Computer systems

[1] A computer is known to be a device that has the ability to accept, store and process enormous quantities of data. Computers can be divided into three main types, depending on their size and power.

Mainframe computers are the largest and most powerful. They can handle large amounts of information very quickly and can be used by many people at the same time. They usually fill a whole room and are sometimes referred to as computer installations. They are found in large institutions and government departments.

Minicomputers, commonly known as minis, are smaller and less powerful than mainframes. They are about the size of an office desk and are usually found in banks and offices. They are becoming less popular as microcomputers are being improved.

Microcomputers, commonly known as micros, are the smallest and least powerful. They are about the size of a typewriter. They can handle smaller amounts of information at a time and are slower than the other two types. They are ideal for use as home computers and are also used in education and business. More powerful microcomputers are being gradually produced; therefore they are becoming the most commonly used type of computers.

[2] A computer can do very little until it is given some information. This is known as the input and usually consists of a program (a set of instructions, written in a special computer language, telling the computer what operations and processes are to be carried out and in what order they should be done) and some data (the particular information that has to be processed by the computer). Data brought out of the computer is known as output. Information in the form of programs and data is called software.

[3] The pieces of equipment making up the computer system are known as hardware.

The most important item of hardware is the CPU (Central Processing Unit). It contains the processor and the main memory. The processor is the brain of the computer. It does all the processing and controls all the other devices in the computer system. The main memory is the part of the computer where programs and data being used by the processor can be stored. However, it has a limited capacity.

[4] All the other devices in the computer system, which can be connected to the CPU, are known as peripherals. These include input devices, output devices and storage devices.

▪ An input device is a peripheral, which enables information to be fed into the computer. The most commonly used input device is a keyboard, similar to a typewriter keyboard.

▪ An output device is a peripheral, which enables information to be brought out of the computer, usually to display the processed data. The most commonly used output device is a specially adapted television known as a monitor or VDU (Visual Display Unit). Another common output device is a printer. It prints the output of the CPU onto paper.

▪ A storage device is a peripheral used for the permanent storage of information. It has a much greater capacity than the main memory and commonly uses magnetic tape or magnetic disks as the storage medium.

These are the main peaces of hardware of any computer system whether a small “micro” or a large mainframe system.

Ex.21. Match each component in column A with its function in column B.

A B

1) storage device a) It allows data to be entered. With it you communicate with your

computer.