What is computer? | Type of Computer | Modern Computers

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A computer is an electronic device. It needs our instructions to work. It works very fast and accurately. It can store a huge amount of information.
components of computer system

Components of the computer system

A computer is made up of four types of devices.
  1. Input Devices
  2. Processing Devices
  3. Output Devices
  4. Storage Devices

Input devices:

Input devices are the devices through which we enter data and instructions. The keyboard is the most commonly used input device. Some of the input devices are as follows.


A computer keyboard looks like a typewriter. It consists of a number of keys. We can input data by pressing the keys of the keyboard.


The Mouse is an input and pointing device. It is also used to give instructions to the computer. When the mouse is moved on a mouse pad, a pointer moves on the screen. This helps us to point and select items on the screen.


The scanner is used to insert/capture text and pictures directly into the computer. There are several types of scanners. Most of them look like a flat tray with a glass pane and a lid to cover it.

 Light Pen

Light Pen is also a pointing device. It can be used to select any option by simply pointing at it. By using it, we can draw figures directly on the screen of the s. computer.


A joystick is an input device. It is used to play games on the computer. It controls the movements in any direction.

Processing Device

Processing means performing logical and mathematical calculations or comparing data. CPU is known as the processing device. It is present in AMD the CPU box.
As you know, the brain is the most important part of our body. In the same way, the CPU is the most important part of a computer. It performs all the processing and decision making work on the computer. It also controls all the other parts of the computer system. Thus, it is called the brain of the computer.

The CPU consists of three parts :

  • Arithmetic and Logic Unit [ALU]
  • Control Unit [CU]
  • Memory Unit [MU] 
Have a look at this picture to understand the working of CPU.
  • MU – Memory Unit stores the input and output data.
  • CU – Control Unit controls all the parts of the computer CONTROL and the movement of data.
  • ALU – Arithmetic and Logic Unit performs all the arithmetical and logical operations.

Output Devices

An Output device gets the desired result on a monitor or printer after processing the input (Data). The most common device is a monitor. Some of the output devices are as follows :


A monitor is an input as well as an output device. It is also known as VDU (Visual Display Unit). It shows us what we type from the keyboard and also the results given by the CPU. The output shown on the monitor is called “Soft Copy!


The printer is another output device. It produces the output on a paper. Output prints on paper are called Hard Copy.


 Speakers are output devices. They play the sound generated by the computer. They are connected with the computer system.

Storage Devices

Besides these devices, the computer also needs some other devices to work. These devices are called storage devices. These devices are needed to store data and information. Some important storage devices or parts that are commonly used for the safe storage of work done on the computer are as follows :

Floppy Disk

It is a data storage device. It is made up of a ring of thin flexible, i.e., magnetic storage medium bu contained in a square plastic cover. It helps us to store data, but it has a low storage capacity.

Pen Drive

A pen drive is a small storage medium with a very large capacity. It is very popular these days for storing all types of data including audio, video, text, images, etc.

Compact Disk 

Common Disk is commonly known as a CD. It is round in shape and can store all kinds of data including audio, video, text, images, etc.


 The Digital Versatile Disk or DVD looks much like a CD but it can store much more data than a CD. Nowadays, it is popular for storing games, music, movies, etc.

Modern Computers

Modern Computers are smaller in size. They consume less electricity and works very fast. Besides Performing calculations, today’s computers help us to do a lot of things Some of the computers that we use today are shown.
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Types of computers

There are four main types of computers. These are : 
  1. Micro Computers 
  2. Mini Computers
  3. Mainframe Computers 
  4. Super Computers

Micro Computers

Micro Computers are very small computers. They are also known as Personal Computers or PCs. They are the most popular and multipurpose computers. They are generally used in schools, offices, shops, etc. to do various types of jobs.

Mini Computers

Mini Computers are more capable than microcomputers. They work faster and have more memory than microcomputers. These are used by big organizations like banks.

Mainframe Computers

Mainframe computers are very large computers. Their speed and storage capacity is much larger than the mini computers. These are mostly used for scientific research purposes.

 Super Computers

Supercomputers are the most powerful computers. They are very expensive. These computers are used for weather forecasting and to control satellites and the missiles.  PARAM 10000 is the name of the supercomputer designed by India.

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