what do you mean by computer? Describe the basic organisation of a computer system?

Subject Introduction to Computer System
NU Year Set: 1.(a) Marks: 8 Year: 2010

programmable electronic device designed to accept data, perform prescribed mathematical and logicaloperations at high speed, and display the results of these operations. Mainframes, desktop and laptopcomputers, tablets, and smartphones are some of the different types of computers.Compare analog computerdigital computer.

Basic Organization Of Computer System:

1. Input:

It is the process of feeding data and instructions to a computer system

2. Store:

It is the process of saving the data and instruction for the use of the system as and when required.

3. Processing:

It is the way of carrying out arithmetic(addition, subtraction, multiplication and division) or logical(comparison) operations on data in order to convert them to useful information.

4. Output:

It is the process of presenting the final result for the user in printed or visual display format.


Keyboard, mouse, joystick, scanner smartcard, microphone.

Primary Storage



Display Screen, Printer, Plotter, Speaker.

Secondary Storage

Magnetic disk, Optical disk, Solid state memory.

Indicate control flow for proper operation

5. Control:

It is the most important operation of the computer in which all four operations described above are coordinated and synchronized.

Though the internal architecture of different computers vary from one system to another, the basic organization remains the same. The block diagram given here may instill a basic idea of a modern computer system and its working.

We shall now discuss briefly the structure and working of different sections of a digital computer as shown in the previous diagram.


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