanical keyboard each key has a mechanical setup which facilitates the communication between the keyboard and the underlying circuitry.
Membrane Keyboard: In membrane keyboard instead of the mechanical setup a membrane would be used. Normally these types of keyboards are cheaper than the mechanical keyboard. At the same time mechanical keyboards has got longer durability than the membrane keyboards.
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Associated with any keyboard there is a circuitry inside the keyboard. You have a key matrix which is used to convert the key presses in to actual key codes which the computer can understand. Keyboards are modeled on the basis of their predecessors i.e. the typewriters. The keyboard layout generally followed is called “QUERTY”. It represents the first six keys present on the top alphabet row. Apart from these general keyboards there are certain specially designed keyboards. Few of them are listed below:
Projection Keyboards: Projection keyboard is one of the recent innovations related to character input devices. In this type of keyboard the key layout would be projected on any flat surface. And the user can use it just like the normal keyboard. Based on the movement of fingers the key strokes would be recognized.
ATMs and POS terminals: These are specially designed for a particular purpose. The ATM key pads would have only the required keys that are necessary to perform your transactions. Same is the case with POS (Point Of Sale) Keyboards.
Another important thing that you would notice with respect to keyboards is the key count. The number of keys may vary depending on the model and manufacture of the keyboard. Generally you would find 104 or 108 keys in the desktop machines. In the case of laptops the number of key would be little bit lesser (85 approx). As said above the number of keys may vary based on various factors. In one word we can say that, keyboards are the most used peripheral device associated with a computer system.
3.7.2 Pointing Devices Another category of input devices are the pointing devices. After the advent of graphical user interface operating systems there was a need for
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pointing devices. Pointing devices are used to locate the cursor on a particular location on the screen and execute the command by clicking etc. There exists an array of pointing devices available today.
Mouse: Mouse is a generally used pointing device. It has the capability to recognize the movement both in terms of X and Y axis. Bill English invented the ball mouse in the year 1972. The number of buttons in a mouse may vary from one to three. But the normal one is two button mice. These buttons are used to perform right click and left click (called click). Apart from these buttons there can be a scrolling wheel in the mouse. In addition to click actions you can also perform an action called “drag” with the mouse. In drag action you would be moving the mouse by holding any one of the mouse buttons. In mouse itself you have two variations they are
Mechanical Mouse: This category of mouse would have a circular ball beneath them. When the user moves the mouse the ball rotates accordingly. Based on the rotations of ball, signals would be sent to the system so that proper actions can be taken. One of the major problems with mechanical mouse is that it can accumulate dust around the ball which would disturb the free flow of the mouse.
Optical Mouse: In the case of optical mouse the mechanical ball is replaced with light source. This light source and the sensors inside the mouse would recognize the movements of the mouse. The problem that we specified with mechanical mouse is not there in the case of optical mouse. But optical mouse do have a drawback that they may not be able to recognize movement in certain glassy surfaces. Comparatively optical mouse is more flexible than the mechanical mouse.
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Trackball: Trackball may be considered as the upside-down version of the mouse. Trackball consists of a ball located on top. This ball can be controlled by using the finger. The advantage of using trackball is that it provides higher precision. This higher precision would be very much helpful in applications like CAD.
Touchpad: You would find the touchpad in laptops. Touchpad would consist of an area in which you can slide your fingers to control the movement of cursor. The click action would be performed by tapping your finger on the touchpad area. There are buttons available in touchpad which you can use for the click and double click etc.
Joystick: Joysticks are specialized input devices which are mostly used with computer games. But apart from computer games it has its uses in other domains like wheel chair controlling etc. In larger cranes and trucks also joysticks are used to achieve finer control.
Touch screen: Touch screens acts as both output as well as input devices. Touch screens are sensitive to pressing. The advantage of touch screen is that you can directly touch on the displayed item for selection. This would be very much useful in places like kiosks, information rendering terminals and ATM etc. Touch screens are very much user friendly i.e. they are self-explanatory.
Digitizers: Digitizers are pen like devices which can be operated on a specialized board. This would be useful for artists because drawing with the help of mouse or other pointing devices is not easier. When the digitizers are used they provide the feel of directly operating with the normal pen. Digitizers are available both in wired as well as wireless forms. The wireless digitizers would be very much flexible for the users.
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3.7.3 Multimedia Input Devices Modern day computer supports various types of media like sound, image, video etc. So there is a need for input devices which has the capability to capture all these above mentioned media. This section would illustrate various multimedia based input devices.
Scanners: When you want to input an image into computer scanners would be very much helpful. The purpose of scanners is to transform the physical images (for that matter text or scribbling) into digital format. There exist various types of scanners. For example scanner having capability to support multicolor, single color etc. Important attribute of any scanner device is called the “dpi” (dots per inch). This dpi actually decides the quality of images. More the dpi higher the quality of image. At the same time large dpi images would be much bigger in size. They would also require longer time to scan the document. All the scanners allow the users to select the dpi they want. It would provide a list of resolutions (dpi) from which user can select one according to his/her need. Scanners are widely used in the desktop publishing industry (DTP).
Character Recognition Devices: There exist many types of character recognition devices. Most popularly used ones listed below:
Optical Character Recognition: Reads pre printed characters. But these characters are written using predefined styles
Magnetic Ink Character Recognition: Used to recognize characters written using magnetic inks. Normally used with bank checks.
Optical mark Recognition: Used to recognize pencil marks at predefined locations. Normally used for answering multiple choice type questions.
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Barcode Readers: These devices are used to convert the barcodes printed on a physical object to electronic form. Barcode readers extract data from the barcode.
Audio input devices: To input audio in to the system generally microphones are used. The associated software recognizes the signals from microphone and converts those signals to digital form. Once the audio has been received by the system it can be saved in plenty of formats like wav, mp3, ra etc. In combination with these audio input devices now you have specialized software called “voice recognition systems”. These voice recognition systems can transform voice in to text. The accuracy of recognition depends on the training and the quality of the software used to recognize.
Video input devices: To capture the video into the computer you can use the video input devices. Webcam (Web camera) is one of the popularly used to video input device. These cameras can be attached to the USB port of the computer. The quality of the video again depends on the resolution that your camera supports. Higher the resolution larger the video size. In addition to webcams the digital cameras can also be connected to the computer system to transfer the captured videos.
Apart from the above mentioned input devices there exist certain bio-metric devices. For example the finger print reader is one such example for bio-metric readers. Nowadays there are finger print readers are available in laptops itself for additional security. Iris pattern recognition systems are used to recognize particular person by scanning patterns inside the eyes. Recent developments into these kinds of recognition devices are RFID (Radio Frequency Identification). Small RFID tags can be attached to objects which can be recognized later. The RFID is getting highly popular in retail shops industry and Library domain.
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3.8 Secondary Storage The primary memory is volatile in nature i.e. when it get disconnected from the power supply the contents stored in it would be erased. So there is a need for storage which is non-volatile. Secondary storage would exactly perform the same. A comparison between primary and secondary storage would be interesting. Primary storage is faster comparing to secondary storage. At the same time the size of primary storage is very less. There exists variety of secondary storage devices. This section would provide detailed content regarding the usage and working principle of these secondary storage devices. The below given is the list of secondary storage devices that you would study in this section:
Floppy disk
Hard disk
Compact Disk
Magnetic Tapes
Flash memory
3.8.1 Floppy Disks Floppy disk is a portable secondary storage device. Normally floppy disks are called “diskette”. Floppy disks are available in various sizes:
8 Inches
5.25 Inches
3.5 Inches
In fact 8 and 5.25 inch disks are not in use today. Normally used ones are 3.25 inches disk.
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Data are stored into floppy disk by magnetic principles (in a circular plate which is located inside the floppy disk). To read the data from floppy disk you should have floppy disk drives. In line with the size of the floppy disk there are different kinds of floppy disk drives also exists. The floppy disk drives are normally located in the cabinet itself. There exist external floppy disk drives also. You can find these with very compact laptops where there is no space to place the floppy disk drives. In such case you can connect the floppy disk drive through USB port or similar. Floppy disks drives have the capacity to read and write the data into a floppy disk. At the same time a floppy disk can be made read-only by using the writeprotect notch. The write protection mechanism is not the same in 5.25 and 3.5 inches floppy disks. In 3.5 inch floppy write protection would be enabled if the write protection window is open. In the case of 5.25 inches when the opening for write protection is closed write protection would be enabled. Storage area of floppy disk is logically divided into tracks and sectors. Tracks are the concentric circular areas of the disk. Each track is divided into many sectors. Sectors are wedge-shaped. These sectors are invisible in nature. Inside the floppy disk drive there is a mechanism called “head”. The head is responsible for reading and writing data to and from the disk. The circular plate inside the floppy disk which holds the data would rotate and the head would also make movements so that the specified track and sector can be located. The size of the 3.5 inches floppy disk is 1.44 MB. Before using any floppy disk it has to be formatted. Generally formatting is a process which is applicable to all the secondary storage devices so that these devices would become usable. Apart from the traditional floppy disks there are certain specialized floppy disk called Zip disks and super disk etc. Zip disk would be in capacity of 100 or 250 Mega Bytes (Iomega Zip disks). The super disks are of size 120 Mega Bytes. This is called LS-120 diskette.
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Though the floppy disk has the advantage of portability they have few disadvantages. They are as follows: The data stored in the floppy disk are sensitive to magnetic materials. So there is a possibility that the data would get corrupted easily if it comes in contact with magnetic substances. After the advent of other storage devices like CD and Thumb drives the usage of floppy disks are getting reduced. The reason is the increased storage space in the later devices. Roughly if you compare the amount of storage in Floppy (1.44 MB) and a typical compact disk (700 MB) then you can realize how much the later devices are huge in capacity. This is the primary reason for diminishing popularity of floppy disk these days.
3.8.2 Hard disks Hard disk is a fixed secondary storage device. Floppy disk are easily removable and hard disk are not so. Hard disks are some time called Winchester disks. Hard disks are much larger in size. As of today a typical hard disk is around 80 to 160 GB. But you can find hard disk with much higher storage space also. In the case of floppy disk there is a separate device called floppy disk drive but with hard disk the disk and drive are tightly packaged. Whatever you see externally as hard disk is in fact a combination of both hard disk and hard disk drive or simply called HDD. In combination with hard disk there is unit called hard disk controllers. The role of hard disk controller is acting as a interface between the hard disk and the computer. The hard disk controllers are off various types. Popularly used ones are as listed below:
SCSI
- Small Computer System Interface
IDE
- Integrated Drive Electronics
EIDE
- Enhanced Drive Electronics
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With the help of SCSI up to 8 HDD can be controlled where as in the case of ATA the maximum is 4. So the selection of SCSI or ATA depends on the usage of the hard disk. A typical hard disk is packaged with many platters inside. These platters are made up of glass ceramic or aluminum disks. These platters are coated with magnetic materials. As specified for floppy disks, hard disks too have tracks and sectors. Hard disk additionally has a unit called cylinder. Data would be stored on these platters as magnetized spots. In hard disk there would be read/write head. This read/write head doesn‟t make physical contact with the platters. There would be micro gap between the actual head and the platters. If the head touches the platters then it could cause some damage to the data on the hard disk. Even micro sized dust can cause this damage. In order to avoid this, hard disks are packaged in an air tight manner. So it advised not to open the external box or cover of hard disk because it can cause the above mentioned damage. Another factor to consider with hard disk is “rpm”. It stands for revolutions per minute. Higher the revolution of the hard disk more the speed of data retrieval. A typical hard disk today has an rpm of 7200 i.e. the platters rotates 7200 times per minute. As you have already understood the fact that capacity of the hard disks are very huge, they are partitioned into many logical drives. This is for the following purpose:
Better Organization: Each partition can be allocated for a specified task so that the data can be organized in a better manner.
Increased Speed: The size of the logical drives would be comparatively lesser than the actual size of the hard disk so it becomes very easy to locate data in these partitions. By this the speed of data retrieval actually increases.
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Though it has been mentioned that hard disks are fixed storage devices, there exist removable hard disks also. These devices are called External hard disks; these external hard disks are connected to the computer through USB ports. Another category of hard disk exist which are called RAID (Redundant Array Independent Disks). RAID is sometimes called Redundant Array of Inexpensive Disks. In RAID there exist multiple hard disks connected together. This combination may provide many benefits like security of data, improved performance in terms of speed. There exist many levels of RAID exists called RAID 0, RAID 1 etc.
3.8.3 Compact Disks Both floppy and hard disk store data based on the magnetic principle. There exists another class of storage devices which store and retrieve data with optical principle i.e. with the help of light, to be specific laser light. So the compact disks are called optical disks. The diameter of a standard compact disk is 4.75 inches. Of course nowadays miniature versions are also available. Similar to floppy disk drive there exist Compact Disk Drives for reading data from Compact Disk. Compact disks are generally mentioned as CD or CD ROM. The working principle of CD ROM is as listed below:
Write Operation: To write data in to CD ROM high power laser beams are used. These laser beams create small pits on the surface area of the disk. .
Read operation: To read data from CD ROM low intensity laser beams are used. Based on whether it is a pit or normal surface it would be recognized as 1 and 0.
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The speed of CD ROM drives are mentioned in multiples of “X”. The value of “X” stands for 150 kilobytes per second. So if the speed is mentioned as 40 X then it stands for 40 x 150 (= 6000) kilobytes per second. There exist many variations of CD as listed below:
CD-R: These CDs follow the Write Once Read Many time principle. CD-R stands for Compact Disk Recordable.
CD-RW: The data recorded on this CD-RW can be erased, rewritten. CD-RW stands for Compact Disk Rewritable.
There is another type of optical disk which is called DVD. DVD stands for Digital Versatile Disks. The size of a DVD is in terms of GB. Normally it ranges from 4.7 GB (Giga Bytes) to 17 GB. So DVDs have much larger storage space then CD-ROM. The reason for increased size of DVD is that, here the pits created are off much smaller size than the CD. In addition to this, there exist more layers on which pits can be created. This also provides increased space for data storage. Another important fact is that the wavelength of laser used in DVD is lesser than that of laser used with CD. To read DVD you have to use DVD drives. Now there exist drives which can read both DVD and CD. These drives are called combo drives. Generally combo drives can perform read operation on DVD and Read/Write operation on CD.
3.8.4 Magnetic Tapes Magnetic tapes are not generally used with personal computers now. They are almost outdated. Only purposes for which magnetic tapes are used today are for backup. Magnetic tape consists of plastic tapes rolled in a circular form. Plastic tapes are very thin in nature. These plastic tapes are coated with magnetic materials. In these magnetic coating only the data is written or read back.
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Access speed of these magnetic tapes is very slow. So they can be used in places where the speed of data retrieval is not a primary concern. As specified earlier primary purpose of these tape drives are archival. The magnetic tapes resemble the audio cassette. These are called tape cartridges. Normally used types of tape drives are DAT. DAT stands for Digital Audio tapes.
3.8.5 Flash Memory The floppy disk and hard disk comes under the classification magnetic memory. The CD and DVD come under the category called optical memory. Both these types of includes mechanical components which may lead to easier damage. There is another classification of memory which is called semi conductor memory. The RAM (Random Access Memory) that you use for primary memory for the computer is also semi-conductor memory. But RAM is volatile in nature. Flash memory is semiconductor memory as well as non-volatile. Flash memory belongs to EEPROM. It stands for Electronically Erasable Programmable Read Only Memory. So EEPROM supports all the following operations: Read, Write and Erase. Nowadays flash memories are getting more popular among the users because of its ease of use and portability. Also the cost of flash memory has become very cheaper. Flash memories are used not only with computer but with various other electronic devices like digital cameras, mobile phones etc. The smaller size of flash memory makes it convenient to use it into all of the above mentioned devices.
3.9. Output Devices Can you think of a computer that doesn‟t has any output device? In the case of personal computers the answer is absolutely “No”. This question
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emphasizes the importance of output devices. Like the input devices which have direct communication with the user, output devices also has close contact with the user. The computers don‟t know anything more than 0 and 1. Imagine the output as simply a sequence of 0s and 1s. This would make the computers almost unusable. The output devices provide a solution this problem. These devices provide the output in the human readable form. Generally the output devices can be broadly categorized into two types. They are depicted in the following figure 3.2. Figure 3.2 Output Device Categories
Softcopy Output: Softcopy output devices do not create any permanent record of the output. For example an output device like monitor is an example for softcopy output.
Hardcopy output: Hardcopy output devices create permanent record of the output. For example an output device like printer is an example for hardcopy output device.
This section would elaborate on both of the above mentioned types output devices. Their usage, functionality is described in this section. Before explaining the output devices in detail it would be better to understand few fundamental concepts of output. Any output device has got an attribute called “resolution”. Resolution refers to the quality of the output. Resolution of the output device is generally specified like 800 x 600, 1024 x 768 etc. This indicates the number of pixels across both X and Y axes. The multiplication of these two values would give the total number of pixels in that output device.
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You would come across one more term related to output devices which is called “pixel”. Pixels are relevant to softcopy output devices. Pixel is the smallest individual addressing element of an output device. In the case of hardcopy output devices the same is measured in terms of “dpi”. It refers to dots per inch.
3.9.1 Softcopy Output devices As stated earlier softcopy output devices don‟t create any permanent trace of the output. In other words you can say these outputs are intangible in nature. There exist two broad types of softcopy output devices. They are as listed below:
CRT displays
Flat panel displays
3.9.1.1 CRT displays CRT stands for Cathode Ray Tube. These CRTs are popularly used from the days of televisions. There is one important difference between the CRT used in TVs and CRT used in computers. The resolution of CRT used in computers is much higher than the counterparts in Televisions. CRT is available in both monochrome as well as multicolor versions. CRT is basically a vacuum tube. In side the CRT there is a unit called electron gun. It emits electrons. These electrons are then deflected by the yoke. Finally when the beam hits the screen which is coated with phosphor it illuminates. Number of pixels may be turned on or off by this process. This pixel illumination actually creates the output on the screen. The CRT devices are also called raster display devices. Here the electron gun creates the images as lines drawn from left edge of the screen to right edge of the screen.
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In the case of multicolor display each pixel is made up of three dots. These dots are of colors red, green and blue. Any color that you see in the monitor is created with the combination of these three colors. The primary advantage of CRT display is that they are cheaper in cost. The demerits of CRT displays are as listed below:
CRT displays are not easily portable. They are very heavy in nature. They occupy much larger space.
CRT displays are not power conscious i.e. they consume much higher power.
3.9.1.2 Flat-panel Displays Flat panel displays are getting highly popular these days. These flat panel displays consume very less power comparing with CRT displays. They occupy only very less space hence they become portable. One of the major constraints in portable computers like laptops is the power consumption. Hence these flat panel displays consumes very little power they become ideal choice for portable computers like laptops etc. There exist many types of flat-panel display devices. They are listed below:
Liquid Crystal Display: The types of display devices are most popular in nature. Here liquid crystals are used in between LCD panels. In LCD devices there would be grid on which you can apply voltage to activate particular intersection positions. In LCD device there are again two categories. They are :
Active matrix LCD: This active matrix LCD uses TFT. TFT stands for Thin Film Transistor. TFT displays can be viewed from any angle.
Passive matrix LCD: Passive matrix LCD includes twisted nematic LCD (TN-LCD) and super twisted nematic LCD (STN-
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LCD). These display in these devices can be viewed perfectly only from the perpendicular angle. This is one problem with passive matrix technology which is solved in active matrix technology.
Plasma displays: Instead of liquid crystals in plasma panels light emitting gases are used. These gases would be used to generate ultra violet rays. These ultra violet rays would stimulate green, red, blue phosphors.
3.9.2 Characteristics of Display Devices Display device has got certain characteristics on which you can decide the quality of the display device. This section lists out various characteristics of display devices:
Refresh Rate: The number of times the display is redrawn per second indicates the refresh rate of the device. If the refresh rate is very less then you would find the display flicker. The refresh rate of a display device is measured in terms of a unit called Hertz. Most of the display devices provide the choice to adjust the refresh rate to the user.
Dot pitch: Dot pitch refers to the space between pixels. If the space is much lesser then the display would look good. The dot pitch is generally referred as “dp”.
The quality of the display doesn‟t only depend on the actual display device but it also depends on another important unit called “display adapters”. There exist various types of display adapters. This display adapter acts as the interface between the system and the display device. This is shown in the Figure 3.3. So these display adapters provides input to the display devices. There exist many types of display adapters like SVGA, XGA etc. The resolution of the display device is also dependent on the kind of adapter that is used.
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Figure 3.3: Display Card as Interface between CPU and Display device
3.9.3 Hardcopy output Hardcopy output devices create a permanent record for the output. The softcopy output alone may not be sufficient for many purposes. So there is a need for a device which transfers the output generated by the computer into a physical medium like paper, film etc. Printers provide solution to the above mentioned problem. There are many types of printers exist. On the basis of characters they print at a time, printers can be classified into two types. They are character printer and line printer. Character printer prints one character at time where is in line printers all the characters in a line would be printed at a time. On the basis of the type of contact with the paper printers can be classified into two types. They are as given in Figure 3.4:
Figure 3.4: Classification of printers 3.9.3.1 Impact printers As the name indicates impact printers makes physical contact with the paper to print. Popularly used impact printer is the dot-matrix printer. In dotmatrix printer there would a print head which consists of small pins. These pins will be projected forward to formulate characters (even images). Then these pins will punch on the carbon ribbon located in front of them. These impressions would be transferred to the paper beneath the ribbons. The number of pins on the print head decides the quality of the printed output. Higher the pin count greater is the quality. The primary advantages of dot-matrix printer are as listed below:
They are cost-effective in nature. This is achieved by the reduction of recurring cost for printing.
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Many other printers can print only on good quality paper where as dotmatrix printers may even print on low quality papers.
Dot-matrix printers can print on more than one paper at the same time by using carbons. The demerits of dot-matrix printers are as listed below:
The speed of the printer is slower when compared to other printers.
The resolution of the printed output also is not best.
3.9.3.2 Non-Impact Printers As the name indicates non-impact printers do not make physical contact with paper for printing. There are many popularly used non-impact printers. They are:
Ink-Jet Printer
Laser Pinter
Thermal Printer
3.9.3.2.1 Ink-Jet Printer Ink-Jet printer prints by spraying droplets of ink on to the paper. These droplets are electrically charged. The ink-jet printer has got many nozzles. These nozzles are the micro level openings. Through these openings only ink would be sprayed on the paper. In the case of color ink-jet printers there would be individual tanks for primary colors. By combining these primary colors the image would be formed on the screen. There are plenty of advantages for ink-jet printer. They are as listed below:
The quality of output generated by ink-jet printers is very high.
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Ink-jet printers don‟t produce any noise during printing (In the case of dot-matrix printers noise would be generated during printing)
On the other hand ink-jet printers do have certain drawbacks. They are as listed below: 2. Recurring cost of ink-jet printers are higher. (i.e. cost per page for printing would be higher) 3. Hence the ink-jet printer consists of micro sized nozzles they are very sensitive to dust. The dust on these nozzles can easily make the output quality to very low.
3.9.3.2.2 Laser Printers Another type of non-impact printers is laser printers. Laser printers are getting more popular nowadays because of continuous reduction in cost of laser printers. The working procedure of laser printer can be outlined as follows: Laser printers create an electrical image of the document to be printed on a drum i.e. dots on the drums would be charged with the respective image of the document to be printed. These charged portions of the drum attract the specialized particles called “toners”. Then by applying heat toner would be made permanent on the paper. There are plenty of advantages for Laser printer. They are as listed below:
Laser printer can produce both good quality image and text output.
Laser printers print much faster. (A typical laser printer can print 8-10 pages per minute)
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The output can be printed on materials other than paper like polymer sheets. This polymer sheet printing is widely in the Desktop Publishing industry.
Laser printers have become optimal choice for home and office uses. There exists an array of laser printers available in the market today. Based on the requirements a proper model can be easily selected. In the case of color laser printers the cost of printing is still higher. One of the problems that you would encounter with laser printer is that, by some how if a scratch is formed on the cylinder then it would have impact on all the consequent pages to be printed. Among the types of printers that exist today you can easily say that the laser printers are certainly better than other types of printers. 3.9.3.2.3 Thermal Printers Thermal printers are one of the rarely used types of printers. In thermal printers waxes are used to print. Head would be applied on these waxes to create the actual output. Thermal printers are costlier in nature. You can select thermal printer if you want to have highest quality of output. Apart from these printers there are certain special category printers as listed below: 11. Multifunction printers: These devices perform more tasks than printing like fax, scan, photocopying etc. 12. Label printers: These printers are designed to print only the labels. They are inexpensive in nature.
3.9.3.3 Plotters Plotters are specialized hardcopy output devices. Plotters are generally used to plot architectural drawings or engineering designs. The dimensions of
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output generated on plotters in terms of feet. Generally plotters are used in those circumstances when the size of the output is very large so that they can not be printed on normal printers effectively. There are many types of plotters. The following list illustrates various types of plotters: 19. Pen plotter: The pen plotters create output by using many colored pens. The number of colors may go up to eight. These pens can draw on the paper or any other suitable medium. The output here is formed by combination of lines not by the combination of dots as in other printing devices. 20. Electrostatic plotter: Electrostatic plotters work similar to photocopiers. In electrostatic plotters toners are used (similar to laser printers). These electrostatic plotters are costlier and require regular maintenance to ensure proper functioning. 21. Ink-jet plotters: Ink-jet plotters are comparatively cheaper. They consume large quantities of ink. You have to wait until this ink dries. Otherwise there is a possibility of smear. 22. Thermal Plotters: Thermal plotters require special paper. They can print only with two colors. At the same time thermal plotters are faster. Summary 1. There exist various types of hardware architecture like personal computers, workstations, mainframe, supercomputers etc. 2. Mainframe computers utilize their power in handling many users at a time. 3. Supercomputers utilize their power in solving a particular problem in a faster manner. 4. There exist portable computers like laptop, palmtop etc. They all have the capability to work on battery power.
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5. Real-time systems have to produce output within the particular deadline. 6. There exist two types of real-time systems: hard real-time systems, soft real-time systems. 7. Transaction processing system handles each transaction as an atomic unit. 8. There exist two types of client namely thin client and rich client. 9. Keyboard is a character input device used. There exist two types of keyboard called mechanical keyboard and membrane keyboard. 10.
The mouse is a pointing device. The two types of mouse are ball
mouse and optical mouse. The number of buttons on the mouse may vary. A scroll wheel can also be there in mouse. 11.
Touch pad is also a pointing device primarily associated with
laptop computers. 12.
Track ball is the upside down version of mouse. The ball can be
controlled by fingers directly. 13.
Storage devices are of two types. They are primary storage and
secondary storage. 14.
Primary storage is volatile in nature. The contents would be
erased if the power is switched off. 15.
Secondary storage retains the contents permanently. (They are
non-volatile in nature) 16.
There exist many secondary storage devices like hard disk,
compact disk, magnetic tape etc. 17.
Secondary storage can use different technologies like magnetic
memory, semiconductor memory, optical memory etc. 18.
Inside the hard disk there is a unit called head which is used to
read and write the contents. 19.
The storage area is divided into tracks and sectors.
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20.
You need to install a file system before using the storage device.
There exist many types of file systems like FAT32, NTFS, EXT 3 etc. 21.
Hard disk uses different technologies like SCSI, ATA etc.
22.
Floppy disk is available in various sizes. The capacity of 3.5
inches floppy disk is 1.44 MB. (Only the 3.5 inches floppy disks are used today. Generally the usage of floppy disk is diminished). 23.
In the case of compact disk laser light is used to read and write
the contents. 24.
The improvement over compact disk is the Digital Versatile Disk
(DVD). DVD has higher capacity than the compact disk. 25.
Magnetic tape is primarily used for backup purposes nowadays.
26.
Flash memory has become the de-facto standard for portable
memory today. 27.
There exist two types of display devices like Cathode Ray Tubes
and Flat panel. 28.
Cathode Ray Tube consumes higher power than the flat panel
displays. 29.
In flat panel display, there are various types like LCD, plasma
display etc. 30.
Printers are the hardcopy output devices. There are two types of
printers. They are impact printers and non-impact printers. 31.
Dot-matrix printer is an example for impact printer. The
operational cost of dot matrix printer is lesser. They are slower in printing. 32.
Laser printers are widely used nowadays. Tonners are used in
laser printers for printing. 33.
There are different types of plotters like pen plotters, electrostatic
printers etc.
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Self Assessment Questions 19.
FLOPS stands for a) Floating Point Operations Per Second b) Floating Operators Service c) Flying object services d) All of the above e) None of the above
20.
Real time systems a) Works in off-line mode. b) Have to adhere the deadline. c) No memory is required d) All of the above. e) None of the above.
21.
The display associated with Laptop is/are a) Flat panel display. b) Cathode display. c) Paper display. d) All of the above e) None of the above
22.
Which of the following is not a type of keyboard a) membrane keyboard b) mechanical keyboard c) raster keyboard d) all of the above e) none of the above
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23.
Which of the following is/are pointing device(s) a) mouse b) touch pad c) track ball d) all of the above e) none of the above
24.
Which of the following is an upside down version of mouse a) track ball b) touch pad c) tablets d) all of the above e) none of the above
25.
SCSI stands for a) Small Computer System Interface b) Simple Computer Software Interface c) System Controlled Software Identification d) All of the above e) None of the above
26.
Compact Disk is based on a) magnetic principles b) optical principles c) semiconductor principles d) all of the above e) none of the above
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27.
Which of the following is used in laser printers a) carbon papers b) ink c) tonners d) all of the above e) none of the above
28.
Which of the following is not plotter type a) Electro static plotters b) Thermal plotters c) optometric plotters d) all of the above e) none of the above Part II (Short Questions)
What are hard real time systems? Write short notes on palmtops. Write short notes on track ball. What are two types of keyboards? Write short notes on dot-matrix printers. Explain in short about CRT. List out various types of plotters. Write short notes on flash memory. Part III (Long Answer Questions) 19.
Explain various architectures of computers.
20.
Elaborate on various types of storage devices.
21.
Define hardcopy. Explain various types of printers in detail.
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Answer Key Part I 1. a
2. b
3. a
4. c
5. d
6. a
7. a
8. b
9. c
10. c Part II
11.
Hard real-time system is a type of real-time system where the task must
be finished within the deadline. If the deadline is not adhered the output would have no meaning. For example a system controlling the air traffic. Here the deadline is vital. 12.
Palmtops are portable computers. They are smaller than the laptops. As
the name indicates you can have them in your palm to operate. Palmtops can connect to internet in Wi-Fi mode. (Since a wired connection is not helpful in palmtops) 13.
Track balls are upside down versions of mouse. They are pointing
devices. Track balls used to situation where the finer control is required. 14.
Keyboards are character input devices. There exist two types of
keyboards. They are called mechanical keyboard and membrane keyboard.
15.
Dot-matrix printers belong to impact type. The running cost of dot-
matrix printers are very less (The cost per page is less). Dot-matrix printers are comparatively slower.
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16.
CRT stands for Cathode Ray Tube. CRT consumes higher power than
other devices like flat panel. At the same time the image quality of the CRT display is finer. 17.
There exist many types of plotters. They are thermal plotters, electro-
static plotters, pen plotters, ink-jet plotters. 18.
Flash memory is used with many devices today like mobile phones,
digital camera etc. Flash memory belongs to EEPROM type. The flash memory is a semiconductor based memory.
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Lesson 4: Introduction to Computer Networks Introduction
Every one of us uses the computer networks in our daily affairs, knowingly or unknowingly.
Known examples are booking of a railway ticket reservation, ATM for banking transactions etc.
So it is no wonder that computer networks forms the major and critical portion of Information technology world.
This lesson would elaborate on the computer networks
Objectives
Explaining the benefits of computer Networks
Introducing various types of Computer Networks
Highlighting the network components
Explaining various types of network topologies
Introducing Network protocols
A Computer network can be defined as the collection of interconnected computers that can communicate with each other. A computer network consists of collection of computers that are interconnected with each other. It is not always necessary that all the interconnected computers are of same type i.e. a network can consist of computers that belongs to various configurations. Another point to consider here is that the computers that are connected to the network may be located geographically far away.
4.1 Benefits of Computer Networks Computer networks provide us various benefits. This section would elaborate on various benefits of computer networks. The major benefits of computer networks are as listed below:
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Sharing of critical peripheral devices
Easier communication
Software sharing
Search-ability of data
Remote and Grid Computing features
Protection of data
4.1.1 Sharing of critical peripheral devices The primary advantage of computer networks is sharing of critical peripheral devices. Let us consider the following scenario: An organization is having more than thousand computers. It would become very costly to attach a resource like laser printer to each system. In such a case network connectivity would be very helpful. To manage this situation what you can do is attaching a printer to the network and providing the access to this printer to authorized users connected to the network. Apart from reducing the cost this solution provides another important advantage that now the resource can be controlled for valid access. The access rights can be set for the printer so that the users who are having access rights can access this printer. The resource sharing can be applied for many of the costlier resources like high resolution scanners, high capacity disk drives etc. By this strategy the maintenance of these resources also becomes easier. For example you can easily generate the access log for all the users who have used printer. You can also find out information like which file they have taken printout or scanned etc. On the other hand you are maximizing the usage of particular resource i.e. if there exits individual peripherals there is a possibility that they would be idle for majority of time. So the networks also make the optimal usage of peripheral devices.
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4.1.2 Easier communication Communication between the systems connected to a network would become easier. Consider the following scenario: If you want to copy a file from one machine to another machine and if there is no network exists then you have to depend on the removable storage medium like CD ROM or Floppy or USB drives. If the size of the files that you want to copy is huge then this solution would become much difficult. At the same time if those systems are networked it becomes much easier to transfer the file from one system to another. In a typical organization there would be lot of announcements or circulars running around. If the organization‟s computers are networked then these information can be easily transmitted to the required users. One of the most popular communication techniques that is been used all across the globe is e-mail (Electronic Mail). Through this e-mail you can transfer information from any part of the globe to any other part within seconds provided both the computers are having the access to internet. 4.1.3 Software sharing In an organization major portions of employees may require similar software. If you want install software in individual machines that would again become costlier. To manage this you can make the software sharable. This sharing is tightly linked with the sharing of data. If everyone is having their own copy of data there is a possibility of integrity failures meaning in one system data would have been updated and another system may not have updated the data. In such a case if decisions are taken with the old data it can certainly affect the business. 4.1.4 Search-ability of data Today we are living in a world which is overloaded with lots of data. Though much data is available it would be waste if you cannot access the
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desired information or data. The networks provide an avenue using which you can easily search the data. Though the network itself doesn‟t has the facility to search data but it certainly acts as the platform on which search applications can be easily developed. In other words if there is no network then search engines would not make any sense. So this Search-ability (search + capability) of networks is another important benefit of networks. 4.1.5 Protection of Data Without networks the data would reside on individual systems or desktops. The data residing in these types of machines have only limited protection. If you have business sensitive data then you can‟t afford to take the risk of simply putting them on a desktop PC with limited security. If you introduce network in this scenario then you can place the business critical data in to servers which have enriched security mechanisms. By this your data becomes protected. One more advantage of having network is the ability to take backups easily. Another factor is that you can place critical information in more than one server which may be located geographically faraway. The advantage of this is the protection from natural calamities like flood, fire, earthquake etc. 4.1.6 Remote and Grid Computing features If you have a task which requires high speed computing and if you don‟t have computer with matching capacity then you can rely upon the technologies like remote computing and grid computing etc. Using these technologies the powerful computing facilities located faraway can be harnessed for executing your tasks. Of course for this you should come to an agreement with the owner of that remote machine. These facilities have become possible only because of networks. If no computer network exists then you can‟t even think of these features.
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For example grid computing brings the ideas of how the electricity is been distributed with the help of power grids, to the computer science paradigm. Here you may not be aware of the fact that from where the computing power is coming from, very similar to the fact that you normally don‟t care from which resource the electricity is coming from. In coming years this grid computing can really the change the way in which the computer resources are perceived today.
4.2 Types of Networks On the basis of geographical coverage computer networks are classified in to three types. They are as listed below:
Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)
4.2.1 Local Area Network (LAN) Local Area Network (LAN) generally covers a small geographical range like one building or one office or a campus. These types of networks are popularly used in many of the organizations for above said benefits. LAN doesn‟t require the public telephone lines. Since the coverage is very less you can use your own private cabling system to connect the computers together in a LAN. The LAN can also use wireless technology. In such a scenario it is called Wireless LAN or WLAN. Both the Wired and Wireless have their own merits and demerits. It is the role of the network manager to decide whether to go for the wired LAN or Wireless LAN. Wired LAN can use twisted pair cabling or co-axial cable or even fiber-optic cables. In the case of Wireless you can use Bluetooth or infrared or Wi-Fi. Though there are variety of software to manage LAN, Netware from Novell is one of the popular software to manage LANs.
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Normally the LAN connections are faster. The reason for this is the usage of private cabling system to interconnect computers in a LAN. If a public telecommunication line is used there is possibility of disturbances in the line which is not there in the case of LAN. When a LAN is very small in size, simply connecting two machines and a printer for example, it would be called Tiny Area Network (TAN). These TANs would be very much helpful in the case of home networking where the number of computers and peripheral are normally very less in number. 4.2.2 Metropolitan Area Network (MAN) Metropolitan Area Network (MAN) spans across a city. Consider the following scenario: An organization is having ten branches across a city and it wants to connect all the branches together. In this case you cannot use LAN because of the larger geographical coverage but to use MAN. MAN would normally use Fiber-optic for its communication. Another mode of communication is the wireless communication in MAN. The fiber-optic communication would be reliable than the wireless communication. But it would be a tedious process to setup the fiber-optic cables initially. Once the initial setup is over fiber-optic communication can be very effective. If you plan to use Wireless communication in MAN then you cannot use similar technologies which are used in LAN like Bluetooth etc because of the larger geographical coverage. In this situation you can go for the microwave or radio communication across various units of MAN. 4.2.3 Wide Area Network Wide Area Network (WAN) covers a larger geographical area such as a country or the world. In the case of WAN the primary mode of communication would be Satellite communication. Since the coverage may span across many countries if not continents, satellite mode of communication seems to be very
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effective with the Wide Area Networks. WAN normally uses the combination of more than one communication technique like fiber-optics and satellite etc. In the case of WAN the public telecommunication systems are used because it would become much costlier to establish a private communication link across the country. Routing plays a crucial role in WAN. Since the geographical area is much larger it requires specialized techniques to transmit a packet (a data unit) from the source computer to the destination computer.
4.3 Network Components To get a clear understanding about networks it becomes necessary that you should have an idea about various components of computer networks. This section would provide an introduction to these components. They are as listed below:
Connecting Media: The primary purpose of network is communication. To establish the communication you require a medium. This medium can be wired or Wireless. For example Fiber-optics, coaxial cables, twistedpair cables are wired communication media. Bluetooth, Infra-red, Wi-Fi are example of wireless medium. The choice of medium depends on the scenario.
Network Interface Cards (NIC): If you want to link a computer to a network (wired) you would require a specialized hardware called Network Interface Card (NIC). These NIC are normally inserted in to extension slots of mother board. The external NIC are also available which are not popularly used.
Network Management Software: To manage a network you would require specialized software. There exist a special category of operating systems called NOS (Networking operating Systems). The network monitoring tools can be used to monitor the behavior of the network.
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Networking devices like Bridges, Gateways, Routers, Modems and Wireless access points: If you would to link more than one network together “bridges” are required. Bridges are used as an interface between same types of networks. Gateway is also an interface which would link different kinds of networks. Routers are used to direct the data packets so that they can reach the proper destination. Modems are specialized hardware that performs the tasks of modulation and demodulation. They are used to convert analog signals to digital and vice-versa. Wireless access points are used to wireless networks to provide access points to the systems connected with that network.
4.4 Network Topology Topology of a network can be defined as the layout of the network i.e. the logical shape that the connection between various nodes forms. Selection of topology of a network is also a critical factor in the proper functioning of network. There exist various network topologies. They are as listed below:
Bus Topology: In the case bus topology there would be one communication channel running common across all the nodes. If this common channel breaks then the connectivity of the network would not be proper. This is illustrated in the Figure 4.1 Figure 4.1: Bus topology
Star topology: In star topology there would be a central node to which all other nodes are connected as shown in the Figure 4.2. The advantage of star network is that if one connection breaks then it doesn‟t affects other nodes. Figure 4.2: Star topology
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Ring Topology: Here all the nodes are connected in a manner so that it forms a loop or circular connection. In ring topology itself you have single ring and dual ring network. Double ring or dual ring topology allows connections in both the directions. Example for single ring and dual ring topologies are shown in Figure 4.3 and Figure 4.4 respectively. (N1, N2, N3… stands for Node 1 , Node 2 etc )
Figure 4.3: Ring (single) topology
Figure 4.4: Ring (Dual) topology
Mesh topology: Mesh topology connects each node in the network to every other node. So there exists a direct link between any two nodes in the network. Mesh topology is very strong because of the fact that there is a direct connection between any two pair of nodes. Simplest of mesh topology is a triangular shaped network which is shown in the Figure 4.5. The mesh topology shown in the figure may look simple but when the number of nodes increases the count of connections increase in a rapid manner. So it is complicated to construct the mesh topology.
Figure 4.5: Mesh topology with 3 nodes
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4.5 Network Protocols Protocols are the set of rules that are to be followed in a network communication. In other words we represent a protocol as language of networks. There exists variety of protocols available for networks. A survey of all such protocols would be out of scope of this text. So here you will find a simple introduction to protocols that are widely used in networking paradigm. Why do we actually need protocols? This is an interesting question. The answer for this question is as follows: Each computer connected to the network may be using different operating system or their hardware configuration may be entirely different. If they want to establish connection among them, then they have to follow certain commonly accepted rules. These commonly accepted rules are nothing but the protocols. This term protocol you would have heard in domains other than computer science. Every where it defines a set of agreed upon rules which have to be followed while making interactions. The below given is a list of popularly used protocols in the computer network paradigm:
TCP
- Transmission Control Protocol
IP
- Internet Protocol
SNMP
- Simple Network Management Protocol
SMTP
- Simple Mail Transfer Protocol
FTP
- File Transfer Protocol
IMAP
- Internet Mail Access Protocol
HTTP
- Hyper Text Transfer Protocol
From the name of the protocol itself you can get an idea about the role of that protocol. Apart from the protocols given in the above list there exist various other protocols.
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Summary
A computer network consists of more than one computer connected together.
Computer networks provide various advantages like sharing of devices, communication, data security etc.
There exist many types of networks. For example LAN, WAN, MAN.
LAN stands for Local Area Network. The scope is limited to within a building. Generally the coverage is shorter.
MAN is Metropolitan Area Network. It would cover an entire city. When an organization has many branches across a city MAN would be used to link the various branches.
WAN is Wide Area network. The coverage is across a country or continent.
There exists one more type of network which is called internet. Internet is a global scale network.
There exist various components in a network. For example connecting media, network management software, bridges, gateways etc.
Bridge is used to establish connection between similar type of network.
Gateway is used to establish connection between different types of networks.
Topology refers to the structure of a network. There exist many different types of topologies.
In bus topology all nodes are linked to a common bus.
In star topology there would be a central computer to which all other computers would be linked.
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In ring topology the computers are connected in a circular manner. There exists a variation of ring topology which is called dual ring. Self Assessment Questions Part I (Multiple Choice Questions)
Network benefits includes
Sharing of devices
Easier communication
Remote access capability
All of the above
None of the above
LAN stands for
Local Area Network
Legal Access Network
Local Access Nodes
All of the above
None of the above
If the network has to cover an entire country then which of the following is/are the correct choice(s)
Local Area Network
Wide Area Network
Global Area Network
All of the above
None of the above
The topology where all the nodes would be connected to a central computer is called
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Ring topology
Centre topology
Star topology
All of the above
None of the above
Which of the following is/are not network protocol(s)
HTTP
FTP
SMTP
All of the above
None of the above
A topology in which direct connection between any two nodes exist is called
Mesh Topology
Star Topology
Bus Topology
All of the above
None of the above
NIC stands for
Node Integral Centre
Network Integral Centre
Network Interface Card
All of the above
None of the above
Internet is
a global scale network
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network of networks
uses protocols like http, ftp etc
all of the above
none of the above Part II (Short Answer Questions)
Define computer networks.
Write short notes on LAN.
What do you mean by protocol?
Write short notes on star topology.
Explain about NIC.
Write short notes on WAN. Part III (Long Answer Questions)
Explain various benefits of computer networks.
Explain in detail about LAN, WAN, MAN.
Define Topology. Explain different types of topologies. Answer Key Part I
1. d
2. a
3. b
4. c
5. d
6. a
7. c
8. d
Part II
Computer network is collection of interconnected computers. Network provides various advantages like sharing of resources, communication etc.
LAN stands for Local Area Network. LAN boundary is limited to a smaller geographical area. It is within only a building or an organization.
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Star topology is an arrangement where all the nodes are linked to a central computer. All the nodes would have the direct connection with the central computer.
NIC stands for Network Interface Card. If you have to connect your system to a wired network then your system should have NIC. The network cable would be inserted in to the port provided in NIC.
WAN stands for Wide Area Network. WAN can covers a large geographical area like a country or continent. WAN network generally uses the existing telecommunication lines for connectivity.
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Lesson 5: Software Introduction:
Software is the key component of any computer system.
It is the software which makes computers useful.
Software can be defined as a set of instructions that tells the computer what to do.
Without the software a computer cannot serve any useful purpose for which it is been intended for.
The software instructs the computers about how to perform a particular task in a very detailed manner.
In real time, combinations of software are sometime used to achieve the goal.
Objectives
Introducing the characteristics of software.
Explaining various classifications of software.
Introducing operating systems.
Explaining about various types of operating systems.
5.1 Characteristics of Software The instructions provided by the software to the computer possess certain characteristics. These instructions are
Unambiguous in nature
Able to perform only the tasks for which they are intended for.
May require certain pre-requisites to be satisfied before execution. In today‟s scenario almost everybody knows about the term software in
one or other means. Nowadays the buzzword in any industry is automation which refers to the process of application of computers to do the work in an enriched way which was done earlier with much of human efforts. Software
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facilitates this task. Knowingly or unknowingly, software plays a role in every individual‟s life, living in the modern era.
5.2 Classification Software is generally classified in to two types. They are
Application software
System software
Utility programs Let it be any kind of software, it posses the characteristics explained in
the earlier section. In this section we will elaborate in to the details of all these classes of software. 5.2.1 Application Software: Application software is a class of software which is used to solve the problems specific to a particular domain. In other words these are the software that are developed to accomplish certain kind of activities like mathematical calculations, drawing graphics, document drafting and printing etc., We can define application software as follows: Application software is a class of software that is used to accomplish specific tasks not related to the computer itself. To elaborate more, this software is used to perform a task that is specific to a particular domain. 5.2.1.1 Classification of Application Software Application software is classified in to following categories. They are
Horizontal Market applications
Vertical Market applications
Custom Applications
Shareware and freeware
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5.2.1.1.1 Horizontal Market Applications Horizontal market Application software is not specific to a particular industry. For example we can consider a spreadsheet application (like Microsoft Excel) which is not specific to a particular industry. But it‟s been built for mathematical calculation based activities. Based on this we can use the designed application software to cater the needs of the end-user (End-user is a class of users who does not know about the internal happenings of the computer systems but mainly concerned about the tasks in hand to be completed). Like this any word processing application is an example of application software. A word processing application is a generic application to draft, format and print documents. The usage of horizontal market applications is dependent on the end-user who is using it. 5.2.1.1.2 Vertical Market Applications Vertical market applications are specific to a particular industry. For example software designed to mix the paints to get a particular color can be only used in that industry. Another example for vertical market application is quality tracking in textile industry. The idea of automation that is specified previously mostly belongs to the Vertical market application class. 5.2.1.1.3 Custom Applications Custom applications are tailored for a particular organization. These kinds of applications addresses the issues related to the particular organization. Custom applications have certain pros and corns. The merits of custom applications are
Addresses specific issues
Optimized to produce results faster and accurate.
Cost effective
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The demerits of custom applications are
Lengthier development time
Increased cost of application An example for custom application is the online train ticket reservation
system which is very specific to the railways. It is one of the applications which is been used widely in our country today. 5.2.1.1.4 Shareware and freeware Shareware are software that you can try before you buy. The shareware are initially distributed freely. If the users who are using it are satisfied with this they have to pay. Normally in many shareware applications certain features are either not available or available only for a limited duration of time. After that particular duration (or number of uses) it becomes unusable fully or partly. Freeware is the short form of free software. Freeware are software that is completely free of cost to use. In contrast to shareware, freeware are absolutely free. 5.2.2 System Software The next class of software is System software. In contrast to application software, system software is mainly used as an intermediate layer between the application programs whatever we install and the hardware of the computer. One of the well known examples for system software is Operating system which would be discussed in detail in the later section. System software can be defined as follows: System software is a class of software that is used to accomplish specific tasks related to the computer itself. System software manages and controls the hardware so that application software can perform their designated task. In other words system software can be characterized as application independent software i.e. system software is not specific to any of the
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application programs. At the same time system software ensures the functionality of other application software. System software directly interacts with the hardware of the computer. Most of the times, system software is more complex than application software. Any bug in the system software has increased possibility of making the system unresponsive. Most of the computer users would have experienced this when the operating system suddenly throws a fatal error and the system stops functioning. If the system software is directly stored in the chip itself (usually by the manufacturer) then it is termed as firmware. Well known example for firmware is the BIOS (Basic Input Output System) found in the IBM compatible personal computers. 5.2.3 Utilities Utility programs are another class of software. An utility program can be defined as follows Utility programs are a class of software that is used to accomplish frequently performed tasks that may be common to many applications or to do with the system functions such as performance tuning etc., So by this nature the utility programs can be helping programs for application software or system software. So here we have made them a separate classification. Examples for applications related services provided by utilities are copying, sorting, merging etc Examples for system related services provided by utilities are file recovery, formatting, disk diagnosis etc Utility programs come in handy when we want to perform some tasks frequently but they are not provided by the operating system itself. By this, utility programs support the operating system by providing some additional services.
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Utility program differs from general application software in some characteristics like size, complexity and function. For example, we cannot term a general word processing application as utility software because they are huge in size and more over they have certain features which are complex to perform. The utility program extends capabilities of both system software and application software. If we have specific utility software available for performing a particular task then it would be very easy for the user to perform that task. Utility programs can be proprietary, shareware or freeware. Utilities which are freeware or shareware are easily downloadable from internet. The proprietary utilities need to be bought from the companies who have originally developed these utilities Nowadays we have utilities to perform wide variety of tasks like data recovery etc.
5.3 Operating System Operating system belongs to the system software classification. It plays an important role in the functionality of any computer system. Operating system can be defined as follows: Operating system can be defined as software that manages the computer system. It also acts as an interface between the user and computer hardware. All the modern day computers have an operating system. This implies that, in the early stages of computers there were systems which doesn‟t had a well defined operating system. In such cases the users of those computers needed to perform a whole lot of supporting tasks in order to complete the task that he/she wanted to do. After the development of operating system the user can concentrate completely on the task which he/she wants to do. An operating system can be compared (roughly) with the government. The role of a government is to manage the resources in the country so that the
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resources can be utilized optimally. Similarly an operating system shares the resources available to each of the process that are running in the system. On the basis of managing the resources operating system can be compared to government. Another important responsibility of operating system is to behave as an interface between user and computer hardware. As we all know computers can understand only binary (0 and 1) language. This binary language can not be understood by humans. Instead we use high level languages like English. So it is the responsibility of operating system to translate the instructions provided by user in high level language to machine language and again covert the machine language result to the human understandable language. This is the ultimate task that any operating system has to perform. Fig 5.1: Operating System as an interface between user and computer Operating system acts as a translator between the user and the computer. It translates from user language to machine language and vice versa. Apart from this translation operating system performs a wide variety of tasks which are explained in the next section. 5.3.1 Basic Functions of operating system Operating system performs a wide variety of functions. In this section we would elaborate on these functions which are performed by any operating system. They are listed below
Process Management
Memory Management
I/O Management
Disk & File system Management
Security
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Networking services
5.3.1.1 Process Management A process is nothing but a program in execution. Being a manager of computer system operating system has to manage these processes. Any computer which has a single CPU would be able to execute only one process at a time. But we all know that almost all the modern day computers are capable of executing many processes at the same time. How this becomes possible? The basic fact that a processor can execute only one process at a time cannot be modified. It is the operating system which makes us “feel” like many processes are simultaneously running in the system. This becomes possible by the process management capability of operating system. The operating system allocates each process some units of processor time so that they can perform their task. There exists a wide collection of algorithms for selecting the processes. Almost all the modern day operating systems have this capability of scheduling multiple processes. During the process management operating system has to take care of certain criteria like no process should indefinitely wait for execution. Operating systems also provide priority based process scheduling because at times we want certain processes not be interrupted or to be given higher priorities. 5.3.1.2 Memory Management Another important role of operating system is the memory management. A process cannot be executed unless until it is provided the required memory i.e., if only the processor is allocated to a process without required amount of memory then the execution is not possible.
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Memory refers to a generic term which includes many types ranging from the register memory to secondary memory devices. Memory manager according to the condition allocates the required type of memory to the processes (By swapping the contents from one type of memory to another). Most of the modern day operating system supports the concept of virtual memory i.e. the memory that does not exist as it is but logically available for the process for its execution. In such a scenario operating system has to manage the virtual address also. It requires mapping it with the physical address etc. In order to manipulate virtual memory the operating system uses some sort structures like page tables. 5.3.1.3 Input / Output Management User can not interact with the computer unless until he/she has the input and output devices. Input devices include keyboard, mouse, digital pen, touch screen etc. Similarly output devices includes screen, printer etc. First and foremost thing in input / output management is that any device that is connected to the system should be recognized by the operating system in order to either receive input from it or sending output to that device. Operating system has to keep track of what devices are being connected to the system. On top of this it has to also monitor whether these devices are active and accessible. In order to cope with the device from many manufactures corresponding device drivers are loaded to facilitate proper functionality. 5.3.1.4 Disk and File System Management Since the primary memory is limited in size and it is volatile we need Disks. The disk memory usually called as secondary memory is non-volatile in nature and also comparatively huge in size. Operating system has to manage these secondary storage devices i.e. disks also. Unlike the primary memory i.e., RAM, disks need to be formatted
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before being used. Many operating systems provide utilities to perform this formatting task (otherwise third-party tools have to be used). Operating system also needs to manage the free space in the disk so that while allocating storage for future request it can choose the best available locations. There exists a wide variety of algorithms for this like first fit, best fit etc. To handle the disks operating systems maintains the file allocation table normally called FAT. The operating systems provide support for variety of file systems like FAT32, NTFS, and HFS+ etc. Since the disks are very slower when compared to the speed of processor, the operating system needs to manage these disks in an efficient manner so that delays can be reduced to a maximum possible extent. 5.3.1.5 Security Security is the buzzword in today‟s IT industry. Security gets more focus because security and accessibility are inversely proportional. A computer‟s primary task is to provide access but only to the authenticated persons. Many operating systems provide security in one form or other. The resources need to be secured from both the internal as well as external access. A process which is executing inside the system itself is restricted only to access certain resources and not to all. For example no process is permitted to overlap the memory where operating system resides. This is also a form of security. Similarly, operating system also provides some security mechanism to protect the unauthorized access of resources from outside the computer system. Many of the modern day‟s operating systems include specially designated software for this purpose called Firewall (in a network scenario).
5.3.2 Classifications of Operating Systems
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Operating systems can be classified on the basis of many of the characteristics. So it becomes mandatory that we need to discuss these factors before actually entering into the actual classification itself. Below given are some of the critical factors that can be considered while doing the classification.
Task count
User count
Portability
Machine Type
5.3.2.1 Task Count Task count is the most important factor used to classify the operating systems. Task count refers to the number of tasks that can be handled by the operating systems at a particular instance of time. On the basis of task count we can classify operating system in to following types. They are
Single Tasked operating systems
Multi tasked operating systems
5.3.2.1.1 Single Tasked Operating system A single tasked operating system can handle at the maximum of only one task at a time. In other words, we can execute only one task at a time. Olden day operating systems mostly belonged to the single tasked category. Well known example for single tasked operating system is the Disk Operating System (DOS) released by Microsoft. 5.3.2.1.2 Multi Tasked Operating System In contrast to the single tasked operating system, multitasked operating systems can handle more than one task at a moment i.e. we can have multiple
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processes running in the system at the same time. Many of the modern day‟s operating systems belong to the multi tasked category. In multitasking we have further sub-categories. They are 1. Preemptive Multi tasking 2. Cooperative Multi tasking In the case of preemptive multitasking operating system slices the processor time to each of the processes running in the system. In this case it is possible that the operating system can forcefully pause (even stop permanently) a process before it completes its execution Examples for this type of operating systems are OS/2, Windows 95 etc. In the case of cooperative multitasking, each program can control the CPU as long as it wishes. At the same time if the process is not using the CPU then it can allow some other process to utilize the processor. Examples for this kind of operating system are Windows 3.x and MultiFinder for Macintosh computers.
5.3.2.2 User Count User count refers to the number of concurrent users allowed to access the system. On the basis of user count, operating systems are classified as follows
Single User operating system
Multi user operating systems
5.3.2.2.1 Single User operating systems Single user operating systems allows at a maximum of only one user at a time to access. But it is not mandatory that the user can execute only one process i.e. a single user operating system need not be single tasked. For example the Windows 98 operating system is a single user operating system because it can allow only one user maximum at a time.
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5.3.2.2.2 Multi User operating systems Multi-user operating systems can allow „n‟ (n >=1) number of users at a time to access the system. The UNIX operating system is a well known example for multi-user operating system. Here we have the option for „rights‟ to different users. Rights refer to the permissions available to the users to perform a task. Operating system would have control over all such rights. So whenever there is a request for an operation, the operating system checks against these rights. If and only if the user has got that particular right then only he/ she is permitted to perform the task. Apart from the normal users the system would also maintain some system level users to perform system related tasks.
5.3.2.3 Portability An operating system is said to be portable if it is independent of the hardware. There are certain operating systems which are hardware dependent and they are called non-portable operating system. For example the MVS of IBM is an example for non-portable operating system.
5.3.2.4 Machine Type On the basis of which type of machines the operating system controls we can classify the operating system in to following categories:
Desktop Operating Systems
Server Operating Systems
Mainframe Operating System
Embedded Operating System
5.3.2.4.1 Desktop Operating Systems
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There are certain operating systems which are totally designed for personal computers. These Desktop operating systems are normally used in many of the machines where we don‟t need a greater extent of security. Microsoft‟s PC DOS is an example for one such system. 5.3.2.4.2 Server Operating Systems On the other hand we can‟t deploy desktop operating systems in a powerful server where we would require greater amount of security and enhanced process management techniques. There exist certain operating systems specially designated for such a purpose. Windows NT (NT is not network technology but New Technology) is one such server operating system. We have many variations of Linux which are widely used with servers. 5.3.2.4.3 Mainframe Operating Systems As the name indicates these operating system are used to work with main frame computers. Popular example for this kind of operating system was MVS which is used in IBM main frame computers. These main frame operating systems are comparatively secure and powerful.
5.3.2.4.4 Embedded Operating Systems Many of the devices that we use in our day-to-day life have a built-in microprocessor attached with it. For example washing machines have their own processor to control the operations. In order to handle this microprocessor we have a built in operating system which is called embedded operating system. These operating systems need not have all the capabilities of a modern day operating system but it would have the features necessary to work with that particular system. Microsoft‟s embedded DOS is an example for this kind of operating system
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Summary
Software is the logical component of computer system.
Software provides set of instructions for the computer to accomplish a task.
Software possess certain characteristics like unambiguous in nature etc.
Software can be classified into various types like application software, system software etc.
Application software is used to solve particular type of problem. There exist many types of application software like horizontal market application software, vertical market application software etc.
Freeware refers to the software which can be used without paying any money.
Shareware is similar to freeware with many restrictions like usage till a particular time, with limited features etc.
Operating system is system software that acts an interface between user and the system.
Operating systems can be classified into many types based on various factors. For example user count, process count etc.
In the case of multi tasked operating systems there are two types. They are preemptive multitasking, cooperative multitasking.
Operating systems have two types of user interfaces. They are character user interface, graphical user interface.
Operating system performs various tasks like process management, memory management etc.
Operating systems used with hand held devices are called embedded operating systems. There exist many embedded operating systems.
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Self Assessment Questions Part I (Multiple Choice Questions)
Which of the following is not a classification of software
System software
Application software
Tech software
All of the above
None of the above
Which of the following is not an application software
Banking software
Railway reservation system
Operating system
All of the above
None of the above
The software which you can access for limited time period or with limited features without paying any money is called
Shareware
Partware
Miniware
All of the above
None of the above
Quality tracking software used in textile industry belongs to
Horizontal market application
System software
Vertical market application
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All of the above
None of the above
Disk formatting tool is an example for
Utility software
Ambiguous software
Miniware
All of the above
None of the above
The system software that acts as an interface between user and computer is called
Linker
Loader
Operating system
All of the above
None of the above
Which of the following is not a type of operating system?
Embedded OS
Multi user OS
Set OS
All of the above
None of the above
The Operating system which can be installed in portable devices is called
Embedded OS
Port OS
Micro OS
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All of the above
None of the above
Macintosh OS is an example for
Character User Interface
Graphical User Interface
Open Source
All of the above
None of the above
Which of the following is not a file system
FAT 32
NTFS
EXT 3
All of the above
None of the above Part II (Short Questions)
Write short notes on software.
Explain in short about “custom applications”.
What do you mean by utility programs?
Define operating system.
On the basis of task count how operating system can be classified?
Differentiate freeware and shareware.
What do you mean by memory management?
What are two types of multitasking?
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Part III (Long Answer Questions)
Explain various classifications of software in detail.
Elaborate various functions of operating systems.
Explain the classifications of operating systems with clear examples. Answer Key Part I
1. c
2. c
3. a
4. c
5. a
6. c
7. c
8. a
9. b
10. e Part II (Short Questions)
11. Software is the logical component of computer system. Software instructs the computer what to do. Software makes the computer usable. 12. When an organization develops an application from scratch to meet the needs then it is called custom application. Custom application is costlier in nature. 13. Utility programs are a class of software that is used to accomplish frequently performed tasks that may be common to many applications or to do with the system functions such as performance tuning etc., 14. Operating system can be defined as an interface between user and the system. It is the operating system which makes the user to work with the computer efficiently and easily.
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15. On the basis of task count, operating system can be classified into two types. They are single tasked and multi tasked. Multi tasking itself can be further classified into cooperative and preemptive multitasking. 16. Freeware refers to the class of software which can be used with out paying any money. Shareware can be used freely but for a limited period of time or with limited set of features. 17. Operating system has to manage the memory among the processes running in the system. To manage memory there are many techniques like virtual memory etc. 18. Multitasking refers the capability of handling multiple processes at the same time. There are two types of multi tasking. They are preemptive and cooperative multitasking.
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Lesson 6 : Programming Languages and Packages Introduction
A language is nothing but a tool for communication.
We, human beings use the natural languages like English, Hindi etc to communicate with others.
Similarly there is a need for a tool to communicate with the computer. Such a tool or language to communicate with the computer is called programming language.
As we have already seen, a program is nothing but a set of instructions written to complete a particular task. These instructions are written in a language called programming language.
Package is defined as software that performs some well defined functions.
In order to use the package the user need not be a programmer. So the target audience of the package is generally non-programming users.
Objectives
Introducing the paradigm of programming languages
Explaining various generations of programming languages in terms of their advantages, disadvantages and usage.
Explaining about various tools associated with programming languages, like assembler, compiler and interpreter.
Introducing the concept of packages.
Highlighting the spread sheet applications, their components and usage.
Introducing the presentation tools.
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Introducing the Desktop Publishing Tools (DTP)
Elaborating various applications areas of software. For example commercial, scientific and real time etc.
6.1 Programming Language – The Definition So a programming language can be defined as follows: A programming language is defined as a standardized tool for communication with a computer. There exist plenty of programming languages available. Each and every programming language has its own specialized areas where they can be effectively applied. Programming languages went through a well structured growth in parallel with the growth in computer hardware. In parallel to the grammar of our natural languages computer languages do have a set of rules. These rules define the syntax of the programming language. In fact these rules are much strict than the rules of human language. Even though we make some mistake in the grammar of human language we are able to understand but the computer will not be able to understand the language even if a small syntax error is there. In the next section we would elaborate about various generations of programming languages and their usage. 6.2 Generations of Programming Languages Programming languages are grouped into generations. The languages belonging to the same generation would have some common factors among them. In addition to this always the next generation language would have more advanced options than the current generation language. We have following generations of programming language.
First generation language
Second generation language
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Third generation languages
Fourth generation language
Fifth generation languages Let us elaborate the features of each of the generations of programming
language. We would also look through the advancement that had been made in each generation of language. 6.2.1 First Generation Language (1 GL) First generation language was very closest to the computer. They are called machine language. Machine language consisted of only two symbols. They are 0 and 1. So the programs written using machine language would have only these two symbols at the maximum. The most important advantage of machine language is that the programs written in machine language would execute fastest. The primary reason for this is that the processor can understand the language directly. At the same time the problem with first generation language is that human understanding of these languages is next to nothing. It would be easy to solve the most complex puzzle than understanding the program written in this language. For example let us have a sample program to add two numbers. If we want to write the program performing this task in machine language then we have to do the following things: Step 1: Identify the instructions available to load two numbers Step 2: Identify the instructions for addition Step 3: Find out the binary equivalent for these instructions The entity that makes the machine language hard to handle is the italicized term binary equivalent. Yes, we have to find out the binary equivalent of these instructions.
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Once after the program is developed in machine language it is very hard to maintain this. The maintenance becomes very hectic because readability of the code is very poor. Even though we have wide collection of programming languages today, computers can still understand only machine language. So whatever may be the language we use there should be a translation mechanism to convert this code to the machine language. 6.2.2 Second Generation Language (2 GL) Since the machine language programs are hard to write and maintain there was a need for an enhanced language which would increase the readability of the code and also it would be easy for the programmer to develop the program. All these efforts lead to the development of second generation language that is the assembly language. Assembly language is an improvement over machine language. In assembly language we need not code in binary i.e. 0 and 1. Instead we can use some sort of mnemonics. Mnemonic codes are nothing but the small words that represent the instruction. The word is chosen such that it would make sense. For example the mnemonic code for the addition operation can be ADD. This would be much better to understand instead of writing 0000 0001 1000 0010 which may represent the binary for addition. The programs written in assembly language are called ALP i.e. Assembly Language Programs. These assembly language programs would be comparatively easier to understand than the machine language. One of the important drawbacks of ALP is that, an ALP program is dependent on the microprocessor for which the program is written. There would be separate instruction sets for each of the microprocessor. So we cannot use (as it is) the code written for one microprocessor for another microprocessor.
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Even today certain programs are coded into ALP when speed is the primary criterion. Even some of the high level languages like C have provisions for inclusion of Assembly language instructions inside their own program. As we have already specified the computers can still understand only the machine language we should use a translator to convert from assembly language to machine language. For this purpose we have a translator called assembler. So an assembler can be defined as follows: An assembler is a translator which would translate the assembly language programs in to machine language programs. This procedure is depicted in the following figure 6.1. Fig 6.1: Role of Assembler We can do the ALP coding in more than one ways. One is through the microprocessor kits where we have to supply the hexadecimal op-codes for each instruction. Another way to perform this is through the debug mode in the command prompt of MS DOS. There we can directly type the ALP coding. Today we have some of the simulators available to work with the ALP. These simulators would provide a better editor and an inbuilt assembler simulation tools. Apart from machine dependence assembly language programs are quite handy in situation where we can not directly apply any high level language. 6.2.3 Third Generation Language Even though the ALP is much better than the machine language we cannot use them directly in all commercial application development. Primary reasons are machine dependence and the development time. It is practically impossible to develop the different source codes for different hardware.
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All these factors lead to the development of third generation languages which are called high level languages. The primary advantages of third generation languages are 1. Hardware independence 2. Increased readability Since these languages are independent of the hardware there is no need to develop an individual version of program for each hardware variation in consideration. One more fact is that the readability of these programs is much better than the assembly language programs. In fact one of the important factors that were considered during the development of these languages is that they should be closer towards the natural languages. Even though, there has been lot many high level languages only few of them are more popularly used. The below given table summarizes a few of popularly used high level languages and their usage Language
Purpose
ForTran
Engineering applications
COBOL
Business oriented applications
Pascal
Academic purpose (like explaining data structures)
BASIC
Introduction to programming languages
C
System programming
C++
Object orientation
Delphi
Commercial application development
Visual Basic
Commercial application development
Java
Internet programming; OS independent software development
Table: High level languages and their usage
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Apart from the languages given in the above table there exist a wide collection of languages which are used for plenty of other purposes. Hence the machines cannot understand any of the languages other than machine language; we need some translators to translate from high level language to a form that can be used for execution. We have two different types of translators available for this purpose. They are
Compiler
Interpreter A compiler is a translator that would scan the complete source program
written in a high level language and produce the object code output which would be stored for later execution. This is depicted in the following figure 6.2. Fig 6.2 : Role of compiler Well known examples for compiler oriented languages are C, C++, and COBOL etc. An interpreter would scan the program line by line and translate it for execution. The primary difference between compiler and interpreter is that, compiler stores its output file in the disk, where interpreter doesn‟t produce any intermediate files at all. The interpreter‟s mode of operation is depicted in the following figure 6.3. Fig 6.3 : Role of interpreter Well known example for interpreter oriented language is BASIC. The important point to note about interpreter is that it does not produce any intermediate file. Its output is direct execution of the high level program.
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Both compiler and interpreter have advantages as well as disadvantages. The primary advantage in compiler is the speed of program execution. The advantage with interpreter is lesser disk space usage. Now the disadvantages becomes obvious i.e. compiler would require additional disk space and interpreter programs would be slower in execution. Some of the modern day languages use a mixture of compiler and interpreter approach. For example Java where the source code is compiled to an intermediate form and then an interpreter would be used to execute that code. 6.2.4 Fourth Generation Languages Fourth generation languages are closer towards human languages. Fourth generation languages are mostly used with database querying operation. The ultimate aim of fourth generation language is that learning these languages would be much simpler than the high level languages. The code written in fourth generation languages would concentrate more on what to do? They would not have much detail about how to do that task. For example a statement in fourth generation language would be similar to this. “Fetch all students whose total mark is greater than 1100” Here the implementation details are hidden. It does not explicitly explain how to perform this task. But anybody looking at this code would get a fair idea of what this statement would do. 6.2.5 Fifth Generation Languages Fifth generation languages are mostly used with Artificial Intelligence and Neural Networks. The primary difference between fifth generation language and other languages is that, here we use constraints given to solve a problem, instead of using direct algorithm.
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Well known example for fifth generation languages are Prolog, OPS5 and Mercury. When the development of fifth generation languages started there were much expectations regarding this. Still the development in these areas is in progress. May be in the near future we can expect some awesome results from these fifth generation languages.
6.3 Packages Package is defined as software that performs some well defined functions. In order to use the package the user need not be a programmer. So the target audience of the package is generally non-programming users. Most percentage of the users of computers is non-programmers. They have plenty of tasks to perform. Some tasks may be common across a wide group of users. In such cases the software companies releases their software in a package. Package would be accompanied with a well defined documentation. The common benefits of using packages are plenty. Normally any package would be well tested before their actual release. So the probability of bugs (errors in the software) would be lesser. Because the documentation is provided with any package it would be easy for the user of these packages to get fair idea about working procedure with these packages. Moreover sometimes these packages are bundled together. In such cases they are called package suite or application suite. In this section we would explore many of commonly used package types. The structure of these packages and also their commercial usages would be described. The following are some of the commonly used types of packages
Spreadsheets
Desk Top Publishing (DTP) tools
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Presentation tools Let us explore each of these in detail.
6.3.1 Spreadsheets Almost every user of the computer would have known about this spreadsheet applications. We can easily say that spreadsheets are one of the most popular applications in the industry. In this section we would explore about the principles of spreadsheet and their applications.
6.3.1.1 Structure of Spreadsheet The following figure is a screen shot of a spreadsheet from Microsoft‟s Excel spreadsheet application. Fig 6.4: Spreadsheet (Microsoft Excel) In general spreadsheet is a rectangular arrangement of cells. In contrast to a normal documenting application we cannot enter the text anywhere in a spreadsheet; rather we can enter text only in the cells. Cell The smallest addressable unit of a spreadsheet is called cell (Refer fig). Each and every cell has an address associated with it. It is called cell address. A cell address normally would be a combination of row number and column numbers. For example the darkened cell in the above figure 6.4 is cell D5. Her „D‟ indicates the column number and „5' indicate the row number.
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Number of cells is a spreadsheet is normally huge. Only a portion of the spreadsheet would be displayed in the screen at a moment in time. We can view the other cells by scrolling through the spreadsheet. Formulae The most important advantage of spreadsheet is the usage of formulae. Formula can be defined as follows A formula in spreadsheet is a rule to derive the content of that cell. The result of the formula would be displayed in the cell. The result of the formula in a normal situation can be either numeric or text. In some abnormal conditions the result of the formula can be error also. The reason for this can be either a direct error in the formula or one of the supplied values for the formula may be missing or incorrect. In all the spreadsheet applications there would be some distinctions between the normal cell contents and the formula. For example an „=‟ sign can placed in front of the cell contents to indicate that it is a formula. Fig 6.5 : Spread sheet with a formula in the cell The above figure 6.5 depicts the spreadsheet with formula in the cell. The following figure 6.6 depicts the same scenario with result of the formula in the cell. Fig 6.6: Spreadsheet showing the result of the formula in the cell
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There are formulae available to perform variety of operations. Since the spreadsheets are primarily used with mathematical calculations more concentration is given to the mathematical formulae. 6.3.1.2 Applications of spreadsheet Mainly spreadsheets are used to perform mathematical and financial calculations. The primary advantage with spreadsheets is that the effects of a changing a particular number can be made automatically bubble through all the places wherever that particular cell is referenced. This is the major advantage of using the spreadsheets. This feature makes us to simulate many of the “what if” scenarios i.e. by changing a particular number we can identify the effects that would be caused by this change. This would be very much useful in budgeting kind of applications where all the numbers are interrelated. In such conditions we can immediately identify the effects of the change which is not quite easily possible if we use some other kind of applications.
Format Conditionally Unlike the normal word processing applications, in spreadsheets we can format the cells according a particular condition. For example we can make the contents bold if the value is greater than 6500. This is depicted in the following figure 6.7. In this example the cells having the value greater than 6500 are made bold. If we change the cell contents then the formats would be applied according to the condition. No additional effort is needed to make the formats to be applied accordingly
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Fig 6.7 conditional formatting Filtering We can also filter the sheet contents on the basis of some conditions. This can be made without much effort. It would be very much useful if we want to display only the rows that satisfy a particular condition. For example while declaring results of an exam if we want to display on the student‟s records whose mark is greater than 35, we can do this by using the filter options available in the spreadsheet. The following figure depicts the filtering example, where the rows with values 7000 are filtered. Fig 6.8: Filtering applied to the spreadsheet Charts Chart is one of the most useful tools available to portrait the complex data in more readable form. Spreadsheets have plenty of charting capabilities. We can produce multiple types of charts for the given data. The type of chart can also be modified instantly after making the chart. The following figures (figure 6.9 and figure 6.10) depicts various types of charts created using spreadsheet application. The data used for the chart is same as the data that is used in previous examples. The chart in the figure 6.9 is the bar chart where the names are plotted along the x axis and salary is plotted along y axis. The next one, figure 6.10 is the pie chart plotted for the same data. It should also be noted that we cannot simply draw any chart for any type of data. Certain type of charts requires data to be in a particular format. These things are to be noted while plotting chart using the spreadsheet applications.
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Fig 6.9: Bar chart created using spreadsheet application Fig 6.10: Pie chart using spreadsheet application 6.3.2 Desktop Publishing Tools (DTP) Desktop Publishing Tools are the tools which are used to create wide variety of documents which may range from a normal text document to an highly complex document consisting of many components other than text, like images, symbols etc., At this moment, you may have a question regarding the difference between word processing application and desktop publishing tool. In early days the word processing applications were built in keeping the document editing as primary feature than the document designing. But the recent word processing tools have almost many of the features available in a DTP tool. So nowadays features in both types of tools overlap each other. Functions The key function of a DTP tools is document layout and design. The power of a DTP tool depends on the features available in that tool which eases the design process of the document. As we have already stated these documents may have a rich mixture of text and other elements. So there should be easier ways to locate and format these elements in a document. There is an add-on complexity with images i.e., the source of an image may be from many sources. To be precise the text is normally entered only through a standard keyboard. But images can be imported from external sources or they scanned through scanner or created in the system itself using graphics manipulation tools. So DTP tools have the provisions to perform all these kinds of tasks.
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In the commercial environment a normal DTP operator will use more than one tool to perform the above mentioned operations. For example to manipulate images he/she can use a specific tool where as for creating integrated document another tool can be used. Almost all the present day DTP tools have the support to create the documents with multiple columns. This makes the process of the creating news magazines kind of documents, an easier one. Incorporation of Tables in to the document is also a standard facility available in a DTP tool. Screen Vs Printer In the beginning the target for DTP tools were only printers i.e., the final output is going to be distributed not only in a printed format. But nowadays we have many documents which are distributed in an electronic format. The document needs to be designed keeping in mind the final target i.e. printed form or electronic format. Because if the final format is electronic, then lot of additional features can be added like simple animations etc., which doesn‟t makes sense with printed format. Having said this we should also remember that, if we want to convert a document designed for electronic format to printed format, total work should not be repeated. So the format conversion features are also incorporated in to DTP tools. We also have Portable Document Format (PDF) which is widely used to distribute documents without affecting their layout and design. To view these documents there are certain tools like Acrobat Reader etc. These tools are available for all the major operating systems. PDF documents can be viewed exactly as they were created without any modifications in their format or layout.
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Tools To perform the above mentioned operations there are plenty of tools available in the industry. An enhanced survey of these tools is out of scope for this text. So what we have listed here is a sample collection of tools. The reader is encouraged to find out similar tools. To perform document layout and design, tools like PageMaker are used. To handle images, tools like CorelDraw or Photoshop comes handy. For animation related tasks tools like Flash are used. 6.3.3 Presentation Tools There are plenty of places where presentations are used like business project presentations, academic presentations etc. In the early days these presentations were done only through some special printed documents like OHP etc., But after the development of electronic presentation tools the scope of these presentations have become huge. Components Normally a presentation consists of number of slides. Each slide may consist of number of elements. There is a primary difference between a normal document and presentation. A good feature of a presentation is that we should not have clumsy text in the slide. Usually slides are prepared as bullet points. Presentation tools support animations also. The slide animations and the animations of components in the slide are also used to make the slide powerful. Tools There exist lots of presentation tools available in the industry. For example PowerPoint from Microsoft, Impress from OpenOffice etc.,
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All these tools have some basic features like slide insertion, Component insertion, Formatting, Adding animations etc. The features of these tools are very easy to understand. All these presentation tools have many of the features of word processing tools like fonts, coloring and themes etc. Covering all the features of a presentation tool itself is topic of a complete text. So here you would find the important features of a typical presentation tool. The screenshots shown in this section are taken with Microsoft PowerPoint tool. The following screenshot shows the startup screen of Microsoft PowerPoint tool. There you can notice three panes in the screen. The first pane shows you the thumbnail images of all the slides in the current presentation. The middle pane is the work area where you can actually place your contents. The last pane indicates various slide layout options. Using these options you can change the location and types of contents that you are going to place in your presentation. Figure 6.11: Initial Screen in PowerPoint Presentation Figure 6.12 : Procedure to insert a new Slide
Figure 6.13 : Slide Sorter View Figure 6.14 : Predefined Designs for Slides
PowerPoint gives you options to change the design of your slides easily. There exist many pre-defined designs which you can easily apply by clicking on them. Normally a presentation would contain more than one slide. The procedure to insert a new slide is to right click on the Left pane and select the
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“New Slide” option. This is shown in the screenshot. PowerPoint provides various views. One of the views that is mostly used is the slide sorter view. Using this Slide sorter view you can easily move around through your slides. You can easily change the ordering of slides by simply dragging the slides to whatever position you wish. This is shown in the screenshot The most important feature of any presentation tool is the ability to add animation to your slide. Animations enrich your slides. At the same time they are also used to catch the user‟s attention. Figure 6.15: Adding Animation to your slides Once you right-click on any object and select custom animation option, PowerPoint will provide you various pre-defined animations. It also provides good control over the animation that you apply i.e. you can control the animation speed, animation start time, start sequence etc. Figure 6.16: Applying animation to objects Apart from the presentation contents you can also have other contents like notes and handouts which are specifically useful for the presenter.
Figure 6.17 : Outline View in Presentation While printing PowerPoint provides various features like, number of slides to print in a page, whether to print slide contents or slide notes etc. This is shown in the following screenshot. Figure 6.18: Printer Options in presentation tools Figure 6.19: Grids for Proper Alignments
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If you want to design a professional quality presentation PowerPoint provides options to do that also. One of the important attribute of a good quality presentation is the alignment of contents. To align the contents accurately grids would help you. To display the grid you can select View:: Grid And Guides. Though the screenshots here are taken with MS PowerPoint, very similar options are available in all other presentation tools like OpenOffice, Star Office etc. Once you get an insight of any one these tools, it would very easy for you to get familiar with other tools. There exist many different versions of presentation tools exist i.e. in PowerPoint itself you have plenty of versions like 2000, XP, 2008, Mac Version etc. Normally there would be backward compatibility in these tools i.e. a presentation created with PowerPoint 2003 can be opened with 2008 but the vice-versa is not true. For example PowerPoint 2007 presentations would have an extension “pptx” which would not open in previous versions. But you can solve this problem by following any one of below given two ways:
While saving the presentation in 2007 version select the “Save As” option by saying compatible with previous versions i.e. you are now using 2007 but format you are saving would be off previous versions.
Using a “Viewer” in the target system where you would use your presentation. This method is little-bit difficult because of the fact that it requires the presence of viewer in target system which you cannot assure. So it would be better to go with the first option.
Normally all the presentation tools are designed by keeping the “Look And Feel” concept in mind i.e. you may not require an extensive training to work these presentation tools. If you have fundamental know-how of computers then you will feel very comfortable with presentation tools with very little training, if not nothing.
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6.4 Application Areas of Software It would be very difficult, if not impossible, to locate an area or field where software has got nothing to do. As of today you cannot find out any such area because software has become an omnipresent element. This section would provide you an insight in to the application areas of software. The application areas are being classified in to three sections. They are
Scientific Applications
Commercial Applications
Real Time Applications
Let us elaborate each area of applications in detail. 6.4.1 Scientific Applications of Software Scientific domain has been benefited by software hugely. Starting from basic sciences like Physics, Chemistry etc to applied scientific areas like aeronautics has got its own applications of software. In the scientific applications itself, you have lots of domains like medicine, engineering etc which have got revolutionized by software. The below list provides few application areas within the scientific domain:
Software Applications in Medicine
Software Applications in Engineering and Research
6.4.1.1 Software Applications in Medicine In the field of Medicine software is playing a vital role now. Initially software application in the field of medicine started with the computerization of patient database. Computerizing the patient database has got lots of advantages:
Easy retrieval of Patient Data: In a hospital where the number of patients is large it would be very difficult to retrieve the data of a patient if it is maintained using the traditional ledgers. But if the patient data is computerized it can be easily retrieved with the help of software.
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Complete view of Patient History Data: By applying software in patient history maintenance it would be easy to get the complete picture of patient history information. For example consider a scenario where a hospital has got various branches across the country and if all the branches are networked then retrieving the treatment details of a patient at any branch of the hospital becomes very easy. Apart from this patient data maintenance software has got many roles to
play in the field of Medicine. One such application is the CT Scan or (Computer Tomography) which is used to scan the internal organs of the human body. This CT scan facility has made the diagnosis of many of the problems easier and effective. Another application which is catching up in medicine is the idea of “Telemedicine”. Telemedicine makes the communication between patient and a physician much easier and simpler. Inaccessibility due to geographical distances has now been removed. A patient can communicate with the physician anywhere in the world through the help of telemedicine. The biggest advantage of this technology is that the rural areas will get much benefit. In a country like ours where majority of the population still lives in the villages it becomes ultimately necessary to provide those people the latest technologies. Another related field is called “Tele-radiology” where the digitized images of X-Rays would be transmitted over wire or air to reach the expert physician anywhere in the world. All the “surgical monitoring equipments” are now computerized. If you look at any surgery you would find equipment which keeps on reading the heart beat, another for reading the blood pressure etc. All these equipments are controlled through the help of software. The advantage of this process is the accuracy of information and control. If something goes wrong during the surgical process the surgeon would get accurate alert messages with the help of these software controlled equipments. Robot controlled surgical process is also another important software application in the field of medicine.
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There exist other cutting-edge software technologies which has given new dimensions to the diagnosis and treatment procedure. For example researchers have developed various implantable chips. With the help of these implantable chips the physician would get the real time data about the happenings of patient body. With the help of these data doctors can take actions as early as possible. With the help of internet and World Wide Web now the patients have access to state-of-art developments in the field of medicine. The benefit of this is the better understanding about the diseases. It has also improved the coordination between the doctor and the patient. Another interesting field of study is bio-informatics. Application of information technology to biology is called bio-informatics. Application to biology implies the application to medicine. The speed with which the process can be completed is totally been improved by the software application. The above discussion is an outline about the applications of software in the field of medicine. To summarize the major benefits are listed below:
Efficient Maintenance of patient data with software
Telemedicine and Tele-radiology
Surgical monitoring equipments
Software controlled implantable chips
Accessibility to state-of-art developments in medicine through WWW
Bio-Informatics advancements
6.4.1.2 Software Applications in Engineering and Research Engineering is another field where software has introduced remarkable changes. To name a few:
Computer Aided Designing (CAD): Software has improved the quality and speed of the designing process. Design processes are normally iterative in nature. Manual iterations are tough to do because every time
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you have to start from the scratch where as software application has drastically reduced the time taken for this process. There exist many CAD tools available today in the market. To name a few: OpenCAD, AutoCAD from Autodesk etc.
Geographical Information Systems (GIS): GIS are very much helpful for navigation purposes. GIS in mobile phones has totally modified the approach towards travel to a new place. In GIS satellite controlled information would be provided to the user so that he/she would get a complete picture about the particular geographical location.
Simulation Process: Certain experiments would be costlier in nature which you cannot repeatedly carryout because of various restrictions. These experiments can be carried out through the help of simulation process. If something goes wrong you can identify it during the simulation process itself. For example, a car can be tested for various conditions with the help of simulation process before the actual manufacturing starts. If some shortcomings are found they can be corrected during this simulation stage itself. If no simulation is carried out then the actual problem would be observed after the manufacturing process which would be costly to correct.
Collaboratory: Collaboratory stands for Collaborative + Laboratory. This is among the recent trend which is getting the attraction from scientists all across the globe. The basic idea of Collaboratory is as follows: It is an internet enabled laboratory which the scientist from various registered institutions can access. By which the findings of various scientist can be shared by which the quality and speed of research would be increased.
Industrial Process Control: Processing controlling in the industry is widely improved by software application. Any industrial process would have a workflow. This workflow may be controlled with the help of the
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software applications. Another dimension of industrial process control is the quality assurance or (QA). This QA plays a vital role in deciding the final products quality. The QA can be guaranteed for improved accuracy through the help of software applications.
Astronomical applications: Software applications in astronomy are also huge. The field of astronomy is full of complex mathematical calculations. If these calculations have to be carried out manually you cannot guarantee the accuracy of final output. Apart from the accuracy factor, time delay is also a critical criterion. All these calculations are now computerized and automated. This makes the human-time available for other complicated tasks rather wasting in to these repetitive mathematical calculations.
Others:
Apart from the above specified applications there exist
applications of software in many other fields. The software applications in the archaeological research are also phenomenal. In the field of chemistry the software applications include “chemical reaction simulation” etc. Taxonomy based approach is followed in many fields like biology, chemistry etc. In all these fields the taxonomy management is effectively carried out with the help of software.
6.4.2 Commercial Applications Software has got equal impact in commercial applications also. This section would list out various important commercial applications of software:
Banking Technology: Banking is one of the areas where software is playing a role from a lengthier period of time. Banking usually includes many routine processes. These routine processes have to be carried out with greater accuracy. Software has provided the platform to perform all these tasks effectively as well as accurately. Another important factor to note down in this domain is the “Security”. All the banking transaction
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data to be secure in nature i.e. only the authorized people should access these data. Software has provided solutions to this security problems aswell. The popular usage of ATM all across the globe is the gift of Information Technology to the humanity.
Sales and Marketing: Sales and marketing are the two areas where the right information at right time to right people can directly be translated in to money. Sales and marketing usually includes huge data. Finding the patterns across these data is a challenging task. There is a detailed study in the computer science field which is called “Data Mining and Warehousing”. Roughly this data mining and warehousing is application of software to a huge collection of data to find out some patterns across these data. Once you find out these patterns they can be effectively used to promote the sales and marketing.
E-Commerce: E-commerce has a phenomenal impact on the way in which we buy and sell products. With the help of e-commerce you can purchase products on-line i.e. through internet and World Wide Web. Ecommerce has modified the retailing industry to a greater extent. In ECommerce also security becomes a critical thing to monitor. Now we have various security mechanisms that can be applied with the help of software.
Stocks: Stocks trading is now performed largely with the help of internet and World Wide Web. This facilitates the quick transactions and recent information.
6.4.3 Real Time Applications A real time application requires the output to be delivered within the specified time limit. The output after the specified time limit would have very less impact if not nothing. The following are examples real time applications.
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Air traffic control: Air traffic control is a time sensitive application. The software has to provide the information within the exact time boundary. If the information is not delivered within the specified boundary it can result chaotic sequences of events.
Surgery monitoring tools: As indicated previously in the applications of software in the medicine section, there exist many software controlled equipments for monitoring the surgical process. These tools have to provide results in real time. If they don‟t provide the results with in the time limit they would become unusable because a tool which gives you the warning after the actual problem would be not usable. These are all the various applications of software in domains like
scientific, commercial and real time application. Summary
Programming language is a tool for providing instructions to the computer.
There exist five generations of programming lanuguages. Each generation of language has got improvement over previous generation.
First generation language was very close the computer. They were hard to understand for the humans.
Second generation language used the nemonic codes. They would be translated by a special tool called assembler.
Third generation languages are portable. The program written in one machine can be easily ported to other machines.
Fourth generation languages don't require the “how to do”. They require only the “what to do”.
Fifth generation languages are primarily associated with artificial intelligence and related concepts.
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Packages are predefined tools which can be used to perform some useful tasks. Packages don‟t require programming knowledge.
Spreadsheet is a type of package which is used to perform mathematical calculations.
Desktop publishing includes tools for designing. DTP tools are used in the printing industry prominently.
Presentation tools enable the user to compile number of slides in to one presentation. User can add animation and sound effects to these slides.
There exist various applications areas of software. For example scientific
application,
commercial
applications
and
real
time
applications.
Scientific application includes the application of software in medical field and various engineering and research applications.
Commercial applications of software are in to various fields like banking domains, e-commerce etc.
Real time applications have to follow the deadline factor. For example software controlling the movements of a vehicle has to strictly adhere the time boundary.
Self Assessment Questions Part I (Multiple Choice Questions)
Assemblers were used in
First generation language
Second generation language
Third generation language
All of the above
None of the above
Visual basic is primarily used for
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System programming
Internet programming
Rapid Application development
All of the above
None of the above
Which of the following language(s) is/are compiler based language
C
Java
COBOL
All of the above
None of the above
Packages are
Predefined tools
Well tested
Doesn't require programming knowledge
All of the above
None of the above
The spreadsheet is madeup of
pages
cells
lines
All of the above
None of the above
Desktop publishing involves tools like
Pagemaker
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Coreldraw
Photoshop
All of the above
None of the above
CAD stands for
Computer Aided Designing
Computer Application Domain
Computer Aided Data
All of the above
None of the above
Which of the following is an example for real time application
air traffic control
surgery monitoring tools
fuel control systems
All of the above
None of the above
A Presentation is generally made up of
Cells
Slides
Documents
All of the above
None of the above
Which of the following is/are tool(s) used with programming languages
Assembler
Compiler
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Interpreter
All of the above
None of the above
Part II (Short Questions) 11.
Define the term “programming language”.
Write short notes on “Assembler”.
Explain the advantages of third generation languages.
Write short notes on spreadsheet applications.
List out various application areas of software.
Write short notes on real time applications.
Write short notes on presentation tools. Part III (Long Answer Questions)
Explain in detail about various generations of programming lanuguages.
Explain in details about spreadsheet and presentation tools.
Elaborate on various application areas of software.
Answer Key 1. b
2. c
3. d
4. d
5. b
6. d
7. a
8. d
9. b
10. d Part II
Programming languages are tools for communication with computer. They are used to provide instructions to the computer. There exist five generations of programming languages.
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Assembler is a translator used with Assembly Language Programming. It is used to convert assembly language program in to machine language.
Third generation languages are called high level languages. The program written in third generation languages is portable in nature. They are more readable also.
Spreadsheet applications are generally used with applications involving numeric calculations. There exist many spreadsheet tools. For example Microsoft Excel.
There exist various application areas of software. They include scientific applications, commercial applications and real time applications.
Applications where time is the critical factor are called real-time applications. There exist two types of real-time applications. They are soft real-time and hard-real time applications.
Presentation tools are helpful to convey concepts. They are used for demonstrations purposes also. There exist many presentation tools exists. One of the popular examples is Microsoft PowerPoint. There exist opensource presentation tools also. One of the examples is the presentation tools used with OpenOffice.
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Lesson 7: Introduction to Internet Introduction
Internet is the largest network. Internet is global scale network.
Internet can be called as network of networks or Global Area Network.
Internet has totally modified the way people communicate and share information to a greater extent.
After the advent of internet, world has become global village.
Internet has made communication easier and effective.
This lesson would elaborate on various aspects of internet.
Objectives 1. Providing the brief history of internet 2. Explaining the internet communication methodology 3. Providing information about Internet Service Providers 4. Explaining the concept of IP addresses 5. Discussing about the functionalities of Domain Name Systems 6. Introducing various web browsers and explaining their merits and demerits 7. Elaborating about the e-mails 8. Discussing about the file transfer protocols 9. Outlining the purpose of HTML and introducing simple tags in HTML. 10.
Providing information about BBS
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7.1 The Birth of Internet The traditional networks like LAN, MAN etc were easily breakable i.e. you can make the network inefficient by breaking very less number of connections if not one. There was need for a network which can not be broken easily i.e. you can not isolate a computer from such a network by simply breaking one connection. The result was internet. It all began with ARPANET (Advanced Research Project Agency Network) in USA. The primary purpose of ARPANET was to provide a network which is stronger in terms of connectivity. ARPANET was established during late 1960s. Initially ARPANET was connecting only four locations. ARPANET was primarily for defense purposes. Following this NSF (National Science Foundation) created a network called CSnet. The purpose of CSnet was to link universities (especially researchers in the field of computer science) in US. This happened during 1980s. Following this a very fast internet backbone was created. Organizations linked to this backbone to establish connection to internet. Up to this point internet was primarily viewed as a communication medium for research. In the mid 90‟s internet became the network of general public. Following this a new way of business flourished called e-commerce which leads to the fascinating growth of internet. This is how internet came into existence. Today we all use internet for variety of purposes. Various applications of internet are discussed in detail in later portions of this text.
7.2 Internet Communication Methodology Internet primarily uses the public telecommunication lines for its connection establishment. The telephone lines are primarily used to transfer voice signals. Computers work on the basis of digital signals. In order to use the
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public telecommunication system the digital data has to be converted in to analog data and vice-versa. There is a device for doing this called Modem. The purpose modem is modulation + demodulation. Conversion of digital signals to analog and vice-versa is the role of modem. This is illustrated in the Figure 7.1. Figure 7.1: Modem connecting computers and Telephone networks
There are various ways of connecting to internet. Most popular among them are listed below:
Dial-up Connection: For dial-up you would be using your telephone in your home for dialing a particular number to contact the Internet Service Provider. Dial-up connections are slow in nature. Their speed of communication would be very few kbps (kilo bits per second, 4 kbps refers 4000 bits per second)
Broad band connection: Broad band connections are faster. They are faster than dial-up by many folds. You can use broad band connection if your internet access involves multiple media of data. The speed of broadband connection would be in terms of Mbps (Mega bits per second, for example eight Mbps refers to eight million bits per second) Apart from these two there are other techniques like ISDN (Integrated
Services Digital Network), Satellite way of communication etc. But only the dial-up and broad band are used in a massive scale for connecting to internet.
7.3 Internet Service Providers Internet Service Providers or simply ISPs are the organization from which you get internet connection. The above mentioned ways of connecting to internet has to be provided by these ISPs.
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In our country there exist many Internet Service Providers. For example BSNL (Bharath Sanchar Nigam Limited) is public sector ISP providing internet connectivity all across the country. Each ISP would provide various different packages for internet connectivity just like your telephone connections. You can choose one according to your needs and usage. The billing for internet would be generally on the basis of time in case of dial-up connections. And in the case of broadband the amount of data transferred would be taken into consideration for billing. In case of dial-up apart from the internet time charges you may also required to pay the billing for telephone separately. Nowadays ISPs are providing attractive plans like pay a constant amount and use unlimited internet. Again the choice of particular scheme selection and for that matter ISP selection also purely depends on your usage. Apart from wired internet connectivity nowadays ISPs provide wireless internet also. To access wireless internet, ISPs provide a device which you can attach to your USB port. By using this device you can easily access internet on the move. The local access point that ISPs provide for you is called POP or Point of Presence. The connection from your system would first lead to this POP. Then from this POP, Network Access Points (NAP) are used to further travel through the network. Nowadays many ISP‟s networks are not copper wire networks. They are all optical-fiber networks. By using optical-fiber the speed of connectivity again increases and also the loss of data is reduced.
7.4 Internet = World Wide Web? Many of you may be having an opinion that internet and WWW are the same. Are they really same? The surprising answer for this question is “NO”. Internet and World Wide Web are not the same.
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Then you may ask the question that what is the difference between internet and World Wide Web? The answer for this question is as follows: Internet is actually the underlying network and World Wide Web is one of the services running on internet. What does this actually means? Internet refers to the physical network. On top this physical network many services are running like e-mail, ftp (file transfer protocol) etc. World Wide Web is simply another service running on internet. Since World Wide Web is used in massive scale many people interchangeably use the terms World Wide Web and Internet. Ideally speaking they cannot be interchanged for one another.
7.5 IP Address The World Wide Web primarily uses two protocols. They are Transmission Control Protocol (TCP) and Internet Protocol (IP). These two protocols make the WWW access easier and efficient. IP address refers to Internet Protocol Address. Any computer linked to the internet has an IP address. A typical IP address would have four components or four octets. For example it would look like 172.16.0.25. There are two types of IP address assigning. They are
Dynamic IP address: This type of IP addresses would change every time you connect to the internet. So they are called dynamic. For example if you are using a dial-up connection for accessing internet, every time you connect to the internet you would be given an IP address. This IP address is only for that session. If you connect at a later point you can notice that the IP address has changed.
Static IP address: As the name indicate static IP addresses doesn‟t change frequently. As your computer is having an IP address so is server computer. If the IP address of the server is changing for every connection that it would
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become impossible to locate a web server. (Web servers hold the web pages in them. A single web server can host multiple web pages). At this point in time you may have a question in your mind that how to identify the IP address. There is a simple way to do this. If you are using Windows operating system go to the command prompt and execute the command “ipconfig”. The result would give the IP details of your computer. If you are using a Linux based machine then go to the terminal and type the command “ifconfig” and press enter. It will give you the IP address details. (In Linux there are certain permission issues to execute this “ifconfig” command). This IP addresses are not only used in internet connectivity but they can be used with in your organization network also. If your organization is having hundred computers networked together then you can identify each single computer by using the IP address. More over you can organize computer into different groups by providing a particular range of IP address. For doing this concepts like subnet masks are used.
7.6 Internet Naming and Addressing Now you have learned that each computer connected to the internet is having a unique IP address. So you can access a particular machine provided that you know the IP address. But there is a problem with this kind of approach. The problem is the number of computers connected to the internet is in terms of billions. So it would not be possible for a normal human being to remember specific IP addresses for specific machines or server. The solution to this problem is to use names instead of numbers because human brain is comfortable in remembering names than the numbers. So you can easily access a specific web site by typing the name (called URL – Uniform Resource Locator)
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7.6.1 Domain Name Systems As specified above you would be using URL for accessing a particular web site. So there is a need for a translator which would translate the human readable URLs into IP addresses. These systems are called Domain Name Systems or DNS. The role of DNS is as depicted below: Figure 7.2: DNS between URL and IP address At first sight you may be feel that the role of DNS is very simple but it is not so. DNS is the invisible part of internet to the end-user. If the DNS shut downs for a fraction of time then the total World Wide Web would become unusable because no one remembers the IP address. The factors that make the DNS critical and complicated are as listed below:
The number of IP addresses is very huge. So DNS conversion can not happen at a single machine for the whole World Wide Web. This makes the DNS distributed. Actually DNS is the largest distributed database.
There are millions of changes happening each day. So the DNS has to accommodate all these changes.
The DNS has to perform this conversion in real time i.e. the conversion should happen within the specified time limit. (In fact DNS is a good example for soft real time system which is explained previously in this text)
7.6.2 Components of a URL A typical URL has various components. For example consider the following URL: http://www.pondiuni.edu.in/departments/computerscience.php Where http://www
- Protocol
pondiuni.edu.in
- Domain Name
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departments
- Internal Directory in the domain
computerscience.php
- actual web page
So when you type the above mentioned URL in a browser following list of events happens
Convert the domain name into IP address by using DNS
Locate that IP address (By using routers)
Locate the directory “departments” within that server
Fetch the page “computerscience.php”
Send the page to your computer to render it in your browser. The above sequence is not only applied for this URL but this is the generic
procedure which is applied for any URL. 7.6.3 Domain Types There exist different types of domains. Domain classification is done on the basis of type of content that particular web site holds. If your recall the previous example there “pondiuni.edu.in” was mentioned as domain name. This domain itself can contain many components. In this particular domain name you can find three components. They are
pondiuni
- Refers to the organization‟s name (Pondicherry University)
edu
- Refers to the type of organization (Educational)
in
- Refers to the country (India)
All the countries are assigned a two letter short form to make it easy to include in the URL. For example (“in” for India, “sg” for Singapore etc) Generally there are certain top level domains. They are as listed below:
.com
- Commercial Purpose
.mil
- Military purpose
.org
- Non profit organization
.gov
- Government
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.net
- Network
.edu
- educational
Immediately by looking at a URL you can find out the location (country) of the organization and purpose of the organization. In a particular domain no two URLs can be same. But if the top level domain changes then you can have the same name. For example it is valid to have the following two URLs:
www.pondiuni.org
www.pondiuni.edu.in These URLs are valid because the top level domain in first URL is “org”
whereas in second URL it is “edu.in”. You may notice that in the first URL no country name component present. It is not mandatory to have the country name component. But if the URL includes country name component then you can easily identify the location. Two URLs can differ in country name component also. For example:
www.google.co.in
www.google.co.fr
The above two URLs are valid because they differ in the country name component. Another point that you would have noted is that here the protocol name “http” is not used. Most of the time even you miss the http:// you would be able to access that web site.
7.6.4 Secure URLs If a particular site is providing facilities involving financial transactions then there is need for security. To facilitate such security there is a variation to http protocol. (http is hyper text transfer protocol)
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The secure variation of http is called “https”. “https” stands for Hyper Text Transfer Protocol Secure. You could have noticed the presence of https in sites providing facilities like net banking etc. If you enter a URL which is using https protocol then your browser itself indicates this by changing the address bar background to yellowish color. (This happens in browsers like Mozilla Firefox) “https” is not only for financial transaction sites but it can be used for any URL that need to be secure. For example the mail service provided by Google i.e GMail normally uses the https version. This indicates that the particular page is more secure and you can rely on that service.
7.7 Browsers The tools that enable you to access World Wide Web are the browsers. Today you have lot of options to choose the browser of your interest. This section would describe about various popular browsers and their specialty and drawbacks. A web browser can be defined as follows: “Web browser is software that enables you to access the World Wide Web” Browsers have the following attributes:
All the web browsers primarily use the HTTP (Hyper Text Transfer Protocol)
Web browsers have the capability to handle multiple forms of data like text, images, audio, video etc.
Browsers would be able to identify any page by means of URL
7.7.1 Popularly used Browsers The list of all web browsers available today is very long. We will not be presenting all those browsers. This section gives you a list of browsers which are commonly used by the general public. They are as follows:
Internet Explorer
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Mozilla Firefox
Opera
Safari
Netscape Navigator
Chrome (The elements in the above list are not sorted in terms of their popularity) Let us look in detail about each of the above browsers in the above list
both in terms of advantages and short-comings. 7.7.2 Rendering Engines Before studying the browsers it becomes necessary that you should get an insight about an underlying concept regarding web browsers. They are “rendering engines”. A rendering engine is the core component of any web browser that takes care of how to display or render the pages. So it is the rendering engine which actually defines the behavior of web browsers to a greater extent. Popularly used rendering engines are:
Trident
Gecko
Webkit
Presto etc A deeper study of these rendering engines would be out of scope of our
current text. 7.7.3 Internet Explorer Internet explorer is the default web browser in Microsoft Windows operating systems. Details about IE are listed below:
Internet Explorer is developed by Microsoft
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Internet Explorer is made available as a part of OS with Windows (95 or later)
IE supports tabbed browsing
Zone based security is possible with IE
Complete support for COM (Component Object Model) is there in IE
Internet Explorer uses the Trident Rendering Engine
Major criticism of IE is regarding its security.
7.7.4 Mozilla Firefox Firefox is certainly a forerunner in terms of browser usage apart from Internet Explorer. Firefox has got its wide acceptance among the developer community if not everybody. The facts about Firefox are as below:
Firefox is developed by Mozilla
First version of Firefox is released during November 2004.
Firefox is a cross platform Web browser. Firefox versions are available for all the major operating systems.
Firefox is based on Gecko Rendering engine
Source code of Firefox is available
Supports tabbed browsing
Provision for Incremental search is there.
One of the major advantages of Firefox is the ability to extend. There exist many Firefox extensions available. Recently there is huge interest in developing extensions for Firefox among the developer community all over.
Integrated Download manager is an added feature of Firefox. By using this you can easily manage your downloads.
Major criticism about Firefox is the delay in loading the browser. It takes few seconds to make the browser up. It also takes up a considerable amount of memory.
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7.7.5 Safari Safari is the default browser with Macintosh operating system (i.e. Apple computers). Facts about Safari are as listed below:
Safari Browser is a product of Apple.
First version of Safari was released during 2003.
Safari uses the Webkit rendering engine
Complete support for CSS (Cascaded Style Sheets) is the important feature of Safari browser.
Safari browser loads the pages comparatively faster by using various techniques.
Tabbed browsing is also supported in Safari
Elegant User Interface of Safari makes your browser session smoother.
Safari supports RSS (Really Simple Syndication)
7.7.6 Opera Opera is another popularly used browser among the web users. Facts about Opera are as listed below:
Opera is a cross platform Web browser. (Versions exist for all the major operating systems)
Opera versions exist for mobile phones and PDA. Miniature version of Opera is called Opera – Mini.
Opera is based on Presto rendering engine.
Thumbnail preview of pages are provided in Opera.
Opera supports various Widgets (Utility tools)
Opera also supports mouse gestures i.e. apart from click, double click, drag you can perform events by moving your mouse in a specified patterns.
Content blocker facility is there in Opera
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7.7.7 Netscape Navigator Netscape has played a critical role in making the browsers popular among the web users during the early stages of World Wide Web. The facts about Netscape Navigator are as listed below;
Navigator was released during 1994 (as beta version).
Netscape Navigator versions are available for Windows, Mac etc.
Criticism about Netscape Navigator is the poor support for CSS and XML. (Many of the above specified browsers have got a good support in handling XML).
7.7.8 Google Chrome Chrome is the recent addition to the browser family. The facts about chrome are as listed below:
Chrome is a product of Google.
Chrome is still in Beta release ( As of November 2008)
Chrome is based on Webkit rendering engine (same engine is used with safari also).
Chrome supports tabbed browsing. Here the advantage is that each tab would be considered as a separate process so problem in one tab would not affect others.
Chrome has introduced a new JavaScript handler called “V8”.
Chrome has many developer friendly features like JavaScript debugging, elements inspection etc.
Since Chrome is still in beta few of the web pages seems to be rendered in chrome with broken manner. There is a good chance that these errors would be rectified in the complete release.
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7.7.9 So, which is the best browser? After reading all the facts about various browsers, now you may have a question in your mind that which is the best web browser. There is no single answer is there for this question. The choice of browser can be made on the basis of following factors:
The hardware that you use is an important factor. For example if you are using a mobile phone or PDA then Opera is a good choice.
The platform in which you work also has the major role to play in browser selection. For example Safari being the default browser in Mac OS (Of course here you can go for other browsers also but the default browser would have been tailor made for that particular Operating System).
The type of content or type of web application that you use is also a factor in selecting an ideal browser for your purpose. Since browser is the interface through which you are accessing the
World Wide Web, a proper browser should be selected for your purpose based on the above listed factors.
7.8 Electronic Mail Electronic Mail or simply e-mail has become the commonest way of communication. E-mail has certain distinct advantages comparing other ways of communication as listed below:
E-mail communication is much faster than traditional communication methods
E-mail is a global scale communication technology. (e-mail doesn‟t insists any geographical boundaries)
Apart from text other media of data like image, audio etc can be attached with e-mail.
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7.8.1 E-mail requirements To use e-mail you need certain requirements. These requirements are as listed below:
Internet connectivity
An e-mail account
An e-mail client. (e-mail client is optional because there exist many web based interfaces for e-mail like Gmail or Yahoo etc). There are many popular e-mail clients like Mozilla Thunderbird, Microsoft
Outlook express etc. Some of them are open source and others are proprietary. Similar to web browser, selection of e-mail client selection should also be done with great care by taking your hardware and usage into consideration. 7.8.2 E-mail Services Nowadays you have plenty of choices in selecting the e-mail services. Many free services also exist. Popular among the e-mail services are as listed below:
Gmail
Yahoo mail
hotmail
rediffmail etc All the above specified e-mail services are free. You can create an
account with them freely. Some of the e-mail services provide multiple types services like free services and the premium services. 7.8.3 Your e-mail address A typical e-mail address has the following format: user_id@provider_domain For example
[email protected]
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Where Pucsc
-
User
Id
(Pondicherry
University Computer Science) gmail
- The e-mail service provider name. The '@' symbol is used to separate the user_id and provider domain. The
user_id with in any single domain should be unique. Some of the e-mail addresses also include the country specification as part of their domain. For example
[email protected] Here “in” indicate the country India. Apart from these general e-mail service providers many organizations has their own specific e-mail service. For example Pondicherry University e-mail id's would like as given below:
[email protected] For example:
[email protected] Where csc
- Computer Science
pondiuni
- Pondicherry University
edu
- Educational institutions
in
- denotes the country India. These organization specific e-mails are primarily uesd for official
communication purposes. 7.8.4 An e-mail account for you To proceed with e-mail first of all you should have an e-mail address. This section would elaborate on the process of creation of an e-mail account. The procedure is as listed below:
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By typing the e-mail service providers address in to a browser you can land on the home page of that e-mail service. For example mail.google.com is the address for launching the Google Mail (Gmail)
At this point there are two choices. If you have an e-mail address you can enter there and login. If you don't have the e-mail id click on the “sign up now” or similar option.
This would lead you to a page where you have to enter certain data. First of them would be your e-mail id.
After entering your e-mail id it would be checked for duplicates. If no such id exists it would be allowed otherwise you would be asked to enter a different user-id. This check is made because an e-mail id is unique i.e. No two user would be given the same id.
Apart from the user-id it would ask details like your name, contact address, other e-mails (if you have any) and your preferences etc.
After entering all these information you can submit the form to create an email account for you. Other than this mode of creation there exists other ways also. For
example if you are working in an organization then the organization itself may provide you an e-mail id. One more method of getting e-mail id is from the ISPs (Internet Service Providers) itself. Some of the ISPs would provide you an e-mail address when you purchase an internet account from them. 7.8.5 How to send an e-mail? Let us assume that you are using web based e-mail. You have to follow the steps given below to send an e-mail:
Login into the e-mail site. While creating an e-mail account they would ask for an e-mail id and password. By typing this e-mail id and password you can log-in into your e-mail account.
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After login by default most of the e-mail services would display your inbox where you can find your incoming mails.
To send an e-mail click on the “compose” option.
After clicking compose option you would get a screen where you have to enter the “to address”. This indicates the user to whom you wish to send the e-mail.
Apart from “to address” you can also enter “cc”. It indicates the carbon copy. Same mail would be sent to these users also.
One more type of address that you can enter is called “bcc”. It denotes “blind carbon copy”. The mail would be sent to these recipients also without the knowledge of other recipients.
In the above specified addresses it is not mandatory to enter all of them. All other addresses are optional.
After entering these addresses you have to enter the actual message body in the message area.
Once you have entered the message then click on the “send” option to send the message.
If the message is successfully sent then you would be given a message similar to “Your e-mail sent” etc. If the message is failed because of address error or any other error you would receive an e-mail from the provider indicating the failure of message. In such cases you can check the e-mail address for proper spelling. Apart from the above specified steps there is another option called
“attachments”. Attachments are very much useful in case you want to send some additional files along with your e-mail. In such a case you can choose the file that is to be sent as attachment before clicking the “send” button. While selecting the attachments you have to consider the following facts.
The size of the file should not be big. Optimal size is in terms of KB or one or two MB.
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The files that you attach would be scanned for virus. In cases where your file is infected with virus many providers deny the attachments.
The number of attachments can be more than one also. In case where you are sending a big file it is better that you can split that file into two to three pieces and then send them as individual attachment. This becomes helpful in scenarios where the internet speeds in very less. A big file can fail to upload or download. In such cases these small files can help you. Most of the viruses send with e-mail are sent as attachments. So it is a
good practice that not to open the attachments from unidentified sources. 7.8.6 Security with e-mail One of the major problems among the e-mail users today is the security. There is a category of e-mail called spam mail. These mails are product of malicious users. service. These mails are unsolicited in nature. These mails would greatly disturb in accessing your regular mails. At times these mails can have viruses also. Your computer would get affected by these viruses if you simply view or download these mails. The question that you can ask now is “how can I protect my system from these viruses?” It can be done if you follow the below given steps:
Never open an e-mail which you believe as a spam. Otherwise if you have got an e-mail from unidentified sources never open them. Simply delete those mails without carrying out any further action.
You can also use spam filter options provided by many email services. For that matter many e-mail services provide free spam filters. For example “Spaminator”.
Once you identify an email as spams do not reply to that mail. By replying to the spam mail you are actually increasing the possibility of further attacks. Because now the spam sender has got the information that your e-mail is active.
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Apart from the above mentioned step you can also take a precautionary action. Never enter your email id in forms where you feel the authenticity of the site is not genuine. Because from these sites all the collected e-mails may be provided to persons or organizations who/which are sending the spam.
You have to think twice before entering your e-mail password in any other site. Because by providing both your Id and password you are giving the complete control of your e-mail account to a third person which may lead to critical problems.
7.8.7 Other e-mail Services Apart from providing the facility to send and receive e-mail many providers provides additional services like Instant Messaging. This instant messaging service is simply called IM. IM allows you to chat in real time. There exist many popular IM services. Few of them are as listed below:
Gmail Chat (A chat option available within your mail page itself)
Yahoo Messenger
MSN Messenger
AOL Messenger Many of the messengers provide you a client side tool which you can
download to your system. Then you can install and configure with your e-mail id according to your need. You can use this chat facility when the person with whom you want to chat is also online. All the e-mail services have the facility of address book. In this address book you can store the e-mail details about persons with whom you have regular contact. The primary advantage of this address book is that you don't need to remember the e-mail address. Another advantage is that it helps to avoid spell mistakes i.e., when you type the e-mail address yourself there is a possibility of
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typing it with spell mistakes. But when you select from address book where it is stored correctly there is no possibility of spell mistakes. Another point in organizing your e-mails is to properly store them in folders. Instead of keeping all the mails in the Inbox you can create many folders according to your choice and move the mails to corresponding folders. Apart from Individual e-mails there exits group mails also which are primarily used to share information among people with a common interest. There exist many such popular e-mail discussion groups are available in internet.
7.9 File Transfer Transferring files from one location to another in a network is a common phenomenon. To accomplish this file transfer there is a protocol called File transfer protocol or simply FTP. Facts about FTP are as listed below:
FTP is an open standard protocol i.e., it is not proprietary in nature
FTP by default uses the port number 21.
FTP can be used to transfer files in networks which support TCP/IP
FTP is not restricted to any single Operating system.
FTP removes the file systems barriers i.e., the user need not worry about the kind of file system that the server is using. To establish connections in FTP you need two programs. They are called
FTP client and FTP server. FTP client program would communicate the FTP server program to perform operations like reading the file content, writing, renaming etc. There are three modes of in FTP. They are active mode, passive mode, extended passive mode. Each mode has got its own method of operation. FTP can be used in cases where ever there is a need to transfer files from one location to another. It is been widely used to share some content over
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internet. You share files through e-mail as attachments but there is a restriction to that, in terms of file size. If the size of the file to be transferred is high then FTP can be used instead of e-mails. FTP allows to you to transfer files of bigger sizes also over internet. There are many FTP client programs available today. Few of them are also available freely. Most of the browsers do have the facility to support FTP. While accessing FTP sites the protocol ftp or ftps (FTP over SSL) should be used instead of http. For example an ftp URL may look like ftp://pucsc/it.pdf. FTP access can be either based on a user name, password mode or it can be also be in anonymous mode. In the case of anonymous mode there is no need for providing the username and password. This anonymous mode is used in sites where contents can be downloaded by anyone who visits that FTP site. 7.9.1 FTP data transfer FTP data transfer can happen in two modes. They are ASCII (American Standard Code for Information Interchange) and Binary format. ASCII would be used while transferring plain text. Here the character by character ASCII would be transferred over the network and the receiving computer would covert it back to character. ASCII mode would be helpful only for text based data transfer. When the data to be transferred is in the form of non-text like images, other file formats etc, the binary mode would be used. Here the bit stream wise data transfer would take place. If ASCII mode or text mode is used for above mentioned usage then it has the possibility to corrupt the files that are transferred. 7.9.2 FTP demerits Though FTP helps to transfer files from one location to another it do have certain problems. They are as listed below:
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FTP protocol doesn‟t follow any encryption techniques. So it becomes relatively insecure to transfer data through FTP.
The latency (delay) associated with FTP is high.
FTP doesn't checks for the correctness of data. Many data transfer methods follow the error checking procedure where as in FTP there is no error checking is available.
FTP data can be easily sniffed by other in the same network. There is a version of FTP which is called FTPS (FTP over SSL; SSL
stands for Secure Socket Layer) which is more secure than the FTP. Though FTP has got above mentioned problems, it is still a widely used protocol to transfer files over internet. Many popular sites provide FTP support, if there is a need for transferring files from the users or to the user.
7.10 Bulletin Board System (BBS) Bulletin Board System or simply BBS were very popular during 1980s. Their popularity diminished after the massive growth of World Wide Web. This section would provide details about Bulletin Board Systems. Bulletin Board Systems are primarily used to share data. You can connect to a BBS by dialing up a specific number. Once the connection is established you can download data or even software from BBS. Some of BBS were free i.e., there is no need to pay anything to them for using their service. But there were other kind of BBS where you have to pay them money for accessing their services. Primarily data that was exchanged through BBS were images etc. Apart from images there were textual data like articles. BBS can be considered as ancestors of today‟s social networking sites. (Though today, social networking sites provide far better facilities than the BBS of olden days).
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One of the popular BBS used during those times was called FidoNet. FidoNet was very popular based on the type of services it provided. There were many other BBS which were very similar to FidoNet (in fact they all used the same software and techniques that were used with FidoNet). All those networks were called FidoNet Technology Network (FTNs). BBS were unreliable in nature because they were not operated from a high quality server centre or similar. Many users hosted BBS in their own machines. So connectivity was not that much reliable. BBS acted as discussion forums as well where users with a specific interest can share their views by posting information on these BBS.
7.11 Introduction to Intranet and Extranet The standards and protocols that are used with internet are well-defined. So there was a thought among IT people why these techniques should not be used for internal network. The result was intranet. Intranet has the following attributes.
Intranet is based on standards that are used with Internet
Intranet scope is limited to the organization level. In other words intranet can be accessed only with in an organization.
Intranet is primarily used to share the information among the employees of an organization.
Intranet can be considered as “private internet with only the relevant data”.
7.11.1 Setting up Intranet The question that you may have in your mind would be how to setup an intranet. Since intranet is based on internet standards you would be having many of the requirements of internet as follows:
Your network should have the support for TCP/IP.
If you wish to have file sharing then FTP support should be enabled.
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The servers have to be established. These servers would host the information that would be requested by the users. There can be individual servers for database, application etc.
Since the intranet is based on internet standards the clients for accessing the intranet are nothing but the web browsers. Here the selection of web browser can be made by keeping the organization's need in mind because here the boundary is restricted to an organization.
A network monitoring tool can also be used to monitor the functions or load of the intranet to facilitate better access.
Since the intranet is well defined i.e. you know the number of users, the servers can be tweaked for performance keeping in mind the number of concurrent users.
7.11.2 Advantages of Intranet Intranet has got the following advantages:
Since the intranet is limited to an organizational boundary it can be made more secure than the open internet.
Information can be distributed across organization easily and effectively.
During information distribution proper access rights can be set so that right information reaches right people at right time.
Intranet is platform independent i.e., part of an organization may be working with windows operating system and another part may be working with Linux operating systems. Still they would be able to access the intranet application because all the standards used with intranet is platform independent.
Intranet would improve collaboration between various teams working in an organization.
Through intranet a common standard can be shared across all the teams of an organization.
Delay in accessing information through intranet is very less.
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7.11.3 Disadvantages The following list gives you list of all factors that to be considered while setting up an intranet (in terms of disadvantages)
Need for expertise to manage the intranet.
Controlling the information overflow on intranet.
Finding the trade-off between rights given to the users and administrative restrictions.
A problem in the intranet server would degrade the performance of all the departments of the organization.
In addition to intranet, if internet access is given to the users then it become additional responsibility of the administrator to safe guard the sensitive data of the organization.
7.11.4 Extranet Extranet is similar to intranet except with a variation that the boundary is not strictly limited to the organization but authorized people outside the organization can also access the extranet. For example an organization may like to give access to some parts of its system to users like customers, vendors etc who reside outside the organization. In such a case you cannot use intranet. Here extranet can be successfully implemented. Access to the network would be on the basis of authorization. The users would be given user id and password which can be applied to access the resources. Apart from these user id and password based authorization there can be other methods of authorization like IP based authorization etc. In IP based authorization users would be checked for their IP. If the IP falls with in the specified list or specified range then access would be given. Otherwise access would be denied.
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7.12 HTML Hyper Text Markup Language (HTML) can be considered as a corner stone of World Wide Web. The pages of World Wide Web are constructed with HTML. HTML is a markup language. Markup languages are used to represent the form and structure of a document. Markup languages don't support any logical commands like programming languages. So, HTML also doesn't support any logical commands. The point you have to remember here is that HTML is not a programming language; it is only a markup language. HTML and all other markup languages are derived from SGML (Standard Generalized Markup Language). Many of the markup languages like XML etc are derivatives of this SGML.
7.12.1 Structure of a HTML document A HTML document is made up “tags”. A HTML tag would have the following syntax:
data For example
Pondicherry University . Here
the opening tag and
the closing tag
The data in between opening tag and closing tag would be applied the particular style provided by the tag. A HTML document has the following structure
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{contents} Any HTML document has to start with the tag and the same need to be closed at the end. The next tag would be and it would be closed before the tag. For example Welcome to Pondicherry University The HTML listing and the output is as shown in the figure 7.3 Figure 7.3 Simple HTML listing with its output 7.12.2 Steps for creation of first HTML file Following the steps given below to create a simple html page:
Open any text editor any type the above given code and save the by giving any name and .html extension.
Launch any web browser and open the html file to view the output.
7.12.3 Parts of an HTML document A html document has two sections. They are as listed below: 13.
Head Section
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14.
Body Section. Head section would hold certain specialized tags like
, <meta><br />
<br />
etc. In the body section the actual document layout would be created. Body section is the core section of any html document because only here the actual content of the document is given. Head section in html is optional. 7.12.4 HTML output The output of a HTML listing depends on various factors. Most important factors are as listed below: 23.<br />
<br />
The browser with which you are viewing the document has a major role<br />
<br />
in deciding the actual display because it is only the browsers which interprets the html code and display the output. 24.<br />
<br />
The operating system that you use would also play a major role in<br />
<br />
displaying the page. 25.<br />
<br />
The display resolution (like 800 x 600 etc) would have an impact on the<br />
<br />
actual page display. It is always to better to keep in mind the target users and design the pages with those features which would be rendered in a best manner. For example in many web sites you would have a message similar to “This page would be rendered optimally in IE version 5.0 or above”. This indicates that the target users of that site has to use the Internet Explorer version 5.0 and above to get the exact output as the designer has created. 7.12.5 Widely Used HTML tags It would be out of scope of current text to describe about all the html tags in detail because the number of html tags is very huge in nature. This section would provide introduction to widely used html tags.<br />
<br />
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<br />
7.12.5.1 Title Tag Title tag is used to specify a title to the document. Title has to reflect the summary of content of that html document. Title would be displayed on the title bar of the browser window. Figure 7.4 Title Tag The title tag has to be specified in the head section. Some of the tags that are specified in head section would have certain control features. For example the “meta” tag can be used to specify keywords to the search engines and to specify the interval in which the page has to be reloaded. 7.12.5.2 Paragraph tag To start a new paragraph you can use the <p> tag. For example: Figure 7.5 Paragraph Tag You can look at the third <p> tag in which an attribute “align” has been specified to align the paragraph to right. You can notice the output where the third paragraph is aligned to right. HTML attributes are used to specify properties of the tag. HTML attribute values are given with in quotes. However these quotes are not mandatory. 7.12.5.3 Bold, Italic and Underline Bold, Italic and underline are used to emphasis particular phrase or portions of a document. HTML provides three different tags for doing the same. <b> and </b> for Bold, <i> and </i> for italic, <u> and </u> for underlining.<br />
<br />
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<br />
For example <b> This is bold text </b> <u> this is underlined text </u> <i> this is italicized text </i> 7.12.5.4 Starting a new line To start a new line html provides a tag called <br>. <br> refers to break. <br> is a pair less tag i.e. There is no closing tag for <br>. Few tags in html are without closing tags. For example: <body> This is line one <br> this line two <br> line 3 </body> 7.12.5.5 Inserting a horizontal Line To insert a horizontal line the <hr> tag can be used. For example <body> This is group 1 <hr> This is group 2 </body> The above html listing would provide the output where there is a horizontal rule is provided in between the two lines. 7.12.5.6 Linking to other page Most important attribute of html document is the ability to link from one document to another. To provide this facility html has got the link tag <a> </a>. In addition to liking other documents portions of same document can also be given as target for anchor tag.<br />
<br />
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<br />
For example <body> <a href=”www.podiuni.edu.in” rel="nofollow"> Pondicherry University </a> <a href=”www.mkuniversity.org” rel="nofollow"> M.K. University </a> </body> The above listing would produce an output consisting two hyperlinks. By clicking the hyperlinks your browser would land on to the corresponding URL given for those links. 7.12.5.7 Inserting Images HTML is not only for text data. It has the capability to handle various forms of data like image, audio etc. To insert an image in to an html document <img> tag is used. For example: <body> Taj Mahal <img src=”tajmahal.jpg” width=”100” height=”100> Himalayas <img src=”himalayas.jpg” width=”100” height=”200”><br />
<br />
</body> The output of above listing would be a page containing images of tajmahal and himalayas. Also the text “Taj Mahal” , “Himalayas” would be displayed. The width and height attributes specifies the width and height of the images. 7.12.5.8 Creating Tables Many times it is required to give the data in a tabular format. HTML provides table tag to create tables. Table creation involves various tags. They are as listed below: <table><br />
<br />
- To specifiy table beginning and ending<br />
<br />
<th><br />
<br />
- To specifiy table header<br />
<br />
<tr><br />
<br />
- To specifiy beginning of a new row<br />
<br />
<td><br />
<br />
- To specifiy a cell<br />
<br />
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<br />
For example Figure 7.6 Table Tag There are various attributes that you can use with in a table definition. Few of them are listed below: 21.<br />
<br />
border<br />
<br />
- To specify the thickness of table borders<br />
<br />
22.<br />
<br />
width, height - To specify width and height of the table.<br />
<br />
23.<br />
<br />
Cellspacing<br />
<br />
24.<br />
<br />
Cellpadding<br />
<br />
25.<br />
<br />
Rowspan<br />
<br />
- To indicate number of rows to span<br />
<br />
26.<br />
<br />
Colspan<br />
<br />
- To indicate number of columns to span.<br />
<br />
- Space between two cells - Space between the cell content and cell border<br />
<br />
Apart from creation of tables, the table tag has got an important usage. Another usage of table tag is to align the contents. HTML doesn't provide any coordinate based positioning. So to properly create the layout of pages table tag is used. In these cases the border property of table tag would be set to zero so that the table will not be visible to the end user. 7.12.5.9 Listing Tags To create list html provides listing tags like ordered listing and unordered listing. An example for unordered list is given below: <body> <ol> <li> CPU </li> <li> Mother Board </li> <li> RAM </li> </ol> </body><br />
<br />
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<br />
The above example would display a list with three items in it. Each item would be displayed in a separate line. They would be preceded with symbols (like bullets) to identify them as individual item. These bullets are also customizable. In case of ordered list instead of <ol> the tag <ul> would be used. And the output would have numbers instead of bullets. 7.12.5.10 Marquee tag Marquee tag is used to scroll text on the display to get attention from the user. For example: <body> <marquee> This text would be rolling </marquee> </body> The direction and speed of rolling can be controlled with the help of various parameters.<br />
<br />
7.12.6 HTML vs. XHTML XHTML is a variation of html based on XML. The important variations between HTML and XHTML are as listed below: 29.<br />
<br />
HTML tags don‟t make it mandatory to close the tags where as in<br />
<br />
XHTML it is mandatory to close all the tags. If the closing tag does not exist then also there is a special mechanism. For example <br> would be used in XHTML as <br /> 30.<br />
<br />
The attribute values in XHTML must be given within quotes where as in<br />
<br />
html it is optional.<br />
<br />
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<br />
31.<br />
<br />
The nesting of tags in XHTML should be proper otherwise it would<br />
<br />
through a error message. In HTML proper nesting is not mandatory. HTML allows to close the tags in improper nesting manner also. All the above steps are taken to insist the proper output of HTML in all the browsers and in all the platforms. So XHTML is now becoming the de-facto standard for web development. XHTML is not entirely a new markup language rather it is a variation of HTML where rules have become tougher. Though html is widely used there is a general criticism of html. It is given as follows: HTML clubs the presentation with data too much. So if you want to change the layout at a later point it becomes very difficult. In order to solve the above problem there is a technique introduced called CSS (Cascaded Style Sheets). In CSS the style alone would be defined. Later this style would be attached to html. By this html becomes more modular. By the integration of CSS with HTML, the pages would become easily modifiable for their style. So this HTML and CSS combination has become a great success in the World Wide Web development.<br />
<br />
Summary Internet is the global network. Internet is called network of networks. The history internet began with ARPANET. There are various modes of connecting to internet: dial-up, broadband access etc. The organization which provides you the access to internet is called Internet Service Providers (ISP). For example BSNL. Modem is the device used to convert analog signals to digital and vice-versa.<br />
<br />
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<br />
There are various protocols associated with internet: TCP/IP, HTTP, FTP etc. IP stands for Internet Protocol. Every computer connected to internet would have an internet protocol address. IP can be static or dynamic in nature. Domain name systems are used to convert the URLs into IP address for fetching the content associated with them. Domain name system is one of the largest distributed databases. The software that is used to access the World Wide Web are called as Web browsers. For example Internet Explorer, FireFox etc. Internet and World Wide Web are not interchangible terms. Internet is the underlying network and WWW is one of the applications running on internet. E-mail is used to communicate message among users. To access the email facility an e-mail account is needed. The e-mails can be accessed either through the e-mail client or web based interfaces. Popular examples for e-mail services are Gmail, Yahoo mail etc. FTP stands for File Transfer protocol. It is used to transfer files from one system to another system provided they are connected with internet and the FTP support is provided. Generally FTP is not secure but the FTPS version is comparatively securer than FTP. Bulletin Board Systems were very popular during 80s and early 90s. After the large scale growth in World Wide Web, the bulletin board systems have become less popular. Intranet is a local network which uses the standards and technologies of internet. Intranet would be accessible only with the organization. Extranet is an extension to intranet. Extranet can be accessed by authenticated people outside the organization also.<br />
<br />
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<br />
Self Assessment Questions Part I (Multiple Choice Questions) 22.<br />
<br />
The birth of internet is associated with<br />
<br />
1. ARPANET 2. Google 3. Netscape 4. All of the above 5. None of the above 23.<br />
<br />
IP stands for<br />
<br />
1. Internal Programming 2. Internet Permissions 3. Internet Protocol 4. All of the above 5. None of the above 24.<br />
<br />
Which of the following is not a web browser?<br />
<br />
1. Internet Explorer 2. Chrome 3. iBrowse 4. All of the above 5. None of the above 25.<br />
<br />
Safari is the browser associated with<br />
<br />
1. Macintosh 2. Unix 3. DOS 4. All of the above<br />
<br />
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<br />
5. None of the above 26.<br />
<br />
Firefox versions are available for<br />
<br />
1. Windows 2. Linux 3. Macintosh 4. All of the above 5. None of the above 27.<br />
<br />
Which of the following is not a markup language?<br />
<br />
1. HTML 2. XML 3. PHP 4. All of the above 5. None of the above 28.<br />
<br />
The tag in html which is used to insert a new line is<br />
<br />
1. <nl> 2. <br> 3. <enter> 4. All of the above 5. None of the above 29.<br />
<br />
The html tag used to draw horizontal ruler is<br />
<br />
1. <hr> 2. <hrule> 3. <hori_ruler> 4. All of the above 5. None of the above<br />
<br />
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<br />
30.<br />
<br />
HTTPS stands for<br />
<br />
1. HTTP secure 2. HTTP simple 3. HTTP synchronous 4. All of the above 5. None of the above 31.<br />
<br />
Gecko is the rendering engine for<br />
<br />
1. Firefox 2. Internet explorer 3. Safari 4. All of the above 5. None of the above Part II (Short Questions) 19.<br />
<br />
Explain the function of modem.<br />
<br />
20.<br />
<br />
What do you mean up dial-up connection?<br />
<br />
21.<br />
<br />
List out four internet protocols?<br />
<br />
22.<br />
<br />
Differentiate internet and WWW.<br />
<br />
23.<br />
<br />
List out the names of popular web browsers.<br />
<br />
24.<br />
<br />
What do you mean by DNS?<br />
<br />
25.<br />
<br />
Write short notes on intranet.<br />
<br />
26.<br />
<br />
List out any three e-mail client programs. Part III (Descriptive type Questions)<br />
<br />
19.<br />
<br />
Compare and Contrast various Web browsers.<br />
<br />
20.<br />
<br />
Explain in detail about e-mail services.<br />
<br />
21.<br />
<br />
Explain the importance of HTML with clear examples.<br />
<br />
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<br />
Answer Key Part I 1. a<br />
<br />
2. c<br />
<br />
3. c<br />
<br />
4. a<br />
<br />
5. d<br />
<br />
6. c<br />
<br />
7. b<br />
<br />
8. a<br />
<br />
9. a<br />
<br />
10. a Part II<br />
<br />
11.<br />
<br />
Modem is used to establish the link between a computer and<br />
<br />
telecommunication network. The role of modem is to convert the analog signals into digital and vice-versa. 12.<br />
<br />
There are many ways of accessing internet. One such way is called dial-<br />
<br />
up connection. In dial up the ISP will provide a number to dial using which the connection would be established. The dial-up connections are normally slower in nature. 13.<br />
<br />
A protocol is a set of rules to be followed while making communications<br />
<br />
in networks. Some of the popular internet protocols are as listed below: (a) TCP /IP (b)HTTP (Hyper Text Transfer Protocol) (c) FTP (File transfer protocol) (d)IMAP (Internet Mail Access Protocol 14.<br />
<br />
The terms www and internet are not synonyms. Internet refers the<br />
<br />
underlying the network and www is only application running on internet. 15.<br />
<br />
A web browser is software used to access the World Wide Web. There<br />
<br />
exists an array of web browsers today. Some of them are listed below:<br />
<br />
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<br />
(a) Mozilla Firefox (b) Internet Explorer (c) Google Chrome (d) Safari 16.<br />
<br />
DNS stands for Domain name systems. The name systems role is to<br />
<br />
convert the user entered URL into IP address. If domain name systems were not there users have to remember the IP addresses which is very difficult to practice. 17.<br />
<br />
Intranet is a local network which is based on the standards and<br />
<br />
technologies of internet. The boundary of intranet is only within an organization. When the authorized users outside the organization are allowed to access then it becomes extranet. 18.<br />
<br />
The e-mails can be accessed either through World Wide Web or e-mail<br />
<br />
clients. E-mail clients are software which you can install in your machine to access your e-mail account. Popular e-mail clients are (a) Mozilla Thunderbird (b) Outlook Express (c) Evolution<br />
<br />
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<br />
Lesson 8: Multimedia Introduction <br />
<br />
Today we are all living in the information technology world. The role of computers in human life has become inevitable. One of the major causes for computers becoming part-and-parcel of everybody‟s life is because of the simplicity of its usage. Gone are the days when computers were only for technology oriented people.<br />
<br />
<br />
<br />
Nowadays usages of computers have become very common across people who are not basically technical. Major reason behind this change is that “computers have become user-friendly”.<br />
<br />
<br />
<br />
Can we now imagine a computer that does not has the capability to display images? It may sound very uncommon today. The power of computers lies in their ease of use. The factor behind the ease of use is that the computers now have the capability to handle multiple media.<br />
<br />
<br />
<br />
This lesson would focus on various aspects of multimedia.<br />
<br />
Objectives <br />
<br />
Defining the term multimedia<br />
<br />
<br />
<br />
Explaining various components of multimedia<br />
<br />
<br />
<br />
Introducing various file formats<br />
<br />
<br />
<br />
Explaining the multimedia requirements<br />
<br />
<br />
<br />
Elaborating the challenges associated with multimedia<br />
<br />
8.1 Multimedia - definition The term multimedia is derived from two Latin words. They are multum + media. “Multum” means many. Media refers to a form of communication. In general we can define multimedia as the combination of more than one form of content forms.<br />
<br />
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<br />
A computer is said to be multimedia enabled if and only if it has the capability to handle multiple content forms like text, graphics, audio, video etc. Before exploring the inner details of multimedia we need to first get acquaintance with the various types of media stated above. The next section would focus on various components of multimedia<br />
<br />
8.2 Components of multimedia Various components of multimedia have been listed below: <br />
<br />
Text<br />
<br />
<br />
<br />
Graphics (still images)<br />
<br />
<br />
<br />
Animation<br />
<br />
<br />
<br />
Audio<br />
<br />
<br />
<br />
Video The fig 8.1 illustrates various components (content forms) of multimedia.<br />
<br />
8.2.1 Text The “text” component consists of only the alphabets, numerals and special characters. This is the most preliminary content form. The text component itself has various effects associated with it. They are as follows: <br />
<br />
Font face<br />
<br />
<br />
<br />
Font size<br />
<br />
<br />
<br />
Character spacing<br />
<br />
<br />
<br />
Other effects like bold, italic, underline etc. The usage of text medium in a multimedia content becomes very crucial.<br />
<br />
At the same time the amount of text that would be used in the multimedia presentation should also be under control. We should not overuse the text content in a multimedia presentation.<br />
<br />
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<br />
Fig 8.1: various content forms of multimedia<br />
<br />
8.2.2 Graphics Graphics refers to still images. An image is nothing but a matrix of pixels (pixels refers to the picture cells). With the help of image we make the content to be more effective because an image is worth more than thousand words. There exist various kinds of images that can be used in a multimedia presentation. The following table 8.1 lists out various image file formats and their explanations. Image format<br />
<br />
Meaning<br />
<br />
Bmp<br />
<br />
Bitmap image.<br />
<br />
Jpeg<br />
<br />
Joint photographic experts group<br />
<br />
Png<br />
<br />
Portable network graphics<br />
<br />
Tiff<br />
<br />
Tagged image file format<br />
<br />
Gif<br />
<br />
Graphics interchange format Table 8.1: various graphics file formats and their meanings<br />
<br />
While selecting an image we need to find the trade-off between the memory requirements and quality of the image. Bitmap (bmp) is the uncompressed image file format. It is widely used with Microsoft windows operating systems. Bitmap uses 24 bits per pixel. The total number of colors possible with bmp format is around 16 millions. Tiff file provides better quality images. But the size of tiff images is very high. It also uses 24 bits per pixel. Among the above given list of file formats gif and jpeg formats are widely used in World Wide Web. The reason for their usage is that the file size<br />
<br />
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<br />
is smaller, so it is easy to transfer these file over internet because they consume very less storage space. Let us have a glance on these two file formats.<br />
<br />
8.2.2.1 Gif format Gif stands for graphics interchange format. Facts about gif are given in the following list: <br />
<br />
Gif is a compressed file format.<br />
<br />
<br />
<br />
The algorithm used for compression in gif is LZW.<br />
<br />
<br />
<br />
Gif uses 8 bits per pixel. So the maximum number of colors with gif image is 256<br />
<br />
<br />
<br />
The compression ratio of gif image is around 1:10.<br />
<br />
<br />
<br />
The gif format is supported by most of the web browsers. This makes gif a good choice for World Wide Web.<br />
<br />
8.2.2.2 Joint photographic expert group (jpeg) Another image format that is widely in internet is the jpeg. The facts about jpeg are listed in the following list: <br />
<br />
This jpeg format has been introduced by a group of experts.<br />
<br />
<br />
<br />
Jpeg format works very well with multi color images.<br />
<br />
<br />
<br />
Jpeg compression is a loosy compression method but still human eyes are not capable of identifying those lose.<br />
<br />
<br />
<br />
Most of the image processing tools provide various levels of compression for jpeg. As the compression increases image size is reduced at the same time quality of the image is also reduced. Generally for compression of images various algorithms are used. They<br />
<br />
fall under the techniques like run length encoding (RLE), statistical compression etc.<br />
<br />
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<br />
8.2.3 Animation Any object in a multimedia presentation that has movement associated with it, is called animated. The fundamental usage of animation is that they can be used for some illustration purpose. An animation is again a sequence of continuous still images arranged in a specific order so that it creates the illusion of movement. So to create an animation sequence we need to create the required still images first. Then we can combine these still images using specific tools to create the animation. Smoothening of images edges to improve the look of the image is called “anti-aliasing”.<br />
<br />
8.2.4 Audio Audio component adds the real richness to any multimedia presentation. The audio can range from human voice to special effects sound. In order to handle audio in a presentation we need to first capture the audio. Then we should integrate the audio in proper place in to the presentation. There exist various kinds of file formats for audio. Some of them are listed below: <br />
<br />
Wav (wave file)<br />
<br />
<br />
<br />
Mp3<br />
<br />
<br />
<br />
Wma (windows media audio)<br />
<br />
<br />
<br />
Ra (real audio)<br />
<br />
8.2.5 Video Animations are artificially created sequence of events where as video refers to captured sequence of real events. The usage of video in a multimedia presentation lies where we need to integrate some clips of recorded events. To handle video we have specific file formats like dat, mpeg4 etc.<br />
<br />
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<br />
Interactivity is also considered another important aspect of multimedia. Any multimedia presentation would be more effective if it has provisions for human interactions.<br />
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8.3 Multimedia requirements In order to handle multimedia we have certain requirements to be satisfied. This section would illustrate both the hardware and software requirements for handling multimedia. Hardware requirements of multimedia includes a good quality video display, speaker system with microphone to capture audio, an high amount of main memory and hard disk space. With respect to software the requirements include various authoring tools for all kinds of media. There exist certain popular multimedia tools. For still image related tasks we can use adobe Photoshop. There are other alternatives like gimp (gnu image manipulation program) etc. In combination with this CorelDraw is also very useful. To create animations we have plenty of tools like Corel rave, macromedia flash. Using macromedia flash we can create powerful two dimensional animation sequences. To create three dimensional animation sequences we can use “Maya”, the most popular tool in the multimedia world. Using Maya we can create virtual characters with certain behaviors. The names of tools specified above are only representative. We have a large collection of tools available for multimedia purposes. A complete illustration of all the tools would be out of scope of this text. The next section would focus on various applications of multimedia.<br />
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8.4 Multimedia applications The applications of multimedia are widespread. We would explore few of the important applications in this section.<br />
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8.4.1 Education The applications of multimedia in the field of education are many. Elearning itself, has become a vast field. Multimedia based presentations have become common teaching tool in institutes of higher learning. The important benefits of this method includes <br />
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Students can visualize the concepts in a much easier way.<br />
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Comparing to the traditional black board based teaching you can speed up the learning process.<br />
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Lecture sessions can be made more interactive with the help of multimedia tools.<br />
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Particularly to the students of distance learning, multimedia presentations would be very useful in-addition to the traditional paper based study materials.<br />
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8.4.2 Telemedicine The effectiveness of telemedicine is primarily due to faster communication links and multimedia. The telemedicine would not have been successful to this extent without the help of multimedia. The multimedia applications in telemedicine include video transmission of patient diagnosis or surgery. The sound is also transmitted live to facilitate communication between patient and doctor, doctor and doctor communication. There exists few telemedicine software commercially available in the industry. They all incorporate excellent multimedia capabilities.<br />
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8.4.3 Entertainment industry One of the prominent industries which got benefited by multimedia is the entertainment industry. The application of computer animation sequences in movies is one the well known examples for multimedia applications. Application of multimedia enriches the quality and reach y of the movie to a greater extent.<br />
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8.4.4 Virtual reality The latest development in the field of multimedia is virtual reality. Virtual reality is the creation of illusion of an environment through the help of multimedia. With the help of virtual reality the user can mentally be transferred to any environment though he/she may be physically present in some other environment. For example with the help of virtual reality we can provide virtual laboratories to the students where in they can perform the experiments virtually. Another example could be to create the simulation of vehicle control for drivers. With this technology the trainee drivers can get an experience of controlling the vehicle without even entering in to it. This method greatly reduces the cost. We can certainly ensure the prevalence of virtual reality in many fields in near future.<br />
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8.5 Multimedia – challenges Although multimedia provides lots of advantages we need to face certain challenges while using multimedia. First of all the requirements stated earlier should be satisfied. One of the important facts to consider about multimedia is that all the content forms except text would require a huge storage space. The solution to this problem is compression i.e. All the content forms can be converted to a format where they require much lesser memory than their original form.<br />
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For each content form there exists a specific compression standard. For example to compress audio the recent technique is mp3. The popularity of mp3 is well known to all. With the help of mp3 we can reduce an audio file of size 70 mega bytes to 4 mega bytes. Another important reason for compression is that when the multimedia content travels through a network they require huge band-width without compression. If we compress the multimedia content, then it would occupy comparatively very less band-width.<br />
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Summary <br />
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Multimedia refers to various content forms of data.<br />
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Various of forms of data includes text, image, audio, video<br />
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The compressed file formats like GIF and JPEG are widely used on internet.<br />
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There exist many specialized multimedia software.<br />
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Applications of multimedia are there in various fields. For education, telemedicine, entertainment, virtual reality etc.<br />
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Multimedia data requires a high bandwidth network for faster transfer.<br />
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Self Assessment Questions Part I (Multiple Choice Questions) 1. Which of the following is not a compressed image file format? <br />
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Bmp<br />
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Jpeg<br />
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Gif<br />
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All of the above<br />
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None of the above<br />
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Smoothening of image edges to make them look better is called <br />
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Shading<br />
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Sliding<br />
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Anti-aliasing<br />
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All of the above<br />
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None of the above<br />
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Which of the following is/are image processing software? <br />
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GIMP<br />
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Photoshop<br />
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Corel draw<br />
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All of the above<br />
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None of the above<br />
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Which of the following is/are audio file format(s) <br />
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.mp3<br />
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.wav<br />
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.ra<br />
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GIF image is best suited for <br />
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Large images<br />
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Gray scale images<br />
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Multi-color images<br />
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Part II (Short Question) <br />
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Define multimedia<br />
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List out various content forms of multimedia.<br />
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Write short notes on virtual reality.<br />
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What do you mean by anti-aliasing?<br />
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Write short notes on “JPEG” Part III (Descriptive type Questions)<br />
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Explain the applications of multimedia in various fields<br />
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Elaborate on various components of multimedia.<br />
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Answer Key Part I 1. a<br />
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2. c<br />
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3. d<br />
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4. d<br />
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5. b Part II 6. Multimedia refers to the integrated usage of more than one media together. Multimedia requires certain specialized hardware and software for efficient performance. 7. Multimedia includes various content forms. They are as listed below: <br />
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Text<br />
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Graphics<br />
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Animation<br />
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Audio<br />
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Video<br />
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8. With the help of virtual reality you can provide the user a feel that the movements are happening in the real world. For example you can provide a walk-through inside a building as if user is walking through the building. 9. Smoothening of image edges so that the image would look better is called anti-aliasing. It is used to increase the quality of the image. 10. JPEG stands for Joint Photographic Experts Group. It is an image format well suited for multi colored images. JPEG images provide a good level of compression.<br />
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Lesson 9: Object Oriented Systems Introduction <br />
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There exist many paradigms of programming. Object Oriented System is one of the approaches towards software development.<br />
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Object Oriented Systems provide various advantages over other systems.<br />
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This lesson would elaborate on object oriented systems covering details like their origin, fundamental concepts, comparison with other systems etc.<br />
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Objectives <br />
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Providing an introduction to Object Oriented Systems<br />
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Explaining various concepts of Object oriented Systems<br />
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Explaining advantages of Object Oriented systems.<br />
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9.1 History of Object Oriented Systems Object oriented System came in to existence a long time back. During 1960s itself, there were talks about object oriented systems. During that time only few languages were there to support object oriented systems. But nowadays you have an array of programming languages which either supports object oriented programming concepts completely or partially. Simula language was the first language which incorporated into object oriented programming concepts. Simula was developed as superset of Algol. Simula was developed during 60s. Simula supported many object oriented programming concepts like Classes, objects, virtual methods etc. The next language to rise in the object oriented arena was “Smalltalk”. Smalltalk was introduced during the 70's. Smalltalk was based on Simula. Smalltalk supported many more features than Simula. It is only the after the<br />
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raise of Smalltalk the term “Object Oriented Programming” became popular across the Information Technology world. Many programming languages developed later supported concepts introduced by Simula. C++ also has got greater impact of Simula. Now the list of languages that support object oriented concepts is lengthier. Some of the popular languages that support object orientation are listed below: <br />
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C++<br />
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Java<br />
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Small talk<br />
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PHP<br />
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Objective-C etc. Though many languages were developed following Simula and<br />
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Smalltalk, it is only the C++ which attracted a larger mass of developers towards object oriented programming. The object oriented programming attained much popularity during 90's. Once the concept of Graphical User Interface was introduced, the object orientation techniques were suited optimally to them. Later most of the visual programming languages supported the object oriented system concepts. Nowadays object oriented system concepts are widely used in the Web Scripting languages also (Both in client as well as in server side). For example the recent version of server side scripting language PHP supports object orientation to a greater extent. In the case of Client side scripting also JavaScript provides support to object oriented concepts. Most of the languages today are either completely object oriented or they support object oriented concepts. The reasons for this support are explained in later portions of this text.<br />
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9.2 Object Oriented Vs Object based languages There are certain languages which supports few object oriented concepts but not all concepts. In this section the difference between Object oriented and object based languages are discussed. There exist certain languages where even the smallest program that you can develop should also use object oriented concepts. These types of languages would support most of the concepts of object oriented systems. These languages are called strictly object oriented. For example <br />
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Smalltalk<br />
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Ruby etc. There are certain other languages where you either follow object<br />
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orientation or omit them. For example in C++ language you can construct program that doesn‟t touches any concepts of object orientation. There are other languages which are based on the object orientation concepts. For example in a language like Visual Basic you have the concept of object, classes etc. But it is not object oriented programming language because it doesn‟t support many object oriented concepts like inheritance etc. The choice of language selection can be done on the basis of application that you are going to develop and the target hardware. 9.3 Object Oriented programming concepts A program in an Object oriented programming language would be collection of objects and interactions between these objects. This section would describe the fundamental concepts of object oriented programming. They are as listed below: <br />
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Objects<br />
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Classes<br />
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Encapsulation<br />
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Polymorphism<br />
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Inheritance<br />
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9.3.1 Objects Objects are the fundamental units of Object Oriented programming. From the term itself you can understand that these programming languages are totally based on objects. An object is an instance of a class. An object would hold the data and the functions (that would operate the data together). An object would provide some mechanisms in the form of functions using which the external world can access the data members of objects. 9.3.2 Classes A class is blueprint using which the objects are created. Class consists of two components. They are member variables and member functions. These member variables and functions would have various access modifiers like private, public, protected. A Class can have relationship with other classes. For example you can consider “vehicle” as a class. The class for defining vehicle would have members like “number of wheels”, “fuel type”, “color” etc. An object belonging to the class “vehicle” would have corresponding values for these variables. For example you can consider “Maruti-800” as object for this class. Here the values would be filled for variables specified above. “Number of wheels” would be filled with 4, “color” with blue etc. Many such real world examples can be given. For example, “animal” is a class and “Lion” is an object belonging to the class. In general all the objects created using a particular class would have most of the common properties. Here you have to remember one thing that the values of properties can differ for each object. For example “Animal” class can have property like “type”, the values can be different for this properties which may include “herbivorous”, “carnivorous” etc.<br />
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9.3.3 Encapsulation Encapsulation is the process of binding many items together so that they can be accessed easily as a single unit. You can visualize the concept of encapsulation in terms of “capsules”. In capsules more than one type of medicine is put together and given to the patient as a single unit. The consumers of the capsule need not to know about the internal elements of medicines present in the capsule. For him the capsule is a single unit. Similarly in the case of Object oriented programming various units like data and the functions to access those data are put together. The user is not required to handle these pieces individually. They can be handled as single unit. This process is called encapsulation. The access points to the objects would be clearly defined. Generally these access points are member functions. The data associated with an object is not directly manipulated by external world. It is these functions which acts as the interface to the data associated with the object. But there is an exception to this phenomenon. When the data associated with object is declared as “public” then it can be accessed directly. In general encapsulation hides the internal operations to the external world. It gives you the interfaces using which the associated data can be manipulated safely. 9.3.4 Inheritance The most important feature of Object Oriented programming is the concept of inheritance. The inheritance of Object oriented programming can be compared with human inheritance. A child would inherit traits (characteristics) from the parents. In addition to that the child can have it's own special characteristics.<br />
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The inheritance in OOP is also the same. Here a class would inherit properties and methods from another class. The reason for which inheritance is getting popular is the concept of “reusability”. Reusability provides you the advantage that every time you need not start from the scratch. You can create new classes which would inherit from the existing classes. There exist many types of inheritance. They are as listed below: <br />
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Single level inheritance or simple inheritance<br />
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Multi level inheritance<br />
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Hierarchical inheritance<br />
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Multiple inheritance<br />
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Hybrid inheritance<br />
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9.3.4.1 Single level inheritance or simple inheritance In the case of simple inheritance there is only one base class and one derived class. Base class is the class which already exists. Derived class is one which inherits the properties from the base class. For example Figure 9.1 Simple Inheritance<br />
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9.3.4.2 Multi level inheritance In the case of multi-level inheritance classes would be derived from other classes which are derived classes themselves. For example class B derives Class A and Class C is derived from Class B then it is called multi level inheritance.<br />
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In other words in the case of multi level inheritance few classes are both derived classes as well as base classes. Figure 9.2: Multilevel Inheritance 9.3.4.3 Hierarchical inheritance In the case of hierarchical inheritance more than one class would be derived from a single class. For example if there are two classes Class B and Class C which are derived from Class A then it is called hierarchical inheritance.<br />
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Figure 9.3: Hierarchical Inheritance<br />
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9.3.4.4 Multiple Inheritance In the case of multiple inheritance a single class would have been derived from more than one base class. For example if there is Class C which is derived from both Class A and Class B then it is called multiple inheritance.<br />
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Figure 9.4: Multiple Inheritance<br />
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Multiple inheritance is not directly supported in some of the object oriented languages like Java etc. 9.3.4.5 Hybrid Inheritance When more than one type of inheritance is mixed together it becomes hybrid inheritance. For example multi level and hierarchical inheritance can be<br />
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clubbed together to form hybrid inheritance. You can select more than one type of inheritance and use them in a combined manner then it becomes hybrid inheritance. Figure 9.5: Hybrid Inheritance<br />
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9.3.5 Polymorphism The term polymorphism is combination of two terms viz., poly + morphic many faces. In polymorphism the same entity would have different meaning in different places. There exits two types of polymorphism. They are <br />
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Compile type polymorphism<br />
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Run time polymorphism<br />
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In the case of compile type polymorphism the binding would happen at compile time itself, where as in the case of runtime polymorphism the binding would happen at run time. Object oriented programming has concepts where the idea of polymorphism is effectively used. For example: <br />
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Function overloading<br />
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Operator overloading<br />
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In the function overloading two functions would exist with the same name. Which function is to be called would be decided based on many of the factors as given below: <br />
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Number of parameters of the functions<br />
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Data type of parameters of the functions<br />
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For example if there are two functions with the same name say “interest”. Then these versions should differ either in terms of number of arguments or data type of the argument.<br />
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Based on the calling location parameters the appropriate function would be invoked. Function overloading is certainly one of the repeatedly used concepts in object orientated programming. Another concept is the operator overloading. In the case of operator overloading, an operator is defined to be used differently at different places. For example you can define the operator “+” to work with “complex number addition”. (By default “+” would perform its operations on basic data types like integer and float etc). Important points to remember with operator overloading are as given below: <br />
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The basic meaning of the operator is not changed i.e., the operator “+” is not overloaded to perform the “-” operation.<br />
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There are certain operators which cannot be overloaded. For example the scope resolution operator used with C++ language i.e., “::” cannot be overloaded. Apart from the object mentioned concepts there exist some terminology<br />
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associated with object oriented programming. Some of them are described in the following paragraphs: 9.3.6 Instance An object created from a class is called an instance of the class. Each instance of the class would occupy some amount of main memory. The values associated with each instance may be different. (Except for static members; in the case of static members value is shared across all the instances). 9.3.7 Access Modifiers Access modifiers are used to define the scope of the variables used. There exist three commonly used access modifiers. They are<br />
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Public: The public variables can be accessed freely with the help of objects. You can associate a public variable with the object name and use them directly. For example object_name.variable_name is the common syntax in most of the programming languages.<br />
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Private: Private variables are accessible only with in the class. They cannot be used directly from outside the class.<br />
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Protected: Protected variable is accessible to the class holding it and the immediate derived classes.<br />
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These access modifiers can be used effectively to protect the data from unwanted access. Apart from variables the member functions can also be assigned access modifiers. 9.3.8 Constructors Constructors are the specialized member functions which would be called automatically during the object creation. The constructors are generally used to initialize values. Constructors can also be overloaded i.e., you can have more than one constructors. Corresponding constructors would be invoked based on the number and type of parameters present. Generally constructors have the same name as the name of the class. But this is not the mandatory condition in some of the languages like PHP. (In PHP you have specialized constructor called __construct). Constructor themselves are not mandatory. If you wish then you can include constructors. At the same time you can create classes with out constructors also. 9.3.9 Destructors Destructors are antonyms to constructors. Destructors would be called when object has no more references. Destructors would also have the same<br />
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name as the class (but proceeded with the symbol “~” in programming languages like C++). Destructors would be primarily used to free-up the memory occupied by unwanted resources. In parallel with constructor, there is no need to call the destructors also explicitly. 9.3.10 Abstract Classes An abstract class is a class for which objects cannot be declared. Now you may have a question that if objects are not going to be created then what is the usage of creating such a class. The answer for the above question is as follows: Abstract classes would acts as base classes. For those derived classes objects would be created. An abstract class would have method (member function) which is simply declared and not defined. This function or method is called abstract function or abstract method. This abstract method would be defined in the derived class of this abstract class. Abstract classes are very much useful when you require certain type of functions in all the classes. In such a case you can create an abstract class and make other classes as derivatives of this abstract class. Those functions can then be defined according to the need. 9.3.11 Static members When a member is declared as static then it is common across all the instances of that class. Generally all members of the class would be specific to each object i.e., the values would differ. But when the member is static then it would have the same value for all the objects. Static members can be accessed by directly using the class name instead of object name. Generally member variables and functions would be accessed by<br />
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using the object name. But the static members are directly accessed through the class name itself. Generic use of static member is to use them for counting purposes. Since the values associated with static members would retain across all the instances it would be easy to identify the number of objects created for that class using static variables. 9.3.12 Friend functions The functions which are declared as friend functions can use the members of a class for which it has been declared as friend. As we stated in the case of access modifiers, the members would have strict access restrictions based on its type of access modifier. The friend functions would get the freedom to access the members of a class which are not accessible by others outside the class. The usage of friend functions has to be proper; otherwise it may totally disturb the security associated with object orientated programming. 9.4 Object Oriented Database Management Systems Object Oriented Database Management Systems (OODBMS) are relatively new technology in the world of databases. Most of the commercial applications would require databases to store values permanently and retrieve them effectively whenever required. Now the programming is object oriented but the database is still based on the relational model. OODBMS is an effort to replace the Relational Database Management Systems with object based technology. The concept of Object orientation would be used in OODBMS to store and retrieve.<br />
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By using OODBMS and OOP together, both the application and the database would be based on object oriented technologies. So it may produce better synchronization between application and the database. But still the OOBDMS have not become that much popular comparing with RDBMS. May be in the future these OOBDMS may occupy considerable amount of space in the database paradigm. 9.5 Object oriented design process If you want your application to be object oriented then certain steps or actions has to be followed. This section highlights these actions. <br />
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Identification of Objects: The first in this process is to identify objects. These objects would map the real world problem with the programming domain. So you have to identify the objects properly.<br />
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Deciding on the members: Once the objects are identified you have to finalize the members (both variables and functions) associated with the object. During this step itself, you have to decide the scope of each member i.e., whether they are public or private or protected.<br />
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Identifying the relationship: Identification of relationship among classes is another process. If you carry out this process carefully proper inheritance mechanisms can be used.<br />
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Collecting objects together: You can identify the objects that have features in common. Then you can group them together.<br />
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Idea of common super class: This is related to the previous step. You can create a common super class which would host many other classes. In larger commercial frameworks you can find out that most of the classes are derived from a common base class. By doing this, the further programming process becomes much simpler.<br />
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Appropriate member type: The members inside a class may belong to different types like static, abstract etc. This has to be decided well in<br />
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advance so that proper communication can be established between various components of the class hierarchy. The above mentioned actions are involved in the process of object oriented designing and development. 9.6 Advantages of Object Oriented Systems over Traditional Systems At this point you may be having a clear idea about object oriented systems. This section would focus on advantages of object oriented systems over traditional systems: <br />
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Reusability: Reusability is one of the biggest advantages of Object oriented systems. The ultimate aim of any software development process would be to reduce the time required for that. If every component has to be started from scratch then it would require lengthier time. Contrasting to this if the code which is available already is reused then it would shorten the development time. By using the inheritance concept the development time would definitely get reduced. So reusability becomes one of the major factors for which object oriented systems have become this much popular. Though you can reuse the procedures in traditional systems they are not as effective as reusing the classes by extending them with derived classes.<br />
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Abstraction: Object oriented systems provide higher level of abstraction than the traditional systems. Once the classes are well defined then they can be used without worrying about their internal working mechanisms. This level of abstraction is not possible in traditional systems. The idea of framework based developments is the result of abstraction. Because once you define the frameworks you can build your system on top of the framework which would provided you readymade functions for performing repeated<br />
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activities. For example Microsoft .NET framework provides you a well defined class hierarchy which you can effectively use in your programs. <br />
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Easier to modify: Object oriented systems comparatively easier to modify than the traditional systems. Since all the functions and variables are properly organized it becomes easy to modify the code as and when the requirement arises. The same is not true with traditional systems. Of course you can modify the traditional systems also but they would require much effort and time.<br />
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Improved readability: The object oriented code is easy to read. The reason for this is the similarity between the system and the real world problem. Since the objects in the real world are modeled in to the systems it becomes easier to read the code. The improved understanding of the code would lead to better usage of existing code there-by improving the concept of reusability. The modeling is not only at the level of object but also the type of operations that an object can perform is also there. By this you can easily understand the nature and purpose of the code written (even by some unknown programmer)<br />
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Easy to maintain: The software development cycle doesn‟t ends at implementation. There is another crucial strep called maintenance. If the software is not constructed properly then it would become nearly impossible to maintain the code. During the maintenance phase there would be minor changes arising. The system should be flexible enough so that these changes would be incorporated in to the system with out much effort. In the case of traditional systems the maintenance is a tedious process because in a larger system there may be many invisible links between various components. In the case of Object oriented systems you can identify these links well in<br />
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advance. So the ripple effects of modifying the code at one place would be better understood than the traditional systems. <br />
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Easy to test and debug: Testing and debugging is relatively simpler in the case of object oriented systems comparing to the traditional systems. As mentioned in the previous step the traditional system may have complex inter-connectivity among various components, it becomes difficult to test the code. More over when an error occurs, identification of location and cause of that error is complex in the traditional systems comparing to the object oriented systems. This is possible because object oriented systems have well defined class hierarchy. So the exact reason, location of the error can be identified easily.<br />
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<br />
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Data security: The object oriented systems make the data more secure. In the case of traditional system the security associated with data is very less. But in the case of object oriented systems it clearly specifies the accessibility of data. These access rights make the data more secure because now the data would be handled only with in the restricted set of functions (where the data is actually needed and they are authorized to access these data).<br />
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<br />
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Modular approach: The object oriented systems follow modular approach. The tasks that have to be performed is clearly separated among many well structured functions. Since the modular approach is followed it gives you all other related benefits like extensibility etc. You cannot expect the same in the traditional systems (to an extent which the object oriented system provides)<br />
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Ability to extend: When the new features have to be incorporated into the system, the object oriented programming approach would be more helpful in doing that. The concept of modifiability is different from extensibility. In the case of modifiability the existing code is<br />
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changed to accommodate minor changes. In the case of extensibility entirely new features can be incorporated into the system without disturbing much of the existing code. The object oriented systems are more extensible than the traditional systems. The reasons for this extensibility are the clear separation of roles in the systems. So when a roles changes or a new role comes-in they can be incorporated in to the system easily. <br />
<br />
Better memory management: Since the object oriented systems support the concepts of constructors and destructors memory can be managed in an effective manner. For example by using destructors the memory occupied by unwanted resources can be freed up. In the case of traditional system you cannot perform these tasks effectively. This is one of the major advantages of object oriented systems. The destructors for example would be automatically called when no more reference exist. So the developer is freed from calling these functions explicitly. Many object oriented programming languages like Java has garbage collection mechanisms. (Garbage collection mechanism is the process of freeing up memory from unwanted resources. Garbage collection would make the applications faster and effective because the memory freed by garbage collector from unwanted resources can be effectively used for other productive purposes).<br />
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Uniform approach: Since you have concepts like polymorphism in object oriented systems you can follow a uniform approach throughout the system. What does this means is same function names can be used for similar operations on different data types etc. By using the concept of operator overloading you apply the above mentioned idea to operators also. So the uniformity of process can be established. From the external prospective the same function<br />
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name and same operator would be used but internally they may have different implementations. The same is not possible in traditional systems. The above mentioned are the list of advantages that an object oriented system gives you over the traditional systems. From both the user and developer views object oriented systems are far better than the traditional systems 9.7 Issues with Object oriented systems Though object oriented systems provide all the above mentioned advantages, there are certain issues which need to be addressed with object oriented systems. This section would provide you a view on those issues which have to be looked up in the object oriented design and development process. <br />
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While defining members of an object proper care has to be given in the access modifiers associated with members. If a member is assigned an improper access modifier then it would seriously block the process of dataflow across the system. This may be lead to unwanted complications.<br />
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If the relationships among the classes are not identified properly this may lead to performance degradation. If the relationships are not identified properly then the concept of inheritance cannot be used to the optimal level. This would certainly reduce the advantage that we specified in the “reusability” section.<br />
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During the process of making the code simpler, the actual objective of the application should not be sacrificed.<br />
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Unnecessary usage of concepts like runtime polymorphism may be lead to unwanted complexities in your system. So their usage has to be proper.<br />
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While practicing object oriented approach it has been stated already that OOPs can follow framework approach. (Generally these frameworks would be created by programmers different from the actual programmers who are creating the final system). So if there is a flaw in the underlying framework it would become very difficult to rectify those errors because whole system is based on that framework.<br />
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The concept of multiple inheritance associated with object oriented systems may lead to certain problems. In the case of multiple inheritance a class would have been derived from more than one base class. If both the bases classes has same member then it can create unwanted results in the derived class. Because of this factor object oriented programming languages like Java do not support the concept of multiple inheritance directly. (But a java programmer can achieve the same result with the usage of ideas like “interface” etc). It is now generally advised to use multiple inheritance in only those places where there exist no other alternative way of doing the same.<br />
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Choice of a proper object oriented language is also an important factor to be considered. For example if the development is for a standalone application then languages like C++ can be selected. If the target application is web oriented then languages like Java, PHP etc can be selected. The level of object oriented concepts support may vary from language to language. This factor should also be considered. Because if your target application requires a particular object oriented concept at multiple places then the language selected has to support that feature strongly. For example in the case of object based languages like Visual Basic there is no idea of inheritance. If your design requires inheritance<br />
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then the choice of Visual Basic as the development language may lead to serious problems. A good object oriented language selection would definitely make your development process easier and smoother. So this selection of language should also be given proper importance. From all the above mentioned points it can be concluded that if object oriented systems are not designed by properly utilizing the concepts provided, it may be lead to system with lesser performance and increased complexity. Summary <br />
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Simula is the first object oriented language.<br />
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Smalltalk is the language developed next to Simula. It has more object oriented features than Simula.<br />
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Most of the languages today have support for object oriented concepts.<br />
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Object based languages has support for few of the object oriented concepts but not all. For example visual basic (up to 6.0) is considered as object based language.<br />
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Object oriented systems model the real world problem. So it becomes easy to solve the problem.<br />
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A class is a template for creation of objects.<br />
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An object is an instance of a class.<br />
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Object has data members and member functions.<br />
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The access to the member can be controlled through access modifiers.<br />
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Inheritance is the process using the existing class functionality into new classes. There are many types of inheritance like simple, multilevel, multiple etc.<br />
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There are many polymorphism concepts like function overloading, operator overloading etc.<br />
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Constructors are the specialized functions which would be called automatically when an object is created.<br />
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Abstract class is one to which objects are not created directly.<br />
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Static members are common across all the objects created. Static members can be accessed with class name itself.<br />
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There exist many access modifiers like public, private and protected.<br />
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The object oriented systems provide advantages like abstraction, extensibility etc.<br />
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Object oriented database management systems apply the OOP concepts to database management systems. Self Assessment Questions Part I (Multiple Choice Questions)<br />
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Which of the following is not an object oriented language <br />
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C++<br />
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Java<br />
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ForTran<br />
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All of the above<br />
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None of the above<br />
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Constructors <br />
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have same name as class name<br />
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Would be automatically called during object creation.<br />
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Can be overloaded<br />
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All of the above<br />
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None of the above<br />
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Which of following provides reusability <br />
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inheritance<br />
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abstraction<br />
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access modifiers<br />
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All of the above<br />
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None of the above<br />
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The inheritance where more than one base class is there <br />
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Single<br />
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Multiple<br />
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Hierarchical<br />
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All of the above<br />
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None of the above<br />
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Which of the following is/are polymorphism concepts <br />
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operator overloading<br />
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function overloaded<br />
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virtual function<br />
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all of the above<br />
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none of the above<br />
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Abstract class <br />
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can be used to create objects<br />
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cannot be used to create objects<br />
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Is not supported in OOP.<br />
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All of the above<br />
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none of the above<br />
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The members which can be accessed directly with class name is/are <br />
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private members<br />
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public members<br />
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static members<br />
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all of the above<br />
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none of the above<br />
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Object oriented system advantage(s) include <br />
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reusability<br />
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extensibility<br />
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abstraction<br />
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all of the above<br />
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none of the above<br />
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The concept that is used to free up memory from unwanted resources is/are called<br />
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destructors<br />
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constructors<br />
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operators<br />
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all of the above<br />
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none of the above<br />
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Which of the following is the oldest object orientated programming language <br />
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Simula<br />
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Smalltalk<br />
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C++<br />
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all of the above<br />
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none of the above Part II (Short Questions)<br />
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Define object.<br />
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What is inheritance?<br />
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Write short notes on constructors?<br />
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Write short notes on function overloading.<br />
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Explain static members.<br />
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What is multiple inheritance?<br />
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Explain any two advantages of object oriented programming.<br />
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List out any four object oriented programming languages. Part III (Long Answer Questions)<br />
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Explain various types of inheritance in detail.<br />
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Explain the advantages of object oriented systems. Answer Key Part I<br />
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1. c<br />
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2. d<br />
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3. a<br />
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4. b<br />
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5. d<br />
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6. b<br />
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7. c<br />
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8. d<br />
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9. a<br />
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10. a Part II<br />
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An object is an instance of a class. The class acts as a model using which the objects are created.<br />
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Inheritance is the most important feature of object oriented systems. Inheritance facilitates the reusability concept. Inheritance is the process of reusing an existing class with additional features through a derived class.<br />
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Constructor is a member function which would be called automatically when an object is created. Constructors are primarily used for initialization process. Constructors generally have the name of the class.<br />
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Function overloading is using a single function name for more than one purposes. Multiple version of a function would be written. Each function would differ in the count and type of parameters.<br />
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A static member function is common to all the objects. These members can be accessed directly by using the class name. One generic usage of static function is to use them as counters.<br />
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When a class is derived from more than one base class it is called multiple inheritance.<br />
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Reusability is one of the prime advantages of object oriented programming. Abstraction is another advantage of Object oriented systems. In abstraction internal working of an object is hidden. Simply the functions can be invoked and the corresponding action would be carried out.<br />
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There exist may object oriented programming languages. Some of them are C++, Java, Smalltalk, PHP etc.<br />
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Lesson 10: Enterprise Computing & Mobile Computing Introduction <br />
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The term enterprise refers to larger organization.<br />
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The computing needs in an organization which is huge would be certainly more than the requirements of a normal sized organization.<br />
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This lesson would elaborate on the topic of enterprise computing including description of its various components, their requirements, advantages, financial implications etc.<br />
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Objectives <br />
<br />
Introducing Enterprise resource planning.<br />
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Explaining various steps involved in ERP.<br />
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Listing out the advantages and disadvantage of ERP.<br />
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Introducing mobile computing.<br />
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Explaining the components of mobile network.<br />
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Introducing the technologies associated with mobile computing.<br />
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Explaining various advantages and disadvantages of mobile computing.<br />
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10.1 Enterprise Resource Planning Enterprise Resource Planning (ERP) is one of the key terms in the business paradigm. ERP refers to the system where an integrated approach is followed among all the departments of the organization. In other words ERP uses a single large database to hold the data of all the departments of the organization. ERP can be defined as a single largest software application which caters the needs of all the departments of the organization. By this we mean that people in finance department and people in production department would be using the<br />
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same software but there would be access rights (i.e., only authorized users would be allowed to access critical portions of the software). Though ERP software has its scope across all the departments of an organization it is not always mandatory that ERP should cover all the departments. Even if one or two departments are missed then also the software can be termed as Enterprise resource planning.<br />
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10.1.1 What does ERP means? Let us look at the term ERP itself much closer. The “E” stands for Enterprise which has been already indicated as a larger organization. The “R” stands for resources of the organization. Normally resource includes components like man, machine and materials. In other words “R” refers to all the properties of the organization starting from a low cost device to costliest equipment of the organization. “P” stands for planning. Planning is the usage of above mentioned resources in a better way. So in total ERP can be considered as a system which enables the organization to use all of its resource in the optimal manner.<br />
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10.1.2 ERP and various departments of the organization As it has been stated earlier, ERP covers most of the departments of the enterprise. Now the scope of the ERP system would be described. The following is a list of departments which would get benefited from ERP. <br />
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Production department: The production department would have various functions which are as listed below:<br />
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<br />
Workflow management<br />
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<br />
Scheduling of Production<br />
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<br />
Quality control etc<br />
<br />
Human Resources Department: Human resources (HR) department would have functions as listed below:<br />
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Staffing (recruitment)<br />
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<br />
Pay bill<br />
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Employee benefits management<br />
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<br />
<br />
Controlling the regularity of employee presence in the organization<br />
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<br />
Other tasks like fixing up tour schedules incase of onsite work etc.<br />
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<br />
Customer Relationship management: CRM department plays a critical role because it is in direct contact with the customers of the organization who are the backbone of organization. It has operations like:<br />
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<br />
<br />
<br />
<br />
Quality of service ensuring<br />
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<br />
Keeping track of customer information.<br />
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Finance Department: The revenue of the organization is taken care by the finance department. It includes operations like <br />
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Cash management<br />
<br />
<br />
<br />
Assets management<br />
<br />
<br />
<br />
Account payable and account receivable etc<br />
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ERP would consist of modules for all of the above mentioned tasks. If the ERP is not there then these departments has to use to individual software which would again use separate databases. So it would become very tedious to fetch the data which is required without much delay.<br />
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10.1.3 Why ERP? When the standalone software itself is satisfying the need of the department why ERP is required is another interesting question to consider. The following facts may be provided as answer to this question: <br />
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Top level view of data: The top level management requires a bird's eye view of data i.e. every unit in the organization may have different ways of interpreting and presenting the data which would become very confusing<br />
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and less useful for the organization. To provide that unified top level view of data you require a system which has its scope in the entire above mentioned departments. ERP is definitely such a system. So this becomes the primary reason for implementation of ERP. <br />
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Better customer satisfaction: By implementing ERP the customers‟ requirements can be satisfied in an effective manner. This becomes possible because by the implementation of ERP there is seamless integration of data. So the customer information can be easily tracked.<br />
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<br />
<br />
Better employee satisfaction: At times it becomes important to concentrate on employee satisfaction also. ERP helps to this by providing the up-todate information regarding employee's needs to the Human resource team. By having this information employee's can be given good benefits.<br />
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<br />
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Better Control over inventory: Since you have collaborative information available by the implementation of ERP there is no need to overflow the warehouse with many items because you now have the real time update of inventory required. So the inventory can be managed in a better way.<br />
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<br />
Analysis of pattern across data: Because of the integration between data of various departments it becomes easy to analyse various patterns among those data. By finding out those patterns decision can be taken to either reduce the cost or providing better service to the customers.<br />
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10.1.4 What ERP is not? Many times the ERP software is confused with back office software. But ERP is not back office software. Typical back office software would not have any communication with the end-users or customers. But the ERP has modules where it deals with customers, like Customer Relationship Management (CRM) and Supplier Relationship Management (SRM) etc. So ERP is not back office software (but it includes the functionality of back office software also).<br />
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Generally ERP software is not developed by in-house experts. Well defined ERP software would be purchased and during the implementation it can be customized to satisfy the needs of the organization.<br />
<br />
10.1.5 ERP is costlier One of the major facts the organizations consider while implementing the ERP software is the cost associated with it. The cost would include following components: <br />
<br />
Cost of the original ERP software<br />
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<br />
<br />
Cost of the hardware required to install the ERP<br />
<br />
<br />
<br />
Cost incurred due to expert consultancies<br />
<br />
<br />
<br />
Cost to train the internal employees to cope up with the newly implemented ERP software. The tangible financial benefits that the organization would get will<br />
<br />
require some time delay i.e., immediately after the implementation of ERP you cannot expect tangible financial benefits. The cost incurred due to customization, cost of testing should also be taken into consideration. Apart from all the above mentioned cost there is one more important component called “data migration”. The organization would have its operational data. Those data would be in the individual software. So it becomes ultimately necessary to migrate all these data from the standalone software to ERP system. To perform this migration tasks specialized data migration tools would be used. During the migration of data itself you have to consider various factors. Some of them are listed below: <br />
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Deciding the tools for migration<br />
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Deciding which data to migrate and which not<br />
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<br />
Identifying the correlation between the data model of existing systems and the newly implemented system.<br />
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<br />
<br />
A clear decision about level and mode of backup should be decided.<br />
<br />
All the above mentioned tasks may be directly equated with cost. The entire above mentioned steps would have the operational cost associated with it. The total cost of an ERP implementation would include all the above mentioned factors. So before deciding to go for the ERP system the organization has to clearly think about the merits and demerits in terms of financial implications as well as workflow modifications. In one word you can state that ERP software are costlier in nature at the same time they are effective as well.<br />
<br />
10.1.6 ERP activities or steps Once the organization has decided to go for the ERP software it has to go through the following list of activities: <br />
<br />
Identifying the right product: The very first decision that the organization has to take is the selection of best suited ERP product for that organization. There exist many companies which produces ERP software today. For example, PeopleSoft, Oracle etc. The selection of correct product would play a major role in deciding the success or failure of that particular ERP implementation.<br />
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<br />
Installation of optimal hardware: Not only the ERP software but any software would function smoothly if and only if there is the optimal hardware. Even the best software can produce worst results if they are implemented on improper hardware.<br />
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<br />
<br />
Customization: Since ERP is the software that touches most of the departments, it has to be customized for organization's need. The level of customization has to be perfectly planned. There is an idea with ERP software which is called “Best practices” i.e. which are well tested methods of works. So you have to decide where the organization is<br />
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<br />
going to adopt the ERP's way and where to customize the ERP according to organization's workflow. This decision would play a vital role in effectiveness of that ERP implementation. <br />
<br />
Migration of data: As stated earlier the operational data that the organization is currently using with its standalone software has to be migrated to the ERP. These data cannot be simply copied and pasted because the data model of their traditional software and ERP would be certainly different. So proper migration tools has to be employed to carry out this data migration task. The backup of old data may also become useful at later point. So it becomes necessary to backup the critical data to cope up with any flaws at a later stage.<br />
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<br />
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Testing: Once the customization procedure is over the ERP software has to be tested for correctness. This testing has to be conducted in a rigorous way because once the ERP goes to production with critical bugs it can have serious impacts on organization's performance. So the testing has to be carried out properly.<br />
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<br />
<br />
Training of internal staff: In order to work with the ERP software the employee's of the organization has to undergo proper training procedure. Because it is those employees who are going to use the ERP software on a day-to-day basis. They have to be made to feel comfortable with the ERP software. (Initially there can be a level of opposition from the employees because the ERP is going to replace the tools in which they would have got expertise). It becomes the responsibility of the training team to make the internal staff to feel comfortable with the ERP software.<br />
<br />
<br />
<br />
Maintenance: Once the ERP goes to production there can be needs arising at a later time for smaller changes. These genuine needs have to be incorporated in to the ERP software so that it produces the best results.<br />
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<br />
Once the above mentioned activities are performed then (up to “training of internal staff”) then ERP can be applied for production purpose (i.e., for actual use). To make the ERP software more productive there can be one more testing step after customization before the data migration. At this step the correctness of the customization can be tested. The later testing i.e., after the data migration it would be tested with original data from the standalone software. This testing can identify more bugs because there can be certain bugs which may be dependent on certain specific data patterns which can be missed during the previous testing with test-data.<br />
<br />
10.1.7 Extending ERP If the ERP system has to be used by users outside organization like customers then ERP software has to be made in a manner which would make the end-users feel comfortable with ERP. The internal staffs are given additional training so they can understand the technical jargons used with ERP. But the customers may not be aware of these technical jargons. So it has to be made simple. If the ERP application has got interface where the customers would directly transact with it, then it would be on the Web platform. Once a part of ERP comes to web then you have to consider the following facts: <br />
<br />
Security: Since the World Wide Web can lead to potential hackers landing on your system, they have to be much secure.<br />
<br />
<br />
<br />
Nonstop functionality: Once the web interface is there the system has to be up and running for most of the time. If there is schedules for upgrading your ERP system then proper measures has to be taken so that the end users would not get affected drastically.<br />
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<br />
But these features would make your ERP system more powerful. But these components where customers have direct transaction through web have to be made secure at the same time easier to use. If the organization is of global scale then the concepts of internationalization should also be taken into consideration because customers can be from any part of the globe and they feel very comfortable if the interface is supporting their own regional settings. These features can increase the customer size of the organization because now you are attracting customers from every part of the globe. (These features may not be required to organization where its operational boundary is restricted to lesser geographical boundary.<br />
<br />
10.1.8 ERP critical factors During implementation (and even after implementation) certain points have to be given more attention. Some of them are listed below: <br />
<br />
By the implementation of ERP, employees in the organization lose their expertise that they have developed over a period of time with the existing tools. So there would some strong protest from portions of employees. The concerns raised by the employees should not be neglected in total. Where ever the points raised by them are valid they have to be incorporated.<br />
<br />
<br />
<br />
The interfaces and functionalities ERP provide should be far better than the functionalities and interfaces of traditional systems that the organization is already using. If the ERP system is providing lengthier procedures to perform tasks which can be performed easily in their legacy software then there would be strong objections. So the effectiveness and easiness of using ERP should be given higher precedence.<br />
<br />
- 258 -<br />
<br />
<br />
<br />
When a newer version of ERP software gets released the organization may wish to update to the current version. If the current implementation has been done with lots of customization then this would not be an easier exercise. In such a stage the benefits that the organization gets by the newer version has to be compared with the effort that has to be put, to adopt the newer version for the organization.<br />
<br />
10.1.9 ERP advantages and disadvantages Let us explore the advantages and disadvantages of ERP. To start with advantages are given in the following list. <br />
<br />
High-level view of data is possible.<br />
<br />
<br />
<br />
Uniform interfaces and procedures would be adopted by all the departments where the ERP system is implemented.<br />
<br />
<br />
<br />
ERP systems would improve the customer satisfaction since all the departments would get the real time update of data. This facilitates quicker actions for customer queries.<br />
<br />
<br />
<br />
ERP systems would provide you higher levels of security comparing to the standalone systems. This would reduce the unauthorized access of data to a greater extent.<br />
<br />
<br />
<br />
Finer levels of access control can be implemented. This would clearly define the boundaries of actions that an employee can perform. This is an additional level of security.<br />
<br />
Though ERP provides all the above mentioned advantages there exist disadvantages also. They are as listed below: <br />
<br />
ERP software is costlier in nature.<br />
<br />
<br />
<br />
Though the ERP software can be customized for organization's need the customization cannot be to maximum extent. So at places the<br />
<br />
- 259 -<br />
<br />
organization has to adopt the work procedure provided by the ERP software. <br />
<br />
Major portions of employees lose their expertise gained over a period time with the existing tools.<br />
<br />
<br />
<br />
ERP<br />
<br />
software<br />
<br />
becomes<br />
<br />
too<br />
<br />
much<br />
<br />
complicated<br />
<br />
at<br />
<br />
many<br />
<br />
implementations. So it would become hard for the internal staff to understand it completely during the initial stages. <br />
<br />
The implementation schedule may become longer due to the levels of customization required by the organization. This would delay the production use of ERP in that organization.<br />
<br />
<br />
<br />
ERP implementations can become rigid so it would it make it hard for further modifications.<br />
<br />
An ERP system would treat the whole organization as a single entity. So it standardizes the operations across the organization. If the organization is big and strong enough to balance the expenses incurred during ERP implementation then ERP is certainly a powerful tool for the organization.<br />
<br />
10.2 Mobile Computing The desktop computers are becoming less popular nowadays. In place of desktop computers people want to use laptop computers and similar technologies. The primary reason for this shift is the ability to use computer on the move. Simply having a computer on the move many not be able to satisfy your need. Another important thing that you need is the network connectivity. Without network connectivity the productive use of the computer would become lesser. So it becomes ultimately necessary that network connectivity should be there needed on the move.<br />
<br />
- 260 -<br />
<br />
Mobile computing is the ability to use and exchange information between devices on the move i.e. without a physical connection because physical connection is not possible during the move. This section would elaborate on various mobile computing concepts and its advantages, challenges. In the network paradigm there exist two types of communications. They are <br />
<br />
Wired Communication<br />
<br />
<br />
<br />
Wireless Communication<br />
<br />
In the case of wired communication a physical communication would be established between the devices communicating with each other. Mobile computing needs the wireless communication techniques. There exist various techniques to perform wireless computing. Some of them are as follows: <br />
<br />
Infrared<br />
<br />
<br />
<br />
Bluetooth<br />
<br />
<br />
<br />
Wi-Fi<br />
<br />
<br />
<br />
Microwave based communication.<br />
<br />
<br />
<br />
Satellite communications.<br />
<br />
In the above list the first three techniques can be applied only in a shorter distance. But the mobile computing would require a communication methodology that can cover a larger area. So the last two techniques from the above list i.e., microwave based communication and satellite communication can be used for longer distance communication. Among these two techniques satellite communication can be used to cover very large areas. So in case where the connectivity is required at a global scale the satellite communication mode would be very much useful.<br />
<br />
- 261 -<br />
<br />
The effectiveness of the mobile computing requires a very good network that supports it. So the mode of communication plays an important role here in mobile computing.<br />
<br />
10.2.1 Major components Two major components of mobile computing are as listed below: <br />
<br />
Mobile devices<br />
<br />
<br />
<br />
Wireless network<br />
<br />
10.2.1.1 Mobile devices As stated in the beginning mobile computing requires devices which can be used on the move. These devices range from laptop, PDA, Mobile phones etc. The mobile devices should have ports through which it can access the network. Mobile devices are operated on a battery power. Most of the mobile devices would have two modes of power supply i.e., connecting it to the main power supply and operating them using battery power. Normally the batteries used with mobile devices are rechargeable in nature. They should be recharged at regular interval so that the life time of these batteries would be optimal. In combination with mobile devices there exist many types of software. For example there is a version of windows specifically available for mobile devices. One of the popular operating systems used with mobile phones is the Symbian operating system. The software designed for mobile devices has certain special characteristics. They are listed below: <br />
<br />
The file size of these applications should be comparatively lesser.<br />
<br />
- 262 -<br />
<br />
<br />
<br />
These applications have to utilize memory very much effectively because mobile devices generally would have very less amount of memory.<br />
<br />
<br />
<br />
The display associated with mobile devices would be lesser in size. So the user interface has to be designed in a way such that it can be used effectively in the smaller available area.<br />
<br />
There exist software versions specific to mobile devices. For example in the case of Opera web browser there is a special version called “Opera Mini” which is specific to mobile devices. 10.2.1.2 Wireless networks The techniques associated with wireless networks are as illustrated in previous sections. There are certain special protocols associated with mobile computing. One of the popular protocols is the WAP. It stands for Wireless Application Protocol. When you access internet through mobile phones this wireless application protocol would be very much useful.<br />
<br />
10.2.2 Cellular network The most popular network among the general public today is the cellular networks. This cellular network is the backbone of all the mobile phones today. The following components are involved in a cellular network. <br />
<br />
Base stations: Each base station would cover certain area. These base stations are transceivers. The base stations would be located in places decided by the network administrator based on various factors.<br />
<br />
<br />
<br />
Cell: The coverage area would be divided in to small chunks called cells.<br />
<br />
- 263 -<br />
<br />
<br />
<br />
Area: Collection of cells is called an area. These cells would be adjacent in nature.<br />
<br />
<br />
<br />
Mobile Switching Centre (MSC): The role of Mobile switching centre is to route the calls from the caller to sender.<br />
<br />
<br />
<br />
From this mobile network you would be able to access the public switched telephone network (PSTN).<br />
<br />
<br />
<br />
There is a phenomenon called “hand over” by which the connection is retained though the communicating devices are moving from one cell to another.<br />
<br />
10.2.2.1 Technologies associated with Mobile networks There exist many different technologies associated with mobile networks. Some of them are as listed below: <br />
<br />
Time Division Multiple Access (TDMA)<br />
<br />
<br />
<br />
Code Division Multiple Access (CDMA)<br />
<br />
<br />
<br />
Global System for Mobile (GSM)<br />
<br />
<br />
<br />
Frequency division multiple Access (FDMA)<br />
<br />
The complete description of all the above technique would be out of scope of our current text. 10.2.2 Advantages and disadvantages of Mobile computing There exist many advantages of mobile computing as listed below: <br />
<br />
Communication can be established independent of the location.<br />
<br />
<br />
<br />
Mobile devices generally provides integrated services<br />
<br />
Some of the disadvantages of mobile computing <br />
<br />
The battery power used with mobile devices has to be recharged at regularly intervals.<br />
<br />
<br />
<br />
Security associated with mobile network is a serious problem.<br />
<br />
- 264 -<br />
<br />
<br />
<br />
The network coverage is another issue with mobile computing.<br />
<br />
Summary <br />
<br />
ERP stands for Enterprise resource planning.<br />
<br />
<br />
<br />
ERP would cater the needs of all the departments (majority of) of the organization: Production, Finance, Human Resource Management etc.<br />
<br />
<br />
<br />
ERP software is costlier in general.<br />
<br />
<br />
<br />
ERP implementation involves various steps like choosing right vendor, selection of proper hardware, testing etc.<br />
<br />
<br />
<br />
By the implementation of ERP software the roles of people in the organization would change. So proper training has to be given.<br />
<br />
<br />
<br />
There are many advantages of ERP like high level view of data, extended security etc. Proper access controls can be established through ERP.<br />
<br />
<br />
<br />
ERP also possess few disadvantages like costlier, the problem of changing the routine activities of the employees with different procedures etc.<br />
<br />
<br />
<br />
ERP is not synonymous to back office software. ERP has larger scope than the back office software.<br />
<br />
<br />
<br />
Mobile computing refers to phenomenon of accessing network and computing facilities “on the move”.<br />
<br />
<br />
<br />
Mobile computing requires mobile devices, wire-less networks.<br />
<br />
<br />
<br />
There exist many cellular network technologies like GSM, CDMA etc.<br />
<br />
<br />
<br />
Mobile computing gives you the advantage of accessing the services from any place where the network coverage is there.<br />
<br />
<br />
<br />
Mobile devices require battery power. The battery power cannot prolong beyond particular time boundaries. So they have to recharge in proper intervals of time.<br />
<br />
- 265 -<br />
<br />
Self Assessment Questions Part I (Multiple Choice Questions) <br />
<br />
<br />
<br />
<br />
<br />
ERP stands for <br />
<br />
Extended Reliable Performance<br />
<br />
<br />
<br />
Enterprise Resource Planning<br />
<br />
<br />
<br />
Easier Recoverable Programs<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
ERP becomes costlier because of <br />
<br />
Cost of hardware<br />
<br />
<br />
<br />
Cost of training<br />
<br />
<br />
<br />
Cost of software<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
ERP software <br />
<br />
<br />
<br />
Covers many departments Costlier in nature<br />
<br />
<br />
<br />
Customizable<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
Advantages of ERP include <br />
<br />
improved security<br />
<br />
<br />
<br />
slower execution<br />
<br />
<br />
<br />
non extensibility<br />
<br />
<br />
<br />
All of the above<br />
<br />
- 266 -<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
None of the above<br />
<br />
Wi-Fi stands for <br />
<br />
Wireless Fidelity<br />
<br />
<br />
<br />
Wired Findings<br />
<br />
<br />
<br />
Windows Findings<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
TDMA is <br />
<br />
Time Division Multiple Access<br />
<br />
<br />
<br />
Total Data Mode Access<br />
<br />
<br />
<br />
Time Division Major Access<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
Mobile computing requires <br />
<br />
Hand-held devices<br />
<br />
<br />
<br />
Wireless networks<br />
<br />
<br />
<br />
Battery power<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
In cellular Networks an area is <br />
<br />
A collection of points<br />
<br />
<br />
<br />
A collection of cells<br />
<br />
<br />
<br />
A collection of devices<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
- 267 -<br />
<br />
<br />
<br />
<br />
<br />
In cellular network, MSC stands for <br />
<br />
Mobile Switching Centre<br />
<br />
<br />
<br />
Mobile Sending Centre<br />
<br />
<br />
<br />
Mobile Software Centre<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above<br />
<br />
Which of the following is/are mobile web browser(s) <br />
<br />
mobile net<br />
<br />
<br />
<br />
mobile com<br />
<br />
<br />
<br />
opera mini<br />
<br />
<br />
<br />
All of the above<br />
<br />
<br />
<br />
None of the above Part II (Short Questions)<br />
<br />
<br />
<br />
Write short notes on ERP.<br />
<br />
<br />
<br />
Why ERP is costlier?<br />
<br />
<br />
<br />
What do you mean by “data migration”?<br />
<br />
<br />
<br />
Write short notes on ERP advantages.<br />
<br />
<br />
<br />
List out different technologies involved in mobile networks.<br />
<br />
<br />
<br />
List out the disadvantages of mobile networks. Part III (Long Answer)<br />
<br />
<br />
<br />
Explain various steps in implementation of ERP in detail.<br />
<br />
<br />
<br />
Explain the advantages and disadvantages of ERP.<br />
<br />
<br />
<br />
Elaborate about Mobile Computing.<br />
<br />
- 268 -<br />
<br />
Answer Key Part I 1. b<br />
<br />
2. d<br />
<br />
3. d<br />
<br />
4. a<br />
<br />
5. a<br />
<br />
6. a<br />
<br />
7. d<br />
<br />
8. b<br />
<br />
9. a<br />
<br />
10. c Part II<br />
<br />
<br />
<br />
ERP stands for Enterprise Resource Planning. ERP covers all the departments of an organization. ERP maintains single database for storing data about all the departments.<br />
<br />
<br />
<br />
<br />
<br />
ERP is costlier is because of various factors <br />
<br />
The cost of software<br />
<br />
<br />
<br />
Cost of hardware<br />
<br />
<br />
<br />
Cost of customization<br />
<br />
<br />
<br />
Cost of training.<br />
<br />
Data migration is the process of transferring data from existing system in to ERP. The data models of both the systems would be different. So specialized tools have to be developed for this migration process.<br />
<br />
<br />
<br />
ERP gives various advantages like high level view of data, more security, finer access controls, customization etc.<br />
<br />
<br />
<br />
Various technologies used in mobile networks are GSM, TDMA, and CDMA etc.<br />
<br />
<br />
<br />
Mobile computing has disadvantages like dependence of battery power, network coverage issues etc.<br />
<br />
- 269 -<br />
<br />
List of Figures<br />
<br />
- 270 -<br />
<br />
Figure 3.1: Input Device Categories<br />
<br />
Figure 3.2 Output Device Categories<br />
<br />
Figure 3.3: Display Card as Interface between CPU and Display device<br />
<br />
- 271 -<br />
<br />
Figure 3.4: Classification of printers<br />
<br />
Figure 4.1: Bus topology<br />
<br />
Figure 4.2: Star topology<br />
<br />
- 272 -<br />
<br />
Figure 4.3 : Ring (single) topology<br />
<br />
Figure 4.4 : Ring (Dual) topology<br />
<br />
- 273 -<br />
<br />
Figure 4.5 : Mesh topology with 3 nodes<br />
<br />
Fig 5.1: Operating System as an interface between user and computer<br />
<br />
- 274 -<br />
<br />
Fig 6.1: Role of Assembler<br />
<br />
Fig 6.2 : Role of compiler<br />
<br />
Fig 6.3 : Role of interpreter<br />
<br />
- 275 -<br />
<br />
Fig 6.4 : Spreadsheet (Microsoft Excel)<br />
<br />
Fig 6.5 : Spread sheet with a formula in the cell<br />
<br />
- 276 -<br />
<br />
Fig 6.6 : Spreadsheet showing the result of the formula in the cell<br />
<br />
Fig 6.7 conditional formatting<br />
<br />
- 277 -<br />
<br />
Fig 6.8 : Filtering applied to the spreadsheet<br />
<br />
Fig 6.9: Bar chart created using spreadsheet application<br />
<br />
- 278 -<br />
<br />
Fig 6.10: Pie chart using spreadsheet application<br />
<br />
Figure 6.11: Initial Screen in PowerPoint Presentation<br />
<br />
- 279 -<br />
<br />
Figure 6.12 : Procedure to insert a new Slide<br />
<br />
Figure 6.13 : Slide Sorter View<br />
<br />
- 280 -<br />
<br />
Figure 6.14 : Predefined Designs for Slides<br />
<br />
Figure 6.15: Adding Animation to your slides<br />
<br />
- 281 -<br />
<br />
Figure 6.16: Applying animation to objects<br />
<br />
Figure 6.17 : Outline View in Presentation<br />
<br />
- 282 -<br />
<br />
Figure 6.18: Printer Options in presentation tools<br />
<br />
Figure 6.19 : Grids for Proper Alignments<br />
<br />
- 283 -<br />
<br />
Figure 7.1: Modem connection computers and Telephone networks<br />
<br />
Figure 7.2: DNS between URL and IP address<br />
<br />
- 284 -<br />
<br />
Figure 7.3 Simple HTML listing with its output<br />
<br />
Figure 7.4 Title Tag<br />
<br />
- 285 -<br />
<br />
Figure 7.5 Paragraph Tag<br />
<br />
Fig 7.6 Table Tag<br />
<br />
- 286 -<br />
<br />
Fig 8.1: various content forms of multimedia<br />
<br />
Figure 9.1 Simple Inheritance<br />
<br />
- 287 -<br />
<br />
Figure 9.2: Multilevel Inheritance<br />
<br />
Figure 9.3: Hierarchical Inheritance<br />
<br />
Figure 9.4: Multiple Inheritance<br />
<br />
- 288 -<br />
<br />
Figure 9.5: Hybrid Inheritance<br />
<br />
- 289 -<br />
<br />
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