Classification of Computer

On the basis of size:

Mainframe computer:

• The size is up to 10,000 sq. feet
• This computer supported above 100 users at a time and each user could use different application.
• Because of single machine use by multiple user information could be shared among the users confidently.
• Because of central executing station, any problem caused by one user disturbs all the users.
• There was single central administration to control the whole system.
• They had massive data storage facility.
• They were used by government agency, banking, insurance, university, etc.

Minicomputer:

• They had up to 50 terminals.
• The first minicomputer occupied 10 sq. feet area.
• There was a single control administration like main frame.
• They were used by mid range organization, business personals.
• They had relatively high processing power suitable for mid range organization.

Micro Computer:

• The micro computer is called personal computer as it has only one terminal.
• Smallest in size, can be kept on top of our palm, lap or desk; size is decreasing day by day.
• Their power consumption is very low in caparison to other types of computer.
• Due to their low cost they can be used at home, small business, colleges, general stores, etc.
• These computer supports multitasking, multimedia and networking.

Super computer:

• Super computer is the most expensive and the fastest computer.
• This computer can process complex mathematical equation in a few hours.
• They are used for highly calculation intensive task such as weather forecasting, climate research, molecular modeling, animated graphics, fluid dynamics, petroleum exploration, physical simulation other scientific and engineering research.
• Their memory hierarchy is very carefully designed to insure the processer is kept fed with data and instruction at all time.
• Their input output system is designed to support high band width.

Computer on the basis of data

Analog Computer:

Analog devices perform operates on data that are represented within the device by continuous variables having a physical resemblance to quantities such as electrical, mechanical and hydraulic. These devices process signals like voltage or frequencies. They are widely used to work on continuous system such as operation of air craft, nuclear power plants and industrial chemical process.

These are specific purpose computer dedicated to a single job only. Accuracy offered by Analog computer is less and output can vary even if the input is identical. It has no storage facility and output generated by analog device is difficult to interpret. E.g. Thermometer, Ammeter, Voltmeter.

Digital Computer:

It is a programmable device, that process information according to logical rules. It performs operations on binary digits. The binary information is represented in the form of electrical voltage. The discrete values such as ON, TRUE, YES are represented by binary number 1. The digital computer has tremendous impact in various fields. E.g. IBMPE, MA, Laptop.

Some important characteristics of digital computer are as follows:

• It uses binary digits (0, 1) to represent all form of information.
• It has huge storage capacity.
• The output generated by digital computer is easily readable by ordinary people.
• This computer is very accurate and output dose not vary for the same input.
• This computer are very flexible and reprogram is possible as programmed can be stored.

Hybrid Computer:

Hybrid computer shows both the features of analog and digital computers. These computers are capable of inputting and outputting in both digital and analog signals. They are used in hospital, Jet plane, industry, etc. It consists of both analog and digital parts. E.g. Modem, Hybrid watch, etc.

Computer on the basis of brands:

IBM Computer:

IBM introduced first personal computer (PC) named IBM 5150 in 1981. IBM PCs are general purpose computers. Because of their size and cost, they became affordable and useful to the ordinary people. Software applications such as word processor, spread sheet, browsers and games were widely used because of IBM PCs.

Apple Inc

Hewlett-Packard

Dell

Asus

Lenovo

Acer

Sony

Computers based on Purpose

General Purpose computers

A general-purpose computer is one that, given the appropriate application and required time, should be able to perform most common computing tasks. Personal computers, including desktops, notebooks, smartphones and tablets, are all examples of general-purpose computers. ENIAC, designed and built in the 1940s, was the first general-purpose computer.

Specific Purpose Computers

A Specific-Purpose Computer is designed to be task specific and most of its job is to solve one particular problem. They are also known as dedicated computers, because they are dedicated to perfom a single task over and over again.