Types of Computer



All around the world, there are different types of computers used by different people at different places. The types of computers can be classified into different categories on the following basis:
  1. On the basis of work.
  2. On the basis of size.
  3. On the basis of Brand.
  4. On the basis of Model.

The chart below shows the classification of computers.

Fig. Classification Chart of Computer

1. On the basis of Work

On the basis of the working principles, there are three types of computers. They are:
  • Analog Computer
  • Digital Computer
  • Hybrid Computer

a. Analog Computer

An analog computer is one that measures physical quantities such as temperature, pressure, voltage, and current. Analog computers are especially suited for the solution of complex equations. Firstly, all operations in an analog computer are performed in parallel. Secondly, data are represented in an analog computer as voltages. Analog computers are specific purpose computers.
Speedometers in cars and motors are examples of analog devices. Some examples of analog computers are Seismograph, Presley, and so on. Also, the devices which measure the size of kidney in hospitals are analog computers. Hetauda Cement factory is also using an analog computer names Process Control. Among all the computers in Nepal, analog computers are less than 1%.

b. Digital Computer

A computer that stores data in terms of digits (numbers) is known as a digital computer. Digital computers are general-purpose computers. In digital computers, letters, words, and whole texts are represented digitally. Digital computers don’t measure distance, quantities of pressure. These computers are mostly used in the preparation of reports, results, tabulation, and graphic representations. They are mostly in mathematics, engineering, statistics, and so on. 99% of computers in Nepal are digital computers.

c. Hybrid Computer

A hybrid computer is a combination of Analog and Digital Computers. This integration is obtained by digital to analog and analog to digital converter. A hybrid computer may use or produce analog data or digital data. It accepts a continuously varying input which is then converted into a set of discrete values for digital processing. These computers are used in ICUs of hospitals to measure the heartbeat of the patient. Hybrid machines are generally used in big industries, scientific research institutions, airplanes, and other areas. Both the jet planes of the Nepal-Karnali and Gandaki area facilitated with hybrid computers and therefore, these planes are called computerized jet planes. Some hybrid computers are Flight Management Computers (FMC), Engine Indicator, and Crew Alert System (EICAS).

Differences between Analog and Digital Computer

Analog ComputerDigital Computer
It measures continuous data. It measures discontinuous or discrete data. 
It measures physical quantities such as temperature, pressure, voltage, and currents.It measures digital values like 0 and 1.
Some examples are Seismograph, Presley, Pressure control.Some examples are personal computers like desktops, laptops, and palmtops.

2. On the basis of Size

Computers are of various sizes. According to their size, there are mainly divided into three categories. They are:
  • Mainframe Computer
  • Mini Computer
  • Micro Computer

a. Mainframe Computer

They are the largest, fastest and perhaps one of the most expensive computers. Supercomputers are most powerful and expensive than mainframe computers but they are almost of the same size. These computers have a large storing capacity and high processing speed. 
These computers are multi-terminal systems as they are concerned with more than a hundred terminals (monitors). These computers can do the big capacity of processing tasks such as population census, Agro census, industries, SLC result processing, Provident Fund processing of Government employees, and so on. IBM 1401 was the first mainframe computer brought to Nepal for the population census of 2028 BS. ICL 1950/10 was another computer that was used for the 2038 census. These computers are still present in National Computer Center.

b. Mini Computer

These computers are smaller than mainframe computers in size. They are more powerful and expensive than microcomputers. These are also multi-terminal computers, as they are connected with more than 50 terminals at the same time. Nepal Rastra Bank, Agriculture Bank, Nepal telecommunication, National Computer Center, Police Headquarters, and electricity authority are using Mini computers. Some examples of mini computers is Data general, primer, neck, and so on.

c. Micro Computer

These computers contain a microprocessor as the main processor. They are also called Home computers or personal computers. Thye is mostly used at homes and offices. Nowadays, its capabilities and speed have increased. A small office is enough for microcomputers to set up. They are smaller than mini computers and are available in various sizes like desktops, laptops, palmtops.

i. Laptop

We call them laptops because they can easily be kept on the laps of users. They are portable computers which can be carried anywhere easily just like a briefcase. The personnel involved in such types of tasks, where they have to move from one place to another like to have laptops as they are easy to use and are handy.

ii. Palmtop

These computers are smaller than laptops and can be adjusted within the palm of the user.

iii. Desktop

These computers can easily be placed on a desk. So, we call it a desktop computer. These computers are specially used for personal purposes, hence they are also known as personal computers or PCs. Generally, we see these computers in schools.

3. On the basis of Brand

On the basis of brand, there are three types of computers. They are:
  • IBM PC
  • IBM Compatibles
  • Apple / Macintosh


IBM PC stands for International Business Machine Personal Computer which was made by IBM company established by Dr. Herman Hollerith in 1923 AD. It is the largest computer manufacturing company in the world even today. All the computers manufactured by this company are IBM PCs. These computers are more reliable, durable and they have higher processing capacity. They are also known as the Branded computers as all the parts of this computer are manufactured by IBM company itself.

b. IBM Compatibles

Compatible means ‘can be adjusted to work together. So, all the computers that are not manufactured by IBM Company but are the same in appearance and manufacturing like IBM PCs are known as IBM compatible computers. It is also called assembled PC as parts of different companies are assembled to make the computer. They are less powerful, less expensive, and less durable than IBM branded PCs. They are the most popular computers in the world today. They are also known as duplicates of IBM.

c. Apple / Macintosh 

Apple corporation is also one of the largest computer manufacturing companies in the USA. All the computers that are manufactured by Apple Corporation, USA are known as Apple/Macintosh Computers. In these computers, monitors and system units are attached to each other. These computers have their own hardware and software. They are mostly used in designing works.

4. On the basis of Model

On the basis of the model, there are three types of computers. They are:
  • XT (eXtended Technology)
  • AT (Advanced Technology)
  • PS/2 (Personal System-2)

a. XT

The computers having 8086 and 8088 microprocessors are XT computers. XT stands for eXtended Technology. They have a processing speed of 4.77 MHz.

b. AT

The computers having 80286, 80386, 80486 microprocessors are AT computers. AT stands for Advanced Technology. They have a higher capacity than XT. In these computers, apart from AT processors, math co-processors are also used for additional calculations.

c. PS/2

The new model computers manufactured by IBM after 1990 are known as PS/2 (Personal Syste-2) computers. These computers are used for general-purpose computation. They can run word processing, spreadsheet, database management, accounting package, and so on. The processing speed of these computers is higher than AT computers.

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