Introduction to Computers

Classification of Computers Lesson I

By the end of this lesson you should be able to: Classify computers according to their physical sizes

Classification of Computers Lesson I

Classification According to Physical Size

  • Supercomputers
  • Mainframe Computers
  • Minicomputers
  • Microcomputers


It is the largest, fastest and most expensive. Used for scientific research and forecasting which involves a lot of calculations.


  • They are able to perform many complex calculations in a few seconds.
  • They are kept in a special room due to their extreme weight.
  • They process data in large quantities hence generating a lot of heat.
  • Supercomputers require special cooling systems.
  •  Supercomputers are mainly used for scientific research which requires huge calculations.
  • They have a very high storage capacity.
  •  Examples of supercomputers are CRAY T3D and NEC- 500
  • Supercomputers are mainly found in developed countries such as in USA where they are used for advanced scientific research such as nuclear physics.

Mainframe Computers

Less powerful compared to supercomputers but more powerful than minicomputers. The main difference between mainframe and supercomputers is that supercomputers channel their power into processing a few programs as fast as possible while mainframes channels their power into processing many programs simultaneously (parallel processing).

It supports many concurrent users

It is mainly for commercial applications i.e handling daily transactions and batch data processing

Characteristics of mainframe computers.

  • - They are physically smaller than supercomputers.
  • - Supports a large number of peripheral devices.
  • - They are less powerful and expensive as compared to supercomputers.
  • - They are used for processing data and performing complex mathematical calculations.
  • -  They have a high storage capacity as compared to minicomputers and microcomputers.
  • - Mainframe computers handle all kinds of problems whether scientific or commercial.
  • - They are kept in an air-conditioned environment in a special room.
  • They are mostly found in government agencies, big organizations and companies such as banks, hospitals, airports etc.
  • Some Examples of mainframe computers are IBM 4381, ICL 39 series, and CDC Cyber series.



It is less powerful than the mainframe but more powerful than microcomputers. It is smaller in size compared to a mainframe computer.

  1. They are physically smaller than mainframe computers.
  2. Supports fewer peripheral devices as compared to mainframe computers.
  3. They are less expensive as compared to supercomputers.
  4. Lower storage capacity compared to mainframe computers.
  5. Minicomputers are mainly used in business and commerce.
  6. An example of a minicomputer is PDP-8 launched in 1965
  7. They are heavily used as network servers up to date.


They are the smallest, cheapest, and least powerful. Examples are Desktop, laptops, tablets, smartphones, and smartwatches

Microcomputer is the smallest, cheapest and relatively least powerful type of computer. The term microcomputer evolved from the word microprocessor which is the brain of a micro-computer.

  • Microcomputers are also called personal computers (PC) because they are designed to be used by one person at a time.     
  • Microcomputers are commonly used in training and learning institutions, small business enterprises, hospitals, homes etc. smaller and smaller microcomputers have been introduced i.e.
  1. The desktop computer- It is designed to be placed on top of an office desk and it is not portable.
  2. The laptop computers – Designed to be used by placing it on the lap hence its name. It is portable like a briefcase.
  3. The palm top – It is small enough to fit in the pocket and can be held on the palm when being used.

NB: The above-mentioned microcomputers are arranged in descending order according to size.

Advantages of laptop computers

  1. They are portable
  2. Displays clear images which prevent eye strain.
  3. Laptop batteries serve as a built-in uninterruptible power supply.

Disadvantages of laptop computers

  1. Many laptops have similar memory capacities.
  2. Laptops have few connecting ports and no growth potential.
  3. Security - Laptops are easy to steal.

The image below is a supercomputer


By Trower, NASA: Supercomputer