Classification of Computers

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The classification of computers are generally done according to the following parameters:

  • (i) By size/appearance
  • (ii) By description/grade
  • (iii) By brand
  • (iv) By purpose
  • (v) By physical components and programs (Hardware and Software)

In the first place, we shall examine the classification of computers according to size/appearance.

Classification of Computers

According to Size / Appearance

The classification of computers according to size / appearance relates to the grouping of computers according to their physical structure. The computer classification from the largest to the smallest single unit is as follows:

  • Supercomputers, Mainframe Computers, Mini Computers, and Micro Computers
  • Supercomputers:

    A supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers are used for scientific and engineering problems (high-performance computing) which are limited by processing speed and memory size, while mainframes are used for problems which are limited by data movement in input/output devices, reliability, and for handling multiple business transactions concurrently.


  • See an example of a supercomputer below.

    IBM Supercomputer
    An Example of a Supercomputer

    Supercomputers have certain distinguishing features. Unlike conventional computers, they usually have more than one CPU (central processing unit), which contains circuits for interpreting program instructions and executing arithmetic and logic operations in proper sequence.

    The use of several CPUs to achieve high computational rates is necessitated by the physical limits of circuit technology. Electronic signals cannot travel faster than the speed of light, which thus constitutes a fundamental speed limit for signal transmission and circuit switching.

    This limit has almost been reached, owing to miniaturization of circuit components, dramatic reduction in the length of wires connecting circuit boards, and innovation in cooling techniques (e.g. in various supercomputers systems, processor and memory circuits are immersed in a cryogenic fluid to achieve the low temperatures at which they operate fastest).

    Rapid retrieval of stored data and instructions is required to support the extremely high computational speed of CPUs. Therefore, most supercomputers have a very large storage capacity, as well as a very fast input/output capability.

  • Mainframe Computers:

    The Mainframe computer (often colloquially referred to as "big iron") is a large computer system characterised by several banks of internal storage, multiple input/output devices and magnetic disk and tape storage. A mainframe computer will also have a variety of peripheral devices more than are found with smaller computers, and a large amount of backing storage.

    The processing speeds of modern mainframes are much faster than the speeds of small computers, although some modern 'super' microcomputers process data more quickly than some older mainframes. The internal storage capacity of modern mainframe is also much higher than the capacity of smaller computers.

    Additionally, mainframe computers are powerful computers used mainly by large organisations for critical applications, typically bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.

    A mainframe computer
    An Example of a Mainframe Computer


    The term originally referred to the large cabinets that housed the central processing unit and main memory of early computers. Later the term was used to distinguish high-end commercial machines from less powerful units.


  • Features of the Mainframe Computer:

    (i) Mainframe computers operate at a very high speed.

    (ii) Mainframe computers have many peripheral devices attached to them.

    (iii) Mainframe computers occupy very large space.

    (iv) Mainframe computers have large memory capacity.

    (v) Mainframe computers require special electrical wirings.

  • Mini Computers:

    A minicomputer (colloquially, mini) is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems (mainframe computers) and the smallest single-user systems (microcomputers or personal computers).

    Additionally, a minicomputer is a computer whose size, speed and capabilities lie somewhere, between those of a mainframe and a microcomputer. The term was originally used before microcomputers came along, to describe computers which were cheaper but less-equipped than mainframe computers (which had until then been the only type of computer available).

    With the advent of microcomputers and mainframes now being physically smaller than in the past, the definition of a microcomputer has become rather vague. The CIMA's computing terminology states that:

    "There is no adequate definition which distinguishes between a microcomputer and a minicomputer."

    Thus, the difference between mini computers and micro computers in terms of size, grade of the computer and speed of data processing have become so insignificant these days that the term "mini computer" is hardly used as one of the different classification of computers in use globally.


  • Micro Computers:

    A microcomputer is a computer whose CPU is based on a microprocessor. The British computer society's definition states:

    "Generally, this is a cheap and relatively slow computer with a
    limited immediate access store, a simple instruction set
    and elementary backing store (e.g. floppy disks)".

    Micro computers are general-purpose digital computers which were designed primarily to handle basic day-to-day office tasks. They are smaller in size and their data processing speed is by far lower than that of the mainframe computer. They are also referred to as personal computers. Micro computers come in two different forms – either as desktop or laptop or even palmtop computers.

    Additionally, the micro computer is named after the micro-processor which is a single micro chip that largely forms the brain of the computer and which the computer uses in its data processing.

    A typical microcomputer configuration consists of a central processing unit (CPU), random access memory, read only memory, hard disk drive, floppy disk drive, VDU screen and keyboard terminal which can all fit on to a desktop. A desk with computerised equipment on it is nowadays sometimes referred to as a workstation.

    Price, power and number of users supported have been used to provide distinguishing features, but these difference have tended to erode as microchip technology has progressed.

A mainframe computer A mainframe computer

An example of a Desktop Computer shown side by side with a Laptop Computer

Related Pages

Definition of Computer

Types of Computers

History of Computers

Computer Generations

Computer Classification by Grade

Computer Classification by Brand

Computer Classification by Purpose

Computer Hardware and Software

Computer Hardware, Parts and Accessories

Computer Software

Advantages of a Computer System

Disadvantages of a Computer System

Computer Security


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