The Computer System

The Computer System

A Computer is an electronic device that accepts data in form of input through an input device process the data and yield results (output).

In order word computer can be defined as an electronic device that process data to yield useful information.      

Basic Functional units of a Computer

The basic computer system consists of five units:

i     Input Unit

ii    Control Unit

iii   Arithmetic Unit(contained in the CPU, or central processing unit),

iv   Memory Unit

v    Output Unit

This organization of the functional parts is called the architecture of the computer.

Fig 1.1 General Organization of a computer

Input Unit: This is the unit used for sending or transferring data, commands into the

Computer for processing, thereby helping users to communicate with the computer system, it acts as an interface between the user and the system.

Examples of input unit are:

i.                    keyboard,

ii.                  joysticks,

iii.                scanners,

iv.                light pen,

v.                  electronic tablet

vi.                Digitizer. Etc.

Processing Unit: This is the responsible for processing all the various operations that goes on in the system unit. It is referred to as the brain of the computer system, without it the computer will be valueless.

Example of processing unit is the central processing unit (CPU). 

The processing unit can be divided into three sections:

i     Control Unit

ii    Arithmetic and logical unit (ALU)

iii   Memory Unit.

 The Control Unit: This unit coordinates all the various operations of the input and output units in the system unit precisely the Central Processing Unit (CPU).

Functions of the control unit

i.                    It directs the sequence of operations,

ii.                  It interprets the instructions, of a program, in storage unit and produces signals the command circuits to execute the instructions.

iii.                It directs the flow of all activities in the computer system.

The arithmetic and logical unit:   This unit is responsible for performing all the various Arithmetic operation of addition, subtraction, multiplication, division and relational operations Such as not equal to (¹) greater than (>) less than (< ) greater than or equal to (≥) and logical operation. Etc.

The memory unit:  This unit otherwise known to be the main or primary memory (storage). It stores information (i.e. instruction data intermediate and final result of processing) that arrives via the input unit so that this information is made available to the appropriate Quarters for further processing after which they can be presented to the user via the Output unit.

  

The memory unit divided into two:

i.                    Random Access Memory (RAM)

ii.                  Read Only Memory(ROM)

Other versions of ROM are:

·         PROM(Programmable Read Only Memory)

·         EPROM.(Erasable Programmable Read Only Memory)

Output Unit: This unit displays the result of the processed data for the user

Examples of output unit are:

i.                     monitor (visual display unit-VDU)

ii.                   Printers

iii.                Card Reader

iv.                Magnetic Tape

v.                  Microfilm etc.