Standard Grade
Computing Studies
Computer Systems
Frank Frame
Computing Studies
Standard Grade
Computer Systems
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Acknowledgement
Thanks to Dorothy Tedman for her contribution to the review of the content.
First published 2004
This publication may be reproduced in whole or in part for educational purposes by
schools and colleges in Scotland provided that no profit accrues at any stage.
ISBN 1 84399 038 5
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Contents
Introduction
4
Types of Computer System Featured on DVD
6
Hardware Devices
8
Types of Input Device Featured on DVD
9
Types of Output Device Featured on DVD
14
Types of Backing Storage Featured on DVD
18
Questions and Tasks
24
Answers to Questions and Tasks
27
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Introduction
This publication is part of a series of publications to support Standard Grade
Arrangements in Computing Studies (March 2004). The titles in the series are:

General Purpose Packages

Communications and Networks

Computer Systems

Automated Systems

Commercial Data Processing.
The first two packs, General Purpose Packages and Communications and
Networks, provide complete coverage of the content as specified in the updated
arrangements for Standard Grade Computing Studies.
The other three packs, Computer Systems, Automated Systems, and Commercial
Data Processing have been produced to support the three programmes featured
on the DVD. The content of these materials has been written to relate directly to
the programmes on the DVD and may not cover all the content as specified in the
course arrangements.
Computer Systems
The materials contained in this pack support the programme on the DVD entitled
The Kickin’ Technology Top 20. The materials describe a number of items of
hardware associated with input, output and backing storage devices. The materials
cover the following content as specified in the course arrangements.
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Computer Systems – Content Covered In Support Materials
Main Aspect
Operating
systems
F/G/C
Low-level
machine
Hardware






input devices
(Computer
Systems)
output devices
(Computer
Systems)








megabyte (MB),
gigabyte (GB)
backing storage
desktop, laptop/
notebook, palmtop
current input
devices
current output
devices
current backing
storage devices
mouse
trackpad
graphics tablet
touch-sensitive
screen
sound card
keyboard
printer:
-laser
- inkjet
monitor (VDU)
G/C









Backing
storage
(Computer
Systems)




magnetic tape
floppy disk
CD-ROM
DVD-ROM







© Learning and Teaching Scotland
C

sequential and
random/direct
access to data
capacity of
backing storage
mainframe

sequential and
random/direct
access devices
digital still camera
digital video
camera
webcam
microphone

use of a variety
of input devices
for multimedia
Comparison of
printers in terms
of:
- speed (ppm)
- capital costs
- running costs
- resolution (dpi)
liquid-crystal
display (LCD)
thin film transistor
(TFT)
loudspeakers
Comparison of
backing storage
in terms of:
-speed (data
transfer)
- cost capacity
CD-Recordable
(CD-R)
CD-Rewriteable
(CD-RW)
DVD-Recordable
(DVD-/+R)
DVD-Rewriteable
(DVD-/+RW)
USB Flash Drive

use of variety of
output devices
for multimedia
sound card
graphics card


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Types of Computer System Featured on
the DVD
Mainframe
A mainframe computer is a
computer system with:
- very powerful processors
- lots of backing storage
- large internal memory.
Mainframes are designed to
process large volumes of data at
high speed. They are used by
large businesses such as banks
and mail-order companies as well
as by large organisations such as
universities.
Personal computer
A personal computer (PC) is a computer that is small and cheap enough to be
owned and/or used by a single person.
Desktop
A desktop computer is the most common kind of PC. It is a collection of a number
of different hardware devices. This type of computer is sited permanently on a desk
because its design means it cannot be easily moved. The common components of
a desktop PC are:








the system unit containing the
processor and main memory
monitor
keyboard
mouse
hard disk drive
floppy disk drive
CD/DVD drive
speakers.
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Laptop/notebook
A laptop computer is a small, light computer that you can easily carry about with
you. It can be powered by battery or mains power. A laptop computer has a
keyboard, and comes with specialised input devices, for example trackballs,
touchpads or trackpoints. They are needed because laptop computers are often
operated in places where it is impracticable to use a mouse.
For output the laptop has an LCD
or TFT screen and a set of small
speakers.
‘Laptops’ are often as powerful as
desktop computers and run the
same range and type of software.
People use laptops for working
when they are on the move, going
to meetings or attending courses.
Many businesses are replacing desktop PCs with special plug-in workstations
designed round laptop computers because of the flexibility they offer.
Palmtop (or PDA) computer
This type of computer is increasing in
popularity, and is often called a
Personal Digital Assistant (PDA).
A palmtop computer is small enough
to fit in your pocket.
It combines a lot of capabilities,
including organiser features (such as
storing contact numbers, names and
addresses etc.), e-mail and wireless
internet access.
Palmtops have small keyboards and most let you open menus and select icons by
using a special pen or stylus. Most let you enter data by writing with the stylus.
They are powered by batteries and store their data on removable memory units
called flash cards.
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----------------------------------------------------------------------------------------------------------You can run a wide range of software on palmtops, for example simple word
processing, database and spreadsheet software as well as useful applications
such as electronic diaries. Many modern palmtops:


are converging with mobile phones to let you access the internet
have wireless communications to let you access your local area network.
Hardware Devices
There are three categories of device that can be attached to computers we need to
know about:



input devices
output devices
backing storage devices.
The use of input devices and output devices are quite obvious – giving computers
instructions and displaying results. Backing storage is the permanent record of
work completed. Files or programs saved to these devices can be loaded later.
Input devices
A large number of different devices are to allow users to give information, or
input, to the computer. Text, numbers, sound, graphics, video, movement, heat,
touch, etc. can all be entered using the correct device.
Output devices
Output is usually limited to text, sound and pictures. Permanent paper copies are
produced using printers and plotters.
Printers use different technologies to produce paper hard copies (printouts).
Backing storage
In recent years backing storage devices have increased dramatically in their
variety and also the amount (capacity) of storage. This has dramatically
reduced the cost of storage per gigabyte1 of information.
1 Gigabyte: a unit of information equal to one billion (1,073,741,824) bytes or 1024
megabytes
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Types of Input Device Featured on DVD
Trackpad
Trackpads are found on laptops. The trackpad does the job of the mouse and lets
you:

control the cursor by dragging your finger across the pad

select items from menus or open up files by tapping on the pad.
Keyboard
This is the main input device for desktop and laptop systems.
It has keys for:



text entry
entering numbers
carrying out special functions such as printing the screen display.
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Mouse and trackball
A mouse is the other standard input device supplied with desktop computers. It is a
pointing device that allows the user to move a pointer or cursor across a monitor
screen. The mouse is a very important input device. It helps you to do many things,
such as:





controlling the cursor or pointer
opening up menus
selecting items from menus by clicking the mouse button
opening up software by clicking the mouse button
dragging icons to move them into folders, to save files.
Recent changes to improve the functionality of ‘mice’ include cordless mice,
optical mice, scroll wheels and extra buttons.
A trackball is like an upside-down mouse. Instead of moving the mouse round the
desk you move the ball you can see in the picture.
Trackballs were commonly found on laptop or notebook computers, but they are
sometimes replaced with mini-joysticks and trackpads.
Graphics tablet
This has a flat surface that can sense the slightest touch. Artists and designers use
it to enter drawings into a computer system. By dragging a stylus across the tablet
surface you can draw freehand and the drawing is entered exactly into the
computer’s memory.
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Digital still camera
How does it work?
1. A digital camera takes a photograph by using sensors to capture the light
that comes in through the lens.
2. It then converts the light into binary numbers that are recorded on
backing storage.
3. This digital version of the photograph can then be displayed on the small
screen that is set into the camera.
4. A digital camera also has software that lets you delete unwanted photos
while they are still stored in the camera.
5. You can connect your camera to your PC and transfer your photos across.
6. Once they are in the PC you can edit your photos further by using a
good graphics package.
What are the key features to look out for in a digital camera?
 The number of megapixels the camera has.
A megapixel is a million pixels. This is a measure of how accurately the camera
captures images. It refers to the number of sensors the camera uses to detect
the light. The more pixels, the better the quality of pictures the camera can
take.
 The amount of onboard memory the camera has.
 The larger the onboard memory the more photos it can store. Camera memory
sticks come in various sizes.
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Advantages of a digital camera




It can hold lots of photos without the need to buy film.
You can see what your photo is like straight away and you can delete any you
do not want.
The photos are digital so you can transfer them to your PC and then do all
sorts of things with them such as edit, print, store on a writeable CD, attach to
an e-mail.
You do not need to have photos developed, saving time and money.
Digital video camera
How does it work?
A digital video camera captures moving images using technology similar to
that used by a still digital camera.



It uses light sensors to capture the images.
The images are then changed into binary numbers.
The binary numbers are then stored in files on the camera’s backing
storage.
What are the key features of a video camera?
The accuracy of the image sensors used to take the film. This is measured by
the number of pixels that the camera uses to capture the images.
Backing storage
This varies in size and type. Some of the latest types use DVDs to store their
video files. They can hold up to two hours of video each or over 2000 still photos.
Once filming is complete the DVD can be viewed in a DVD player or transferred
to a PC for editing.
The type of display screen available on the camera
Some have small touch-sensitive screens that allow you to make selections and
edit your film. Others have small eyepieces that you hold up to your eye to view
what you have just filmed.
Touch-sensitive screens are display screens that are sensitive to the touch of a
finger or stylus. They are often used with custom-designed applications so that
the on-screen buttons are large enough to be pressed with the finger.
Applications are typically very specialised and greatly simplified so they can be
used by anyone. However, touch-sensitive screens are also very popular on
Personal Digital Assistants (PDAs) and full-sized computers with standard
applications, where a stylus is required for precise interaction with screen objects.
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The onboard editing features
The software that comes with the camera can be quite powerful offering the user a
whole range of features such as:





focus
adjustable lighting
infrared
zoom
special effects.
Webcam
This is a digital camera that is used to take photos and then send them across the
internet. Webcams capture and transmit still photographs that can be updated at
various speeds, from one frame every few minutes, to full streaming video,
depending on the speed of the computer system and the software settings.
The technology for capturing the images is similar to that used in the other
digital cameras.
The difference is that once an image is captured it is transmitted automatically to a
computer system. Webcam software in the computer system then transfers it to a
web page.
What are webcams used for?
They are used for a wide range of
purposes; some examples are to:




© Learning and Teaching Scotland
set up videoconferencing
monitor traffic
advertise tourist sites
advertise businesses.
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Types of Output Device Featured on DVD
Printer
Computers were supposed to bring about the dream of a ‘paperless office’.
This now looks very unlikely to happen because paper has got some
advantages over computers when looking at information.



It is very portable. The information on a sheet of paper is easily passed
around, and many people can look at the information at the same time.
It is cheap. Initial costs of computers means there is no comparison with
the cost of using paper.
Not everyone has computer equipment to view information, or it may be
difficult to use computers in some situations.
Paper copies, or hard copies, of information will always be needed. Printers (and
plotters) are used to produce these hard copies. The main different types of
printer, and how they are compared against each other, are explained below.
Laser printer
This type of printer is the main one used in schools, offices and industry
because it produces high-quality printouts very quickly, with good resolution. It
uses a laser to make a negative electrical image of the page on a positively
charged drum, which then picks up positively charged toner. The drum rolls over
the paper and the toner is heated to print on to the page. The toner cartridge
gives many copies before needing replaced keeping running costs down.
While it is the most expensive to buy, especially for colour, the price of this
printer has fallen dramatically.
Laser printers are generally more expensive than inkjet printers, but their
running costs are lower.
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Inkjet printer
Basic models of this type of printer are cheap to buy, and let you print in colour.
The quality of the best inkjets can be very high and can be used for photographs.
Inkjet printers spray special ink on the paper to form characters and graphics.
The cost of replacing ink cartridges can be high with this type of printer because
they need replaced frequently. They print quite quickly, but can be quite slow
when printing graphics.
They are slower than laser printers.
Comparing printers
When we compare printers we should look at the following characteristics.

Set-up costs
This is a little tricky because it seems at first that inkjet printers are really
cheap. The initial cost or capital cost can be very low with a new inkjet printer
costing as little as £60. This is not the whole story because inkjets can have
expensive running costs.

Running costs
After you buy a printer these other costs become important. ‘Consumables’ (ink
refills, toner for laser printers, special paper) need to be bought regularly and
the cost of these varies from printer to printer. Colour inkjet cartridges can be
very expensive at around £20 each. Depending on how much printing you do
you can soon end up paying more for the ink than the printer itself!
The cost of repairs may also need to be considered for expensive printers.

Resolution
Resolution is measured in dots per inch (shortened to dpi). This is used to
measure the quality of the printout. Let us take the example of a resolution of
300 dots per inch. That means that for each square inch there are 300 x 300
dots = 90,000 dots. The higher the number of dots per inch the sharper and
clearer the image will be.

Speed
We should look at how long they take to print a page. Different printers have
different printing speeds. Measured in ‘pages per minute’ (ppm), faster printers
are normally more expensive and are often networked to allow many users to
take advantage of the speed.
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Comparison table
Printer
Set-up cost
Running cost
Speed
Resolution
Laser
High
Low
Fast
High
Colour laser
Very high
High
Fast
High
Inkjet
Low
High
Quite fast
Very high
LCD (liquid-crystal display)
These screens are flat, need only a small amount of power to run and can be
powered by batteries. They do not weigh as much as ordinary monitors. This
means they are ideal for use on laptops and palmtops. Liquid crystals work by
blocking light reflected from behind, so the screens cannot be read in the dark
unless they are backlit.
TFT (thin-film transistor)
TFT is a type of LCD screen that has more complex electronics than an ordinary
passive LCD. It uses arrays of transistors to control backlighting of the screen
actively. These enable it to display graphics and animations much more clearly and
quickly than an ordinary LCD and can display moving graphics without
‘shadowing’.
SOUND CARD
A sound card captures sounds and changes them into digital form: patterns of
binary numbers that are stored as files in your computer.
Sound card
When outputting sounds the sound card reverses the process and changes the
binary data held in the sound files into analogue signals that are used to
control the speakers attached to the computer. Speakers convert analogue audio
signals into the equivalent air vibrations in order to make audible sound. A pair of
speakers plugs into the computer’s sound card.
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More about capturing sound files
A microphone can be used to input sound. It converts sound waves into analogue
electrical waves. Usually called a ‘mike’, it contains a flexible diaphragm
composed of film or foil that vibrates as it makes contact with sound.
When capturing music, for example, a sound card takes thousands of samples of
the sound waves each second, turns the samples into patterns of binary numbers
and then stores them in files.
The process of taking thousands of samples and turning them into binary numbers
is very demanding on the main processor.
For example, if a system is sampling at the standard rate of 44.1 Khz and each
sample is stored as a 16-bit binary number then the processor has to convert and
store 441,000 16-bit binary numbers each second.
To make it easier for the system, a sound card has its own processor that relieves
the computer’s main processor of all of this extra work, which would slow it down.
Graphics card
Today’s applications use a lot of graphics. Even standard applications such as
spreadsheets run on operating systems with WIMP HCI. This means that all
applications need graphical items to run, such as windows, icons and drop-down
menus.
We also use multimedia and
presentation software that
incorporate graphics, animations
and even video.
Gaming software makes the
heaviest demands on the
graphics facilities of our
computers with its use of threedimensional graphics and realistic
animations.
Graphics cards are designed to
support the need for increasingly complex. graphics. Like sound cards, graphics
cards have their own processor dedicated to producing the graphics and relieving
the main system processor of the job.
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Graphics cards also have their own memory dedicated to handling the
graphic data, relieving the pressure on the system’s main memory. The
processor loads in the graphic file, which is made up of binary numbers,
and then outputs the graphic as a stream of signals to control the output on
the monitor.
Types of Backing Storage Featured on DVD
Backing storage devices are hardware that is used to store the programs and
data that the computer can access. Unlike RAM (or working) memory the
contents of backing storage will not be lost when power to the computer
system is turned off.
The three types of backing storage hardware we need to know are:
•
magnetic drive
– hard disk drive
– floppy disk drive
– magnetic tape drive

optical drive
– CD drive (ROM and RW)
– DVD drive (ROM and RW)

flash drive.
Hard disk drive
This is a type of magnetic backing storage. This means, as with a floppy disk drive,
it uses magnetism to encode and store data. Hard drives consist of stacks of nonremovable platters coated with magnetic materials – each with its own read/write
head. Hard disk drives are built into desktops and laptops.
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----------------------------------------------------------------------------------------------------------The key features of hard disk drives are:

They read and write data very quickly.

They can hold large quantities of data.
The capacity of a hard disk is measured in gigabytes. It holds much more
data than a CD-ROM. The capacity of a CD-ROM is measured in
megabytes. To find the capacity of the latest hard drive you should look in
the latest computer magazines or search the internet.
Hard disk drives use random/direct access to locate data stored on the disk.
Magnetic tape drive
This storage device is mostly used for backups because, although tape can store a
lot of data, it is slower to access. Having to wind through the tape when finding files,
would make it impracticable to use as the main storage device.
CD and DVD drives
Most software is now supplied on optical media such as CD-ROMs or DVD-ROMs.
CD-ROM
CD-ROM stands for: Compact Disk Read-Only Memory.
CD-ROM drives use a combination of lasers and sensors to read the data stored on
the surface of the disks. Like hard disk drives they use direct/random access to read
data.
CD-ROMs are read-only devices. They can hold in the region of 700 megabytes of
data.
DVD-ROM
DVD-ROM stands for Digital
Versatile Disk Read Only Memory.
A DVD-ROM drive is similar to a
CD-ROM drive in that it uses a
combination of lasers and sensors
to read the data. DVD-ROMs are
also read only.
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----------------------------------------------------------------------------------------------------------How are they different?
A DVD-ROM can store much more data than a CD-ROM. A single-sided singlelayer DVD-ROM can hold 4.7 gigabytes. There are double-sided DVD-ROMs
with several layers that can store up to 17 gigabytes.
What are they used for?
DVDs are mainly used for storing movies because the files needed to encode a
movie are very large indeed and are measured in gigabytes.
CD-Recordable (CD-R)
This is a CD similar to a CD-ROM. The difference is you can store data on the
CD-R. Standard CD-R disks hold 700 megabytes.
Using a laser and special dye in the disk a CD-Rewriter drive can store your
data on the CD. Once the data has been burned on to the disk you cannot
change it, it is read only.
CD-Rewriteable (CD-RW)
Like CD-R, these are compact disks on which you can store data using a CDRewriter drive. The main difference is that you can change the data later on if you
want to, just as you can on a hard disk.
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DVD-Recordable (DVD-R/DVD+R) 2
These are DVD disks that you can write to by using a DVD-Rewriter drive.
DVD-Rewriteable (DVD-RW/DVD+RW)
These are DVD disks that you can store data on over and over again, with a DVDRewriter drive. They use similar laser technology to CD-RW whereby the reflective
properties of the disk are altered to represent binary numbers.
DVD capacity
•
•
•
•
•
Single-sided/single-layer:
Single-sided/dual-layer:
Double-sided/single-layer:
Double-sided/mixed-layer:
Double-sided/dual-layer:
4.7 gigabytes of data – over 2 hours of video
8.5 gigabytes of data – about 4 hours of video
9.4 gigabytes of data – about 4.5 hours of video
13.24 gigabytes of data – about 6.5 hours of video
17 gigabytes of data – over 8 hours of video
USB backing storage devices
There is now a wide range of new storage devices that plug straight into the USB port
on computers. They can store from 8 MB up to (currently) 2 GB of data, and are a
simple and convenient way of backing up or transferring data.
Comparison of backing storage
The table below compares the storage capacity, access speed, portability and
media cost of different types of drive.
Drive
Capacity
Transfer
speed
Floppy
disk
Low
Slow
Hard disk
Very high
Tape
Portable
Drive cost
Media cost
√
Very low
Very low
Very fast
X
Low/medium
NA
Very high
Fast
√
High
High
CD
High
Fast
√
Low
DVD
Very high
Fast
√
Low/medium
USB Flash
Fast
High
√
Low/medium
-RVerylLow
-RW Low
-/+R Low
-/+RW Low
NA
2 DVD-R[W]
and DVD+R[W] are slightly different formats, but most new DVDRewriter drives can handle both types.
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This table features typical information from 2004 about actual drives. You can use
it to compare how prices, sizes and rates improve over time.
Drive
Capacity
Transfer speed
Drive cost
Media cost
Floppy disk
1.4 MB
0.04 Mbps
£5
10p a disk
Hard disk
100 GB
Approx 60000
FDs
100 Mbps
2500 x FDD
£50
NA
Tape
30 GB
Approx 20000
FDs
10 Mbps
250 x FDD
£370
£50
CD-RW
700 MB
Approx 500
FDs
30 Mbps
750 x FDD
£25
-R 13p
-RW 40p
DVD-RW
9 GB
Approx 6300
FDs
30 Mbps
750 x FDD
£70
-/+R £1.50
-/+RW £2.50
Flash
256 MB
Approx 200
FDs
1 Mbps
25 x FDD
£45
NA
MB = Megabytes
GB = Gigabytes
Mbps = Megabits per second
R
= Recordable
RW = Rewriteable
FD = Floppy disks
FDD = Floppy disk drive
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Sequential access to data
Sequential access means starting at the beginning of a sequence of data and
going through it one part after another until the computer finds the data it is looking
for.
A magnetic tape drive, often used for backing storage, is the best example of
sequential access. It starts at the beginning of the tape and has to wind forward
through the tape until it reaches the part it needs.
This takes time and is not suitable for many computer applications that demand
fast access to data.
Random or direct access
Hard disk drives, floppy drives, CD-ROM and DVD drives use direct or random
access. This means they go straight to the data they need. Unlike sequential
access tape drives, they do not have to go through all of the disk surface one part
after another to find the data.
Because it gives instant
access to the data, direct or
random access is used by
computer systems that need
to process data straight
away, unlike sequential
access, which takes time to
go through all the data in the
sequence.
Examples of use: updating
bank accounts as money is
taken out of a cash point
machine, booking seats on a
plane.
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Questions and Tasks
1.
2.
3.
Why do large businesses such as banks use mainframe computers?
Describe the components of the desktop computer you use in school or at
home.
Complete this table comparing a desktop with a laptop.
Desktop
Laptop
Output
Ordinary monitor
LCD/TFT
Backing storage
Hard disk, floppy disk,
CD/DVD drive
Power source
Mains power
Portable
No
4.
5.
6.
7.
8.
9.
10.
11.
12.
Name three types of software that run on palmtops.
Why are palmtops useful?
What is the typical capacity of a CD-ROM?
What are CD-ROMs used for?
What is the typical capacity of a DVD-ROM?
Why are DVD-ROMs used to store videos?
(a) What do CD-R and DVD-/+R have in common?
(b) In what way are they different?
(a) What do DVD-/+RW and CD-RW have in common?
(b) In what way are they different?
Complete this table comparing laser printers to inkjet printers. You
may have to search the internet to find out the relevant information.
© Learning and Teaching Scotland
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Computing Studies
Standard Grade
Computer Systems
----------------------------------------------------------------------------------------------------------Printer
Laser
Resolution Speed
make/model or inkjet (dpi)
(ppm)
Initial
purchase
cost
Cost of the
ink/toner
HP Deskjet
9300
Inkjet
4800 x
1200 dpi
7 ppm
£260
2.65 pence per
mono page
7.1 pence per
colour page
Epson
Aculaser
C900
Colour
laser
600 x 600
16 ppm
£679
1.5 pence per
mono page
6.7 pence per
colour page
Inkjet
Laser
Inkjet
Laser
13.
14.
15.
16.
17.
18.
19.
20.
21.
What is the difference between an LCD screen and a TFT screen?
What features of LCD/TFT screens make them suitable for use on laptops?
Why is a trackpad suitable for controlling the pointer on a laptop?
Why do you think the combination of a keyboard and mouse is used as
a means of inputting data into a desktop?
Describe a graphics tablet.
Who uses a graphics tablet?
How does a digital still camera work?
List four advantages of digital cameras.
Use the internet or the latest magazines to get information on four of the
latest digital cameras and then complete the following table.
Name and make
of camera
Memory capacity
© Learning and Teaching Scotland
Number of
megapixels
Editing features
25
Computing Studies
Standard Grade
Computer Systems
----------------------------------------------------------------------------------------------------------22.
How does the storage capacity of a digital video camera differ from that
of a digital still camera?
23. In what way is a digital video camera the same as a digital still camera?
24. How does a webcam operate?
25. Use a search engine to find a list of webcam sites and check some out for
yourself, then complete the following table.
Webcam address
Webcam used for:
www.
26.
27.
28.
29.
30.
31.
32.
What is the difference between sequential and random/direct access to
data?
Which types of backing storage uses random/direct access to data?
How does a sound card capture sounds?
Search for two sound cards on the internet or in a computing magazine and
write up a short report on each one.
Why do computers need graphics cards?
Why do graphics cards have their own processor and memory?
Use the internet to search for graphics cards. Pick two and write a short
report on their main features.
© Learning and Teaching Scotland
26
Computing Studies
Standard Grade
Computer Systems
-----------------------------------------------------------------------------------------------------------
Answers to Questions and Tasks
1. Because they:
 have very powerful processors
 have a large amount of backing storage
 are designed to process large volumes of data at high speeds.
2. Mention the monitor, the processor, the memory and backing storage as well
as any peripherals attached to it.
3.
Desktop
Laptop
Output
Ordinary monitor
LCD/TFT
Backing storage
Hard drive, CD/DVD
drive
Possibly all three,
depending on the model
you chose
Power source
Mains power
Main or battery
Portable
No
Yes
4. Simple word processing, database and spreadsheet software as well as
useful applications such as electronic mail.
5. Because they are compact and can fit in your pocket. They can run a
range of software and the latest versions enable you to access the internet
and connect with your LAN.
6. 700 megabytes
7. Storing large files that do not need to be updated, for example encyclopaedias,
software, games.
8. A single-sided DVD will hold 4.7 gigabytes. A double-sided double-layered DVD
will hold four times that amount.
9. Because of their large capacities.
10.(a) You can write data to them once. They both use laser technology.
(b) DVDs have a much higher capacity.
11.(a) You can write data to them over and over again. They both use laser
technology.
(b) DVDs have a much higher capacity.
12. Completed table comparing laser printers to inkjet printers.
13. A TFT screen uses more complex electronics, an array of transistors, to control
backlighting of the screen. The result is that it gives a clearer image than an
ordinary LCD screen and displays moving graphics without ‘shadowing’.
© Learning and Teaching Scotland
27
Computing Studies
Standard Grade
Computer Systems
----------------------------------------------------------------------------------------------------------14. They are compact and light.
15. Because you can operate it without the need for a mouse or a flat surface like a
desk. This makes it ideal when you are on the move.
16. Because they complement each other. The keyboard is used to enter text and
keyboard shortcuts. The mouse is used to control the pointer and select icons
and items on menus.
17. It has a flat surface that can sense the slightest movement. Artists and
designers use it to enter drawings into a computer system. By dragging a stylus
across the tablet surface you can draw freehand and the drawing is entered
exactly into the computer’s memory.
18. An artist or designer who needed to enter freehand drawings.
19. A digital camera takes photographs by using sensors to capture the light that
comes in through the lens. It then converts the light into binary numbers that
are recorded on backing storage. This digital version of the photograph can then
be displayed on the small screen that is set into the camera.
20 ▪They can hold lots of photos without the need to buy film.
▪You can see what your photo is like straight away and you can delete any
you do not want.
▪The photos are digital so you can transfer them to your PC and then do all
sorts of things with them such as: edit them, print them, store them on a
writeable CD, attach them to an e-mail.
▪ You do not need to have them developed, saving time and money.
21. Completed table with name and make of camera, memory capacity, number
of megapixels and any editing features.
22. They tend to have much larger storage capacities because of the size of
the video files.
23. They both operate in basically the same way.
(a) They use light sensors to capture the images.
(b) The images are then changed into binary numbers.
(c) The binary numbers are then recorded in files on the cameras
backing storage.
24. A webcam uses technology for capturing the images that is similar to that used
in the other digital cameras. Webcams are used to take photos and then send
them across the internet. Webcams transmit photographs that are regularly
updated at various speeds from one every few minutes to full streaming video.
25. List of webcam sites with a description of what the webcam is used for.
26. Sequential access to data involves the system going through blocks of data
one after another, in turn , before accessing the item of data required. Using
random/direct access a system can go directly to the data required.
27. Hard disks, floppy disks, CD-ROMs, CD-R, CD-RW and all DVDs.
28. It takes thousands of samples of the sound waves each second, turns the
samples into patterns of binary numbers and then stores them in files.
29. The answer to this will depend on your search.
30. Because the latest software uses increasingly complex graphics, including
3-D graphics and animations.
31. They need their own onboard processor to relieve the main processor of the
burden of handling all the graphics. Similarly, they need lots of onboard,
dedicated memory to free the computer’s main memory of the need to store
the very large graphics files that are being processed.
32. The answer to this will depend on the results of your internet search.
© Learning and Teaching Scotland
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