Basic Components of Computer Systems and its Functions

Computer system

A computer system is an electronic device that can receive data, perform arithmetic and logical operation, and produces results.

The Computer systems consist of three basic components CPU(Central Processing Unit), Input, and Output devices. Input devices provide data ‘input to processors’ e.g. KEYBOARD, If we enter any button in the keyboard it can display the result in the output device e.g. (monitor). The processing of data is done by the CPU(Central processing unit).


  2. CPU(central processing unit)
    • CU(Control unit)
    • Memory unit


An input device is a hardware that is used to provide data to a computer used for entering data and programs in a computer system. Since the computer is an electronic device like any other machine which takes as inputs raw data and performs some processing giving out processed data, the input unit takes data from the user to the computer in an organized manner for processing.

Some of the popular components of input devices are a keyboard, mouse, joystick, microphone, Sound card/Sound chip, Webcam/Softcam, Video card/GPU(Graphics processing unit), etc.

2.CPU(Central processing unit)

The central processing unit(CPU) is the main processor of the computer that carries out the instructions of a computer program. It performs the basic arithmetical logical, and input/output operations of a computer system. It is also known as the Brain of the Computer because It controls the operation of all parts of the computer.

The first CPU was invented by an Italian physicist “Federico Faggin” who invented the first commercial CPU. It was the Intel 4004 released by Intel in 1971.

Some of the popular components of the CPU are Motherboard, RAM(random access drive), HDD/SSD(hard disk drive/solid-state drive), CD/DVD drive(compact disk/Digital versatile disc), SMPS(switch-mode power supply), Expansion card, Bus cable, Cooling Fans, etc.

In CPUs, There are three components:

a) CU(Control Unit)

A control unit is the component of the CPU(central processing unit). The control unit determines the sequence in which computer programs and instructions are executed. It integrates the operations of the computer and retrieves instructions from the main memory. It also acts like a switchboard operator where several users access the computer simultaneously.

And, it coordinates the activities of computer peripherals equipment as they perform as input and output. The components of the control unit are registers, control signals within the CPU, control signals from the bus, control bus, input flags, and clock signals.

b) ALU(Arithmetic and logic unit)

The arithmetic and logic unit is part of the CPU(central processing unit). It performs arithmetic and logical operations on data. An ALU can be designed by engineers to calculate many different operations like addition, subtraction, multiplication, division, shifting, etc.

The operation is performed on represented numbers, both integer and floating-point numbers.


A memory unit is also a part of the CPU(central processing unit) and it is an important part of a computer system where all the data are stored in the form of a Binary Digit (0&1). Computer systems use a variety of devices for storing instructions and data. A computer system is a place where the computers hold data and programs which are in use.

Computer memory refers to the physical devices in a computer, If our CPU had to constantly access the hard drive to retrieve every piece of data it requires.

Basically, the memory unit is broadly categorized into two types:


Primary memory includes RAM(Random Access Memory), ROM(Read Only Memory), etc. It has a faster access time, smaller storage capacity, and higher cost per bit of storage.


In secondary memory includes Hard Disks, Floppy disks, Magnetic disks, Magnetic Tapes, CDs/DVDs, etc.


Output devices are those devices that receive all the information from the computer and carry out the data that has been processed by the computer to the user. Output devices display information on the screen(monitor) or the printer sends the information to the other computers. And, also displays messages about what errors may be occurred and brings up a message or dialog box asking for more information to be input.

Some of the popular components of output devices are Speakers, Headphones, Screen (Monitors), Printers, Braille embossers, projectors, televisions, etc.


  • Input
  • Output
  • Storage
  • Processing
  • ALU(Arithmetic and logical unit)
  • CU(Control Unit)
  • CPU(Central Processing Unit)

For more details go to this link “Working Process Of a Computer”

Note: All points are mentioned in the blog of “working process of a computer“, they all are the function of the computer

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