European Computer Driving
Licence
Module 1 – Concepts of IT
Chapter 1.2 Hardware
Pass ECDL4
1
Computer Essentials
Z Monitor – to display results of
processing
Z System Unit – this contains
all the basic computer
components that do all the
hard work
Z Keyboard – to enable text
and commands to be input
into the computer
Z Mouse – to enable the user
to point and click at pictures
and menus
Pass ECDL4
2
The System Unit
Z Can be contained in a tower
case or desktop case
Z Consists of a motherboard
which contains complex
electronic circuits and silicon
chips
Z All the computer components
plug into the motherboard
either directly into slots or by
cables
Pass ECDL4
3
Central Processing Unit
Z The main brain of the
computer which is a small
silicon chip with two main
parts
,
,
The control unit – fetches
computer instructions from
the computer’s memory,
decodes them and
synchronises the computer’s
operations
The arithmetic /logic unit
(ALU) where all the work is
carried out
Z Speed is measured in
Megahertz or Gigahertz
Pass ECDL4
4
Computer Memory
Z There are two kinds of
memory
Z RAM (Random Access
Memory)
,
,
Z ROM (Read Only Memory)
,
,
This is the computer’s
working memory
The more you have
installed, the faster your
computer will work
Pass ECDL4
Used to start your computer
and load Windows
ROM can only be accessed
by the CPU and cannot be
changed
5
What is RAM?
Z Used to store information on a
temporary basis (eg software, text
document etc)
Z CPU transfers information from the
hard disk drive to RAM
Z Information can then be processed
Z Information stored in RAM is
temporary
Z When the computer is switched off,
anything stored in RAM is lost
Z This type of memory is called
volatile memory
Pass ECDL4
6
An Example of RAM
Z Switch on the computer
,
,
The processor transfers
operating system
software from the hard
disk drive to RAM
The Windows desktop
appears
Z Double-click on the
Word icon
,
The processor transfers
the software from the
hard disk drive to RAM
Z Open a Word document
,
The processor transfers
the file information into
RAM so you can see it
and make changes to it
Z If you don’t SAVE the
document, the changes
will be lost when you
switch off the computer!
Pass ECDL4
7
What is ROM?
Z Used to store important
information that the CPU
needs to keep the PC
running
Z Information stored in ROM
,
,
,
can only be accessed by the
CPU and can’t be changed
is permanent and is retained
after the computer is
switched off
can be used repeatedly
Z This type of memory is called
non-volatile
Pass ECDL4
8
An Example of ROM
Z Switch on your computer
Z A Power On Self Test
(POST) and boot-up are
carried out to make sure
your CPU, memory chips
and other vital
components are working
,
,
If not, then an error
message will appear on
screen
Z The PC start-up software
is stored in ROM so it can
be used time and time
again.
If they are, then
information is transferred
to RAM to start up your
operating software
Pass ECDL4
9
How memory is measured
Z RAM is divided into millions
of units called Bytes
Z Each byte contains 8 bits
Z 1024 bytes = 1 kilobyte (Kb)
Z 1024 Kb = 1 megabyte (Mb)
Z 1024 Mb = 1 gigabyte (Gb)
Z 1024 Gb = 1 terabyte (Tb)
Pass ECDL4
10
Examples
Z Convert 2048KB to
Byte.
Z Convert 2048KB to MB
2048 KB = 2048 x 1024 Byte
2048 KB = 2048/1024 MB
= 2 MB
= 2097152 Byte
Pass ECDL4
11
Examples
Z Convert 2048KB to bit.
Z Convert 2048KB to GB
2048 KB = 2048 x 1024 x 8 bit
= 16777216 bit
2048 KB = 2048/(1024x1024)
GB
= 2048/1048576 MB
= 0.0019GB
Pass ECDL4
12
File Sizes
Z A simple Word document will
measure approx 20Kb
Z A 12 page report with
pictures will take up much
more space – maybe 300Kb
Z A 100 page user manual with
photos and screenshots
could be at least 2Mb in size
Z Microsoft Excel, for example,
takes up approx. 6Mb of hard
disk space
Pass ECDL4
6000
5000
4000
3000
2000
1000
0
Text
document
12 page
report
100 page
manual
Microsoft
Excel
13
Standard PC Memory
Z As computers have improved
so has the amount of
memory – look at the
following minimum
requirements:
,
,
,
,
Z If you wanted to run
additional software, you
would need to double the
above figures!
Windows 95 requires 8Mb
RAM
Windows 98 requires 16Mb
RAM
Windows Millennium
requires 32Mb RAM
Windows XP
requires 128Mb RAM
Pass ECDL4
14
Computer Performance
Z Two main factors will
determine how quickly your
computer works
,
,
The speed of the processor
(measured in megahertz or
gigahertz)
The amount of RAM
installed (measured in
megabytes)
Z Each time you launch
software, the program is
transferred to RAM
Z If you have several programs
running at once, this will slow
down your computer!
Pass ECDL4
15
Input devices
Z These are devices used to put data into the computer
Keyboard
Light pen
Mouse
Scanner
Trackball
Joystick
Microphone
Digital camera
Pass ECDL4
16
Output Devices - Monitors
Z Come in 15”, 17”, 19”, 21”
screen sizes
,
,
,
Z Resolutions
,
Picture is made up of
millions of dots called pixels
Picture quality depends on
number of pixels going
across and down the screen
Refresh rate is the number
of times the picture is drawn
on screen
,
800 x 600 is typical of a 15”
screen
1600 x 1200 is typical of
larger screens
Z Two different types
Pass ECDL4
,
,
CRT monitors – similar to a
TV screen
TFT monitors – much more
slim line
17
Output Devices - Printers
Z Inkjet printers
,
,
,
,
Z Laser printers
Mainly used by home users
Monochrome and colour
printing
Ink is forced through holes
onto the paper
Running cost quite high per
page
Pass ECDL4
,
,
,
,
Standard in most offices
Very high quality b&w
printing, very quickly
Suitable for large volume
printouts
Running costs quite low due
to high capacity cartridges
18
Output Devices - Printers
Z Dot matrix printers
,
,
,
Z Plotter
Steel pins hit an inked
ribbon
Very noisy and poorer print
quality
Used mainly by businesses
for printing out multi-part
invoices and wage slips etc
Pass ECDL4
,
,
Used mainly by architects
for printing large scale
drawings
Several coloured pens are
used to draw output on
paper or opaque film
19
Output Devices
Z Speakers
,
,
Connect to a soundcard
supplied with multimedia
PCs
Quality of the sound
produced can either be
controlled on the speakers
or from within software
Pass ECDL4
20
Input/Output Devices
Z Touch screen
,
,
Z Synthesiser
Allows the user to touch an
area of the screen rather
than typing from a keyboard
Used mainly in tourist
offices, bus information
kiosks ‫كشك‬and Job Centres
Pass ECDL4
,
,
Can be used as an input
device to input music to a
computer
Can be used as an output
device, for example
replicating human speech on
telephone systems
21
Storage Devices
Z These are needed to store
data on your computer
Z Most popular devices are:
,
,
,
,
Hard disk drive – this stores
all your programs and data
Floppy disk drive – this
stores smaller files
CD ROM drive – software
and games are normally
supplied on CD ROM disks.
Information is read-only and
cannot be changed
Pass ECDL4
,
CDR/CD-RW drive – large
amounts of data can be
stored on a CDR or a CDRW disk
DVD ROM drive – these can
be used to watch films etc
22
Other Storage Devices
Z Zip Drive
,
,
Z Tape Drive
Uses zip disks which can
store either 100Mb or
250Mb of data
Can be internal or can plug
into a PC’s USB port
,
,
Z Flash Drives
Z Jaz drive
,
Uses data cartridges for
backing up data on servers
Very slow access compared
to other options
,
Similar to a zip drive but can
store up to 1Gb of data
Pass ECDL4
,
Plug into a USB port
Typical storage – 32Mb,
64Mb, 128Mb and 256Mb
23
Removable Storage Comparison
Device
Capacity
Price of Drive
Floppy disk
1.44Mb
£10.00
£0.50
Zip
250Mb
£70.00
£11.00
Flash drives
256Mb
£60.00
N/A
CD
650Mb
£35.00
£1.00
Jaz
2Gb
£270.00
£80.00
DVD
4.7Gb
£120.00
£5.00
DAT
20Gb
£500.00
£40.00
Pass ECDL4
Price of Media
24