Basic Components of Computer System

Components of a Computer System: A computer is a system of many parts or components that works together with the purpose of converting data into information.

Every computer system comprises multiple electronic components. We can broadly divide into two categories: hardware and software.

The physical components which we can see and touch are collectively known as computer hardware. Some examples of computer hardwares are CPU, monitor, mouse, keyboard, hard disk, etc.

On the other hand, software is a set of instructions or programs that tell the hardware what to do. Some examples of softwares are DOS (Disk Operating System), Windows, Oracle, Tally, etc.

There are many computer systems in the market with a wide variety of models and peripherals. The internal architectural design of a computer may little differ from one model to another.

But, the basic components or parts of a computer remain the same for all models. A laptop computer has the same parts, but combine them into a single notebook to make it compact size.

A computer system is a complete computer installation that contains the following main physical components or parts. They are as:

  • Input unit
  • Central processing unit (CPU)
  • Output unit
  • Memory or storage unit

The general architecture diagram of a computer system is shown in the below figure.

Components of computer system

In addition to the above main components, a computer system has other components, such as motherboard, power supply, ports, and cards. All devices of a computer system, except motherboard and CPU are known as peripheral devices.

Input Unit


The computer components that help humans put data into the computer are called input unit. An input unit is formed by connecting various input devices, such as a keyboard, mouse, touch screen, modem, scanner, etc.

An input device is an electromechanical device that takes instructions and data from the user. Instructions and data are entered into the computer memory through the input devices.

A computer receives input in two ways: either manually or directly. In the case of manual data entry, the user put the data into the computer by hand, either using keyboard or mouse. In case of direct entry, data is entered into the computer automatically from a source document, such as barcode.

As instructions and data put through different input devices are in the different form, the input unit converts them into a form that a computer can understand. After it, the input unit sends the data and instructions to the CPU for further processing.

Central Processing Unit (CPU)


The central processing unit (CPU) is considered as the “brain” of any computer system, which performs all the processing of input data. Its function is to convert data (input) into meaningful information (output).


In a microcomputer, CPU is a highly complex, extensive set of electronic integrated circuit (IC), which fetch, examine, and then execute program instructions stored in the main memory of a computer. We also call it a microprocessor that is basically a single chip.

A central processing unit controls all internal and external devices, as well as performs arithmetic and logical operations. It operates only on the binary data that consists of “1s” and “0s”.

Moreover, it also controls the usage of main memory to store program instructions and data, as well as controls the sequence of several operations. The central processing unit has three main subsystems:

  • Arithmetic and logic unit
  • Control unit
  • Registers

Output Unit


In a microcomputer, output unit is formed by connecting output devices, such as monitor, speakers, printer, and plotter to the computer.

An output device is a device that outputs or presents the processes data (result or information) to the user. The basic function of an output unit is just opposite to that of input unit.

It accepts the outputs (in machine coded form) from the CPU, and converts them into the user understandable form (which are called information) such as texts, audio, video, or graphical. After converting it, it sends the converted results to the user with the help of output devices.

User can understand and use the output either in the hard copy or soft copy. The physical form of output is called hard copy. The electronic form of an output, which usually stores in the computer memory and/or on the hard disk is called soft copy.

Memory Unit or Storage Unit


Memory or storage unit is that component of a computer system, which stores the program instructions, and data before processing starts and stores the information generated by computer before sending them to the output unit.

In other words, a computer system incorporates the memory unit to store input entered via input unit before processing starts aw well as stores the result generated by the computer before sending to the output unit.

A memory unit is basically that area within the computer system, where the CPU stores the program instructions and data. The memory unit or storage unit of a computer consists of two types of memory or storage. They are as:

  • Primary memory (also known as main memory)
  • Secondary memory

The main memory holds the program instructions and data currently being processed by the CPU, the intermediate results generated during the calculations, and the recently processed data. When the instructions and data remain in the main memory, the CPU can access them directly and quickly.

Because of the limited size of the main memory, a computer system uses a secondary memory, which is extensively used to store instructions and data. Then, it sends the stored information to other units of the computer as and when need.


In this tutorial, you have learned about the basic components or parts of a computer system with a diagram. Hope that you will have understood the basic points of all computer system components and enjoyed this tutorial. In the next, we will understand computer input devices.
Thanks for reading!!!

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