1.1.1 INTRODUCTION TO DIGITAL COMPUTER

 Definition of Computer

A Computer is an electronic device that takes data and instructions as an input from the user, processes that data, and provides useful information as output.

 

The activity of processing data using a computer is called data processing. Thus, computer is also known as data processor. Data processing consists of three sub-activities:-

·         Capturing the input data (Input).

·         Manipulating the data (Processing).

·         Managing the output result (Output).

 

Fig 01: Computing Process

CHARACTERISTICS OF COMPUTER

The power and usefulness of computer is due to its following characteristics:-
 

1. Automatic:

A machine is said to be automatic, if it works by itself without human intervention. Computers are automatic machine because once started on a job, they carry on until the job is finished, normally without any human intervention.

2. Speed:

A computer is a very fast device. It can perform in a few seconds, the amount of work that a human being can do in an entire year if he worked day and night and did nothing else. While talking about the speed of computers, out units of speed are micro seconds (10^-6), the nanoseconds (10^-9) and even the picoseconds (10^-12).

3. Accuracy:

The accuracy of computer is consistently high and the degree of accuracy of a particular computer depends upon its design. Errors can occur in a computer. However, these are mainly due to human rather than technological weaknesses. 

4. Diligence:

Unlike human beings computer is free from monotony, tiredness and lack of concentration. It can continuously work for hours, without creating any error. If ten million calculations have to be performed, a computer will perform the tenth millionth calculation with the same accuracy as the first one.

5. Versatility:

Versatility is one of the most wonderful things about the computer. One moment it is preparing the results of an examination, the next it is busy preparing electricity bills and in between, it may be helping an office secretary to trace an important letters in seconds.

6. Power of remembering:

A computer can store and recall any amount of data or information because of its secondary storage (a type of detachable memory) capability. Every piece of information can be retained as long as desired by the user, and can be recalled, as and when required. Even after several years, the information recalled would be as accurate as on the day it was fed into the computer. A computer forgets or loses information when it is asked to do so.

7. No I.Q. :

A computer is not a magical device. It possesses no intelligence of its own. Its I.Q. is zero, at least until today. It has to be told, what to do and in what sequence. Hence, only the user can determine what tasks a computer will perform.

8. No feelings:

Computers are devoid of emotions. They have no feelings and no instincts because they are machines. Although men have succeeded in building a memory for the computer, but no computer possess the equivalent of a human heart and soul. Their judgment is based on the instructions given to them in the form of programs that are written by us.