Computer System


A computer system is the combination of different computer hardware that works together to achieve common objectives. In other words, a computer system is the set of hardware and software which work together to process data according to the instruction given by the user in order to give information. Computer hardware and software work together to perform the tasks given by the user.
A computer system performs mainly five basic operations in order to convert raw data into meaningful information. They are:


The process of entering data and instructions into the computer.


Saving data and instructions so that they are available as and when required.


Performing arithmetic operations or logical operations on data in order to convert them into useful information.


The process of producing useful information or results for the user.


Directing the manner and sequence in which all the above operations are performed.
Fig. Working of Computer System

Input Unit

Computer System - Input / Output devices and Processing unit


Data and instructions must enter the computer system before any computation can be performed on the supplied data. Input devices accept data and instructions from the user. in short, the following functions are performed by the input unit:
  • It accepts the list of instructions and data from the outside world.
  • It converts these instructions and data into computer acceptable form i.e. binary code.
  • It supplies the converted instructions and data to the computer system for further processing.
The commonly used input devices are keyboard, mouse, joystick, touchpad, microphone, scanner, digital camera, and so on.

Central Processing Unit (CPU)

Computer System - Input / Output devices and Processing unit

The CPU is the brain of any computer system. In the human body, all major decisions are taken by the brain, and all other parts of the body function as directed by the brain. Similarly, in the computer system, all major calculations and comparisons are made inside the COPU and the CPU is also responsible for activating and controlling the operations of other units of a computer system. A microprocessor is a single chip that performs the functions of the CPU in microcomputers. The speed of a microprocessor is measured in terms of Megahertz (MHz) or GigaHertz (GHz). The CPU consists of an arithmetic logic unit, control unit, and memory unit.

a. Arithmetic and Logic unit

The arithmetic and logic unit (ALU) of a computer system is the place where the actual execution of the instructions takes place during the processing. To be clearer, all calculations and decisions are made in the ALU. The data and instructions stored in the primary memory before processing, are transferred as and when needed to the ALU where processing takes place. ALU is designed to perform the four basic arithmetic operations- add, subtract, multiply, divide, and logical comparisons such as less than, greater than, or equal to.

b. Control Unit

Although the control unit does not perform any actual processing on the data, it acts as a central nervous system for the other components of the computer. It manages and coordinates the entire computer system. it obtains instructions from the program stored in the main memory, interprets the instructions, and issues signals that cause other units of the system to execute them.

c. Memory unit

The memory unit or the primary memory is a part of the CPU where the instructions and data to be processed are stored temporarily. it holds the data and program currently being used. Data are sent to the ALU from the primary memory for further processing and the processed data are returned to the memory unit. Then, the data are sent to the output unit or secondary storage unit for storage. So, the primary memory is the working space used by a computer to hold the program and data that are currently running.

Two most used primary memory unit

  • Random Access Memory (RAM)
  • Read-Only Memory (ROM)

Most used secondary memory unit

  • Floppy disk
  • Hard disk
  • CD-ROM
  • Pen drive
  • Memory card

Output Unit

Computer System - Input / Output devices and Processing unit
The job of an output unit is just the reverse of that of an input unit. It supplies information and results of computation to the outside world. Thus, it links the computer with the external environment. In short, the following functions are performed by an output unit.
  • It accepts the results produced by the computer which is not understandable to us.
  • It converts the result into a human-understandable form.
  • It supplies the converted results to the outside world. The commonly used output devices are monitor, printer, plotter, and speaker.


Software is also a major part of the computer system. It is used to operate the computer. It enables the computer to do work. It is not possible to operate a computer system without software. it instructs and coordinates all the physical parts of the computer system.

Similar Posts

One Comment

Leave a Reply

Your email address will not be published. Required fields are marked *