Total Computer System Essay

Identify the constituent parts of a total computer system

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Hardware - input and output units

Backup storage; central processing unit;

Software - applications package;

Operating system;

The main function of a computer system is to process data. When data has been processed and output it becomes information. The main stages of this procedure are:

1. The Input Stage - where data is put into the computer.

2. The Processing Stage - where the data is processed.

3. The Output Stage - where the results are displayed.

A computer also needs to store data for later use. This is done on a backing storage device.

Hardware - input and output units

INPUT DEVICES

CENTRAL PROCESSING UNIT

CPU stands for Central Processing Unit. It is the 'brain' of the computer. In fact, it is a microprocessor (chip) fixed to a circuit board inside the computer.

There are three main parts of the CPU -

1. The A.L.U. (Arithmetic and Logic Unit), which does all the arithmetic and logical operations.

2. The Main Store Memory. This is where data and programs are stored.

3. The Control Unit. This is the part, which controls the sequence of all computer operations.

Arithmetic Logic unit is the part of the computer where all calculating and testing happens. Data is sent to and received from the the ALU by the control unit.

Computer memory can be divided into two main types, main store and backing store. Main store consists of a large number of electronic circuits and all data and information that is processed by the computer has to go through main store.

When a sequence of instructions (program) is being executed by the computer system the control unit ensures that the data that is used within the computer is collected and sent from the peripherals and the special registers (special areas of RAM). As long as the data

Larger computers such as mainframes operate differently from the simple PC. They can process two or more programs at the same time and may have to deal with many users at the same time. This sort of operation requires very complex operating systems.

Some general features of operating systems are:

* they control the backing store and peripherals such as disk units and printers

* they control the loading and running of programs

* they organise the use of memory between programs

* they organise processing time between programs and users

* they organise priorities between program and users

* they maintain security and access rights of users

· they deal with errors and user instructions

MODES OF OPERATION

Computers can operate in many different ways requiring different and complex operating systems.

Real time processing

A real time system responds to incoming data immediately. Computers that run in real time have to be very fast and have a lot of processing power.

Computers operating in real time are often dedicated to the control of systems such as industrial processes, planes and space flights. The computer has to react immediately to input data by issuing