Computers can be classified on several bases as follows:
On the basis of electronics or the operating principle, they can be classified into:
Analog computer operates on inputs of continuously varying electrical voltage. It measures the input rather then counting. These are powerful tools to solve differential equations. They are mainly used in scientific design and production environments.
All quantities are expressed as discrete digits or numbers and computations are done with numerical digits. Mathematical expressions are represented as binary digits (0 and 1) and all operations done using these binary digits at a very high rate. The digital computer basically knows addition. It converts other operations into addition then calculate. It is much faster than analog computer, Computations are far more accurate.
Hybrid computer combines features of both analog and digital computers. In this computer some calculations are done in the analog portion of the computer and some are done in the digital portion of it.
On the basis of purpose of use, they can be classified into:
Special purpose computer
Special purpose computer is tailor made soley to cater to the requirements of a particular task or application.
Ex: Weather forecasting
General purpose computer
The general purpose computer is designed to meet the needs of many different applications. The instructions needed to perform a particular task are not wired permanently into the internal memory. Ex: Pay-bills,reports etc.
On the basis of size, they can be classified into:
Portable computer is very small easily carried to anywhere they go. Business executives,travelling salesman etc. Use it. This group includes pen based computer,hand held computer,note book computer and laptop computers.
It is larger than portable computers. It is normally installed on a desktop and hence the name ‘desktop computer’. These are used as personal computers. This has a main memory of 16 MB,128 MB and computing power of 2 MIPOS and above.
Mini computer is a medium sized computer that is costlier and more powerful than a micro-computer. This can support several users at a time, which multi-terminal time sharing system. These are used in business,medium sized organizations,universities and government departments.
The earliest computers were called mainframe due to their size. The term is still used for the large computers of today. They have large storage capacities,very high speed of processing. These are kept in A/c. These are used by big companies,banks etc.
This has extremely large storage capacities and computing speeds that are at least 10 times faster than that of other computers. These are traditionally been used in scientific,military,engineering,electronics,petroleum engineering,medicine and physics.