A device , which is used to accept raw data from us , processes them as per our instructions and produces results in the form of information , is known as Computer . Also , we say computer system is a general purpose machine that processes data according to a set of instructions that are stored internally. The instructions can be stored temporarily or permanently in the Computer System .
Classification Or Types Of Computer
|According To Data Representation||1. Digital|
|According To Purpose||1. General Purpose|
2. Specific Purpose
|Types Of Computer According To Use||1. Scientific|
|Classification Of Computer According To Size||1. Micro|
According To Data Representation
(a) Digital Computers – Digital Computers take input in the form of numbers, letters and special characters, store it and process it and give the output in the form of numbers letters and special characters. Such computers always process data (including text, sound, graphics and video) into a digital value (in O’s and 1’s) data flows in the form of pulses.
Digital Computers have the capabilities of adding, subtracting, multiplying. dividing and comparing. These computers provide highly accurate result. For example: (i) Desk Calculators, (ii) Electronic Computers
(b) Analog Computers – Analog Computers do not operate on digital data. Instead they operate on data presented to them in the form of continuously variable quantities like temperature, pressure, revolutions and the like.
They react in a pre-defined way to changes in the specified quantities. Analog computer is faster than the digit computer but can give a accuracy of not more than 99 % . These computer are suitable for use as controlling devices in factories, military weaponary, aerospace systems and the like. For example: (i) Speedometer (ii) Voltmeters (ii) Pressure Gauges (iv) Slide Rules (v) Flight Simulators for training pilots (vi) Wall Clock.
(c) Hybrid Computers – Hybrid Computers combine the features (capabilities) of both the digital and analog computers. They are suitable where digital processing is necessary in respect of data collected in the analog form. Both analog &hybrid are special purpose computers.
For example, in a hospital intensive care unit (I.C.U) measures a patient’s heart function, temperature & other vital signs. These measurements are in analog form. These measurements may then be converted into number (Digital form) & supplied to a digital device which may send as immediate signal to a nurses station if any abnormal reading are detected.
According To Purpose
(a) General Purpose – General purpose computers are the computers that can be used for all general needs of all environments and users. These computers can be used for various applications, ranging from scientific as well as business purpose applications. Even though such computers are versatile, they generally lack in speed and efficiency. For example, the computer that you use in your schools, colleges offices and homes are general purpose computers.
(b) Specific Purpose – This is the second types of computer as per purpose.These computers are designed to handle a specific problem or to perform a single specific task. A set of instructions for the specific task is built into the machine. Hence, these computers are not versatile. However, being designed for specific tasks, they can provide the result very quickly and efficiently. For example, airline reservations, satellite tracking, air traffic control, medical diagnostics, weather forcasting etc. are special purpose of computers.
Type Of Computer According To Use
There are two types of computer according to use namely Scientific computer and Business computer.
Type of Computer According To Size
(a) Super Computer – The fastest and most powerful type of computer Supercomputers are very expensive and are employed for specialized applications that require immense amounts of mathematical calculations. For example, weather forecasting requires a supercomputer. Other uses of supercomputers include animated graphics, fluid dynamic calculations, nuclear energy research, and petroleum exploration.
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently.
(b) Mainframe Computer – A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and moves to supercomputers at the top, mainframes are just below supercomputers. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe.
(c) Mini Computer – A midsized computer. In size and power, minicomputers lie between workstations and mainframes. In the past decade, the distinction between large minicomputers and small mainframes has blurred, however, as has the distinction between small minicomputers and workstations. But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously.
(d) Micro Computer or Personal Computer – is a small size computer.
- Desktop Computer: a personal or micro-mini computer sufficient to fit on a desk.
- Laptop Computer: a portable computer complete with an integrated screen and keyboard. It is generally smaller in size than a desktop computer and larger than a notebook computer.
- Palmtop Computer/Digital Diary /Notebook /PDAs: a hand-sized computer. Palmtops have no keyboard but the screen serves both as an input and output device.
(e) Workstations – A terminal or desktop computer in a network. In this context, workstation is just a generic term for a user’s machine (client machine) in contrast to a “server” or “mainframe.”