A Computer is a system of hardware which can accept data (observation, facts & concepts) in prescribed form (i.e. in a specified sequence) and which can process the data according to set of instruction that are fed into it & supply the results of the processing in a specified format. As information, which in turn assists computer user in decision-making, or as signals to control automatically further machine or process? Or store the result in a primary /secondary storage for safekeeping or later reuse. In simplest terms a computer is an electronic machine for accepting & processing of data & help in retrieving information when needed.
Computer Classification:
On the basis of the usage of data computers can be classified as:
1. Analog Computers.
2. Digital Computers.
3. Hybrid Computers.
Analog Computers: Is in which numerical magnitudes are represented by physical quantities, such as electric current, voltage or resistance, mechanical movements etc.Analog computers accept data & then process it to produce analog data.
Digital Computers: A digital computer on data in the form of digits, rather than the physical quantities used in analog computers. That is, its input must be discrete rather than continuous & may consist of combination of numbers, characters & special symbols, written in appropriate programming language.
Classification of digital computers:
1. General-purpose digital computer.
2. Special purpose digital computer.
General-purpose digital computer: This is also called all-purpose digital computer. It can be used for any type of application e.g.: Computers that are used for payroll, graphics, and analysis etc. Special purpose digital computer: These computers designed to solve problems of a restricted type i.e. designed to be especially efficient in a certain class of applications.
Ex: Computer installed in washing machine.
Hybrid Computers: Hybrid computer is the outcome of the integration of analog computer components & digital components. This integration is obtained by digital –to-analog converter and analog –to-digital converter. A hybrid computer may use or produce analog data or digital data. It accepts a continuously varying input which is then converted into a set of discrete values for digital processing. Hybrid Machines are generally used in scientific applications or in controlling industrial processes.
Characteristics of Computers:
Speed: A computer speed is generally expressed in Megahertz (MHz), millions of machine cycles per second. Thus a PC listed at100MHz has a processor capable of handling 100 million machine cycles per second. Another measure of computer speed is MIPS (One million per second).A third measure of speed is the mega flops (MFLOPS), which stands for one million floating point operations per second. It measures the ability of the computer to perform complex mathematical operations.
Reliability: Computers are extremely reliable, where reliability is the measurements of the performance of a computer, measured against some predetermined standard against for operation against some predetermined standard for operation without the failure of it.
Accuracy: The accuracy of the results obtained from computer mainly depends on the method of programming & the ways the result are interpreted.
Storage Capability: Computer systems can store data tremendous amount of data, which can be located & retrieved efficiently. Mainly Computer system consist of 3parts
1. Hardware
2. Software
3. User
Computer Hardware consists of different parts like Central Processing Unit, Input hardware, output hardware, secondary storage and optical storage.
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