CBSE Notes for Class 9 Foundation of Information Technology – Computer System
COMPUTER SYSTEM
Some decades ago, computers were known to a common man as simply a fast calculating device. But now with Information Technology (IT) revolution, computers have entered into each and every field of life. People in every walk of life now understand that the knowledge of computers is very essential if they need to keep pace with the information and technology in society. Computers have relieved us from the boring and tiring tasks like copying, comparing, choosing, checking etc. and now human time and labour can be used much more effectively. Let us quickly revise the definition of a computer.
CHARACTERISTICS OF COMPUTERS
What has made computers so popular and essential that we feel their need in any task we do? The answer lies in the following:
1. Speed: Computers work at an enormous speed, so much so that while talking about computer speed, minutes and seconds seem to be a lifetime because time taken by a computer to execute an instruction ranges from picoseconds to nanoseconds to microseconds.
| Unit of Time | Part of a Second |
| Millisecond (ms) | One thousandth (1/103) |
| Microsecond (ms) | One millionth (1/106) |
| Nanosecond (ns) | One billionth (1/109) |
| Picosecond (ps) | One trillionth (1/1012) |
Usually the speed of computer is measured in MIPS (million instructions per second). So if we say that the speed of a computer is 60 mips, it means that the computer can execute 60 million instructions in one second.
2. Accuracy: Another very important characteristic of computers is the accuracy of results. It can give a result of very complicated calculations accurate upto say 10 decimal places (depending upon the type of computer) within fraction of a second. But yes, a computer follows the principle of GIGO i.e., Garbage in Garbage out. If the computer is given correct data and instructions, then only it will return an accurate result.
3. Diligence: Imagine doing the same work a number of times. You will definitely feel tired or bored. But a computer neither gets tired nor bored doing the same task as many number of times as you want.
4. Versatility: Computers are capable of doing varied types of jobs. For example, on your personal computer you can play games, do mathematical calculations, surf the Internet, send e-mail, draw pictures etc.
5. Enormous Storage Capacity: Computers can store a large amount of information and data in their memory. The data can be stored on external storage devices like CDs (Compact Disks) and Pen drives. This way the data can be taken anywhere. Data from the computer’s memory and from the storage devices can be retrieved accurately anywhere and at anytime. This has also made the workplaces free of the junk of loads of files with old records.
BASIC OPERATIONS OF COMPUTERS
The most basic operations which a computer can perform at a primary level are:
1. Input/Output Operation: To understand the input/output operations, let us first study the difference between Data and Information.
Input is the data and the instructions to be applied on the data which we give to the computer. Input operation can be performed using various input devices such as keyboard, mouse, light pen, scanner etc. Computer generates the output by applying the instructions on the data. We can receive this output by using various output devices like printers, VDU (Visual Display Unit), graphic plotters, COM (Computer Output on Microfilm) etc. We shall study the input/output devices in detail in the next chapter.
2. Text Manipulation: The input given to the computer can be
(i) Numeric i.e., a combination of digits from 0 to 9.
(ii) Alphabetic i.e., a combination of alphabets from A-Z, ‘a’ to ‘z’ and special characters such as (, ), *, !, { etc.
(iii) Alphanumeric i.e., a combination of alphabetic and numeric data.
3. Logical Operations: A logical expression is that statement which does not show a numeric result but gives a result in the form of True/False or Yes/No. The logical operators are OR, AND, NOT
If (p OR q) Yes print “Admission granted” else print “Admission not granted”
Matter will be printed according to whether p is Yes or q is Yes.
4. Mathematical Calculations: Various mathematical operations like addition (+), multiplication (*), subtraction (-) and division (/) can be performed by a computer on numeric data.
5. Summarizing Data: As computers work on enormous amount of data, understanding
the data by just viewing it is sometimes very difficult for us. Computers can represent the data in the form of pie charts, bar graphs, line graphs, tables and reports. This helps us in easier and quicker understanding of data.
6. Storage and Access: Any type of data can be stored by computers and any data can be accessed by it within a fraction of a second. Various storage devices like Magnetic tapes, disks, films etc. are used for this purpose. (Details are discussed in Chapter 3)
AREAS OF COMPUTER APPLICATION
1. Education: To make our next generation ready for a computer-dominated world, computers have been introduced in every school and college. A time has come when there can be classrooms without teachers. Each student can learn at his/her own pace and can spend as much time on a particular topic as he/ she wants. He/she can then evaluate himself/herself on the topic using on-line examination.
2. Medicine: Computers are acting as doctors in remote areas where medical experts or even doctors are not available. In hospitals, computers are being used to monitor patients. Many operations are being done by robots controlled by expert surgeons sitting far away from operation theatre.
3. Weather Forecasting: Supercomputers have proved to be of great help to meteorologists in forecasting the weather worldwide. This has helped in reducing human and animal casualties and damage to crops.
4. Quality Improvement: Computers help in designing high quality products. Computers Aided Design (CAD) software helps engineers to design machine parts on computers and study the effects of various stress factors on its various parts. This helps in creating the better design.
5. Better Service: Computers at railways and airline reservation counters have made the process of reservation/cancellation of tickets very easy and less tiresome. Now people do not have to stand in long queues for reservation of tickets at some restricted counters. Tickets can be reserved/cancelled for anywhere from anywhere. Nowadays one can sit at home and contact various travel agencies on internet and get a whole tour to any place booked including the railway/airline, hotel reservation. Computers in banks have improved their services tremendously. Introduction of credit cards and ATM (Automated Teller Machine) have resulted in easier shopping and drawing of money.
6. Better Management by Government: Computers have helped various departments of government in successful planning and control. For example, law enforcement, healthcare, land records and registration, billing, etc.
7. Data Management: In the departments like Income Tax and National Stock Exchange where everyday enormous amount of data has to be dealt with, computers have helped in replacing huge stacks of files by a few disks and drives.
8. Entertainment: Besides many interesting games which can be played on personal computers (PCs), computer graphics have brought a revolution in the cine world also. Movies like Jurassic Park and Godzilla have been made using computer graphics.
9. Information Access and Mailing: Internet has been the best gift of computers to our society. Any information about anything can be had anywhere in the world by just sitting in front of your computer, mobile phone or smart television and connecting to the internet. E-mail and chats on the internet have literally brought people of the world close. There are many more applications like Desk Top Publishing, Research, Defence, Space Travel etc. where also use of computers have brought a revolution.
So basically there remains hardly any sphere of life untouched by computers.
CONVERGENCE OF TECHNOLOGIES
Commonly referred to as the 3C’s, the convergence is basically of computer technology, telecommunication, networking and broadcasting technology and most important the multimedia technology.
Computers have become smaller in size, cheaper in price but advanced in technology and more powerful. The processor speed has increased, internal memory has increased and the versatility of computer has no bounds.
Communication channels have changed from co-axial cables to ethernet cables to optical fibres and now wireless networking. With the advent of Internet, the whole scenario has changed. Computers are no longer just processing devices. They are more of a data communication and information retrieval devices.
Various services like www, e-commerce, e-learning, e-mail, video conferencing, weather forcasting etc. which have benefited our lives in a great way are a result of convergence of technologies.
Convergence means integration and convergence of technologies and basically refers to integration of voice, video and data technologies. These technologies working on different platforms when interact with each other raises the performance.
Nowadays the term ICT (information and communication technology) is very commonly used. It refers to the union of communication system, audio-visual system and computer technology. So in a way convergence of technology and ICT are the same. Smart phones used today are the best example of convergence of technologies. Earlier telephone allowed just audio communication. But now with the invent of new technologies, a mobile phone is used for audio, video, data transfer, information retrieval using Internet, text mailing and messaging, playing device, camera, GPS (Global Positioning System) etc. Everyday a new technology is being used to add a new feature to the mobile phones.
The new technologies are not only offering us new features but are also allowing us to integrate the old technology to the new technology e.g., new software being developed are not restricted to the new version of operating systems or hardware requirement. They are developed in such a way that they can be executed on the old versions of operating systems and microprocessors e.g., a new application in the market will be welcomed if it can run on Windows 8, Windows 7 and Windows 98 as well.
Convergence of technologies has also lead to working together of several devices working on completely different technologies and in different environments. For example, a television set can be transformed into a gaming set for play station or into a computer screen for full screen viewing, a mobile phone can be used as a music system when attached to external speakers or can be used as a camera to record and play the videos at high resolution. So a mobile phone is a compact home theatre in itself.
Content Technology
Ever wondered how by just typing one or two words on the search tab, we get hundreds of websites related to our search. There is enormous information on the web which is generally referred to as content. This data has to be encoded, delivered, retrieved and managed. The content technology is the term used for the mechanism that helps in managing web content.
It includes markup languages, data formats, programming languages e.g., HTML, Javascript, PDF, Flash etc.