Module 1
Introduction to Computer
Hardware
Computer Systems
Main Parts
Monitor
Floppy Disk
Drive
CD
CPU or
Drive
System box
Mouse
A Desktop Computer
Computer categories
Personal Computer – can be desktop,
laptop, palmtop etc. used by individuals
Mini Computers – used by medium-sized
companies or departments. Greater
processing power and speed than PCs
Mainframe Computers – huge expensive
machines used in banks and governments.
Can process huge numbers of transactions
and usually are working constantly i.e. 24
hours a day, 7 days a week
System Unit
Motherboard
Central Processing
Unit (CPU)
RAM
Power Supply Unit
Hard Disk
Floppy Disk Drive
CD
Modem (if internal)
Motherboard
Everything goes through the motherboard
CPU
Memory
Expansion Slots
Disk Drives
Power Supply
A computer has 3 basic parts
Keyboard and Mouse (Input)
System or CPU (Central Processing
Unit)
Monitor (VDU – Video Display Unit)
(Output)
CPU
The CPU can be termed the ‘brain’ of the computer.
It co-ordinates all the activities of the computer.
The speed of the CPU is mentioned when buying a
machine e.g. Pentium 500, which means 500 million
pulses a second is the CPU speed of the computer.
The 3 Main Parts of a CPU
(Central Processing Unit)
ALU ( Arithmetic Logic Unit)
The ALU Carries out the arithmetical, comparative
and logical processes.
Immediate Access Memory
The Immediate Access Memory is where the data
used by the ALU is stored.
Control Unit
The Control Unit ensures that the program instructions are
followed in the correct sequence.
Input Devices
Trackball
A pointing device consisting of a ball housed in a socket
containing sensors to detect rotation of the ball about two
axes - like an upside-down mouse. The user rolls the ball with
his thumb or the palm of his hand to move a cursor.
Trackballs are common on CAD workstations for ease of use
and on modern portable computers, where there may be no
desk space on which to use a mouse.
Keyboard
 The standard
keyboard is known as
a Qwerty Keyboard
 Make sure all new
keyboards have Euro
symbol Alt Gr 4
 Must set keyboard to
correct country
Mouse
Electro-mechanical
input device
Buttons used to
select items and
make choices
Smooth surface mouse mat
Trackball - move
ball not mouse
Touchpad
A touchpad is a touch-sensitive device which
replaces the mouse. When a finger is moved over
the surface, the result is similar to using a mouse or
Trackball
Light Pen
A light pen looks like a conventional writing pen but it
transmits electronic information to the computer.
Touch Screen
A touch screen enables the computer to be controlled
by a finger directly touching the screen.
Joystick
A joystick is a hand-controlled lever that can be
moved in all directions to control movement on the
screen.
Scanner
Digitises images so they can be edited and stored
on the computer
Image placed on glass surface then the scan head
and light moves underneath it
Quality determined by resolution
Resolution in Dots Per Inch (DPI)
Scan in text using Optical Character Recognition
(OCR)
Microphone
As well as allowing sound to be recorded on the
computer, a microphone can also be used to allow
speech to control the computer or to input spoken
text directly into a word processor.
Disk Drives
Data can also be input from floppy disks, zipped
drives, CD and DVD disks.
Output Devices
Plotters
A plotter is a special type of printer used
principally by architects, engineers and scientists.
LED Displays
Light Emitting Diodes (LEDs) are small light
sources commonly used to indicate the equipment
is switched on.
Examples are:
Most
calculators
Caps
Lock indicator on your keyboard
Disk
drive light
Monitor
The Monitor
Also Known as a Video Display unit (VDU)
Various sizes: 14”, 15”, 17”etc., measured
diagonally. 17” is the most common.
Screen resolution means number of dots
in the x and y coordinates.
Refresh rate - number of times per
second that image is drawn on the screen,
between 50-90 times.
Loudspeakers
Multimedia applications have made the use of
loudspeakers or headphones with a computer
essential. Loudspeakers are standard equipment in
modern computers used in the home.
Removable
Media
Data can be output to floppy disks, tape cartridges,
CD and other removable media for transfer to
remote computers for backup storage and for other
purposes.
Speech Synthesis
Software, when installed on the computer, can
produce sound that resembles human speech. This
can be used to assist people with disabilities or used
in areas where verbal feedback may be preferable
to visual.
Printers
Cartridges are very expensive
Two cartridges can cost the same as
a printer!
HP, Canon and Epson
Memory, Storage and
Performance
Storing Data
When the computer is switched on, the programs
are loaded into RAM (Random access Memory)
from the hard disk.
The computer uses RAM because anything
contained in RAM is instantly available to it.
It does not have to look for the information on
the Hard Disk as the information is read in at the
start.
RAM can only store data when the computer is
switched on. Everything in RAM vanishes when the
power is switched off (volatile).
Storage Devices
Hard disk. – The hard disk is located within the
computer system box. It is usually composed of several
metal magnetically created disks in a single unit and encased
is a sealed metal box.
Floppy disks – are small, portable versions of the hard
disks which use a magnetised plastic disk in a compact
plastic case 3½ inches square.
Zip Drives are similar units, they are small, portable
versions of the hard disk that use cartridges.
CD (Compact Disk) While floppy and hard disks are
magnetic, a CD is an optical disk which uses a laser to read
the information.
Hard Disk
Storage device
Rotating disk covered in magnetic particles
Write head magnetises the particles
Read head converts magnetic information
to a sequence of pulses
Non-removable sealed unit, vacuum
Solid aluminium disks
CD-ROM
Compact Disk Read
Only Memory
Looks like audio CD
Data can only be
read from it
Need special CD
writer and special
CDs to save