Introduction to the Computer System

What is a computer ?

A computer is an electronic device that can accept data and instruction, process them or store them for later retrieval, and sometimes generate output.

Advantages of Using the Computer

Some of the advantages of using the computer are:Computers can perform calculations much more quickly and accurately than humans.Large amount of data can be stored in a small amount of space.Computers can work continuously and perform repetitive tasks well.

Disadvantages of Using the Computer

Some of the disadvantages of using the computer are:The introduction of computers can result in loss of jobs.Computers make it easy for people to misuse informationThe using of computers can be expensive.There are health risks associated with excessive or improper use of the computer.

Major functions of Computer System

The major functions of the computer system includes:Input – accepting data or instruction from the user.Processing – manipulating data in a variety of ways to produce useful information.Output – presenting data or information to the user.Storage – holding data, information and instructions for future use

Major functions of Computer System Cont’d

Diagram outlining the functions of the computer system

Input Processing Output

Storage

Main Components of the computer System

The two main components of the computer system are:•Hardware – this consists of the physical components of the computer system, such as the mouse, monitor, keyboard, etc.•Software – this refers to the programs (or set of instructions) that direct the operation of computer system, such as the operating system, word processors, games, etc.

Categories of Computer hardware

1. The Central Processing Unit (CPU)2. Storage devices both primary and

secondary. 3. Input devices, which allow data to be

entered into the computer 4. Output devices, which are use for

outputting data from the computer .

Central Processing Unit (CPU)

The CPU is the device used for processing data by the computer. The CPU is the brains of the computer system and is also referred to as the processor or the central processor. It also controls the transfer of data between memory and the other devices.

Main Components of the CPU1. The control Unit (CU)2. The Arithmetic/Logic Unit (ALU)

The Control Unit (CU)The CU is the part of the CPU which control

the operation of the CPU. It is use to: 1.direct operations to the ALU when required2.control the flow of programs and data in

and out of the primary memory.3.read and interpret program instructions 4.control the flow of information to and from

all the components of the computer.

The Arithmetic/Logic Unit (ALU)This is the part of the CPU that does the following:

1. Performs arithmetic operations. These operation include addition, subtraction, division and multiplication. 2. Perform logical operations. These includes reasoning and performing the comparisons necessary to make decisions.

Storage Primary Storage Random Access Memory (RAM) Read Only Memory (ROM)

Secondary Storage Magnetic tape Floppy disk Microfilm Hard disk Optical disk (CD and DVD) Flash drive and Flash memory card

Storage Devices and Media

Definition of terms:

Storage Media – these refer to the physical hardware on which the computer keeps data, information and instruction for later use. Examples are floppy disks, hard disks, compact disks, etc.

Storage Devices – these are used for recording and retrieving the data, information and instructions from the storage media. Examples are floppy disk drives, hard disk drives, compact disk drives, etc.

Technical terms used with the storage of data

1. Bit – it is the smallest unit of storage 2. Byte – is a group of eight bits 3. Word – the size of the data or instruction

that the CPU can handle in a single cycle.4. Word- length /word size – the number of

bits in a word 5. Address – the location in memory where

data is stored 6. Character – any digit, letter or symbol

Input Devices Input Devices include:1. Mouse 2. Keyboard 3. Joystick 4. Scanner 5. Optical Mark Reader (OMR)6. Optical Character Reader (OCR)7. Magnetic Ink Character Reader (MICR)8. Microphone

Input Devices Cont’d9. Bar Code Scanner/Reader10.Point of Sale (POS) Terminal 11.Touch Screen/Terminal12.Graphics Pads and Tablets13.Digital Camera14.Light Pen15.Sensor

Output DevicesThe Output Devices includes:

1. Monitor (Visual Display Unit) 2. Printer 3. Plotter 4. Audio output devices (speakers, head-phone

and ear phone

Summary