COMPUTER SYSTEM Components of a Computer System Definition

COMPUTER SYSTEM Components of a Computer System

Definition • A computer is a data processing machine that is under the control of stored programs which automatically accepts and processes data and supplies or stores the result of that processing. • A computer accepts data, processes the data and stores or supply the information to the user.

Classification of Computers • Classification According to the Display of Output • Digital Computers These are computers in which data and information are represented in digital form by a coded set of electrical pulses. Examples include: programmable calculators, mainframe, minicomputers and microcomputers. Digital computers have that advantage of accurate output, high arithmetic speed particularly in the solution of mathematical problems and mathematical modelling, ease of programming and coding. • Analog Computers These are computers in which data and information are represented in a more direct manner by a physical quantity that is proportional to it or to its defined function. Examples include, thermometer, pressure gauge, voltmeter, analog fuel pumps. Analog computers are very cheap and have the advantage of high speed of output but the output may not be accurate.

Classification of Digital Computers They can be classified into general purpose and special purpose. • General purpose digital computers are those computers which are completely programmable and can be used to perform a variety of numerical calculations and business problems. • Special purpose computers are digital computers are designed for special type of application and have their programs pre-written.

Digital General Purpose Computers • The computers used in the homes, schools, offices and for business • • • applications are all digital general purpose computers. Basically they are generally classified according to their processing power, memory, capacity and the number of peripherals that can be simultaneously supported such as Supercomputers; Mainframes; Minicomputers; and Microcomputers

Digital General Purpose Computers However, the rapidly changing technology has made this traditional classification very difficult. There are many super microcomputers that are more powerful (in terms of their processing speed) than the microcomputers, however, these features can be used in their classification. • Processing power (the overall speed and power of a microcomputer). This is frequency of the processor’s electronic clock, that is, how many cycles a computer can execute per second, which is measure in Hertz. • • • Memory capacity Heat evolution Environment in which the computer is used Cost Security measures put in place in the environment Installation procedure (maintenance inter-periods and the number of peripherals that can be simultaneously supported). Word size: the number of bit of data that can be processed in one cycle. Now 128 bit microprocessor chips are in use. Bus size: the number of bits transmitted at one time from one computer location to another. The capabilities of the peripheral devices and the extent of usage.

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