erUNIT 1 INTRODUCTION TO COMPUTERS
1.1 1.2 1.3 Introduction
Introduction to Computers
Why Computer? Evolution of Computers
1.3.1 The First Computer 1.3.2 Some Well Known Early Computers 1.3.3 Computer Generations
1.4 1.5 1.6 1.7 1.8 1.9
Components of a Computer Hardware vs Software System vs Applications Software Bits and Bytes Input and Output Devices RAM/ROM
1.10 Secondary Storage Devices 1.11 Summary 1.12 Answers to SAQs
This unit aims at introducing you to today’s most commonly used electronic device – the computer. The study of this unit will highlight the characteristics and evolution of computers. It will also help you to understand the basic terminology associated with computers.
After studying this unit, you should be able to • • • • • • • • • understand the basic characteristics of computers, understand how the computers evolved, understand the components that make up a computer, differentiate between hardware and software, differentiate between system and application software, understand the difference between bits and bytes, classify devices as input and output devices, differentiate between ROM and RAM, and appreciate the use of various secondary storage devices.
1.2 WHY COMPUTER?
The word ‘Computer’ literally means to ‘Compute’ or to ‘Calculate’. Stated simply, it is an electronic device, which processes information based on the instructions provided, to generate the desired output. It, therefore, requires two
types of input – raw data, and the set of instructions to process or act upon the data. This can schematically be shown in Figure 1.1. Data Process Instructions Input Output
Figure 1.1 : Processing Information
Data can be of any type – text, numeric, alpha-numeric, image, picture, sound etc. The instructions that act upon this data are also called the program or software in computer terminology.
1.2.1 Characteristics of Computers
The characteristics of computers that have made them so powerful and universally useful are speed, accuracy, diligence, versatility and storage capacity : Speed Computers work at an incredible speed. The speed with which it performs is way beyond human capabilities. As a comparison, it can do in one minute what a human being would probably take a lifetime! When we refer to the speed of computers, we have to talk in terms of milliseconds (hundredth of a second), microseconds (millionth of a second), nanoseconds (billionth of a second), and even picoseconds (trillionth of a second). A powerful computer is capable of performing about 3-4 million simple instructions per second. Accuracy In addition to being fast, computers are also accurate. Errors that may occur can almost always be attributed to human error (inaccurate data, poorly designed system or faulty instructions/programs written by the programmer) rather than technological weaknesses. In fact, a special term GIGO (Garbage in Garbage Out) has been coined to represent a scenario where faulty results are got due to inaccurate instructions or faulty data. Diligence Unlike human beings, computers are highly consistent. They do not suffer from human traits of boredom and tiredness resulting in lack of concentration. Computers, therefore, score high over human beings in performing voluminous and repetitive jobs. Versatility Computers are versatile machines and are capable of performing any task as long as it can be broken down into a series of logical steps. This means that their capability is, once again, limited only by human intelligence. As is evident, in today’s fast developing technology-world, it is almost inconceivable to find an area where computers are not being used. The presence of computers can be seen in every sphere – Railway / Air reservation, Banks, Hotels, Weather forecasting, and many more.
Storage Capacity Today’s computers can store volumes of data. Unlike human memory where...
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