COMPUTER SYSTEMS
Thanks to Dorothy Tedman for her contribution to the review of the content.
First published 2004
© Learning and Teaching Scotland 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 ii STANDARD GRADE COMPUTING STUDIES
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COMPUTER SYSTEMS
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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.
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
Main aspect
Operating systems
F/G/C G/C C
• sequential and random/direct access to data
Low-level machine
• megabyte (MB), gigabyte (GB)
Hardware • backing storage
• desktop, laptop/notebook, palmtop
• current input devices
• current output devices
• current backing storage devices
• capacity of backing storage
• mainframe • sequential and random/direct access devices input devices • mouse
(Computer
Systems)
• trackpad
• graphics tablet
• touch-sensitive screen • microphone
• sound card
• digital still camera • use of a variety of
• digital video camera
• webcam input devices for multimedia
• keyboard output devices • printer:
(Computer
Systems)
– laser
– inkjet
• monitor (VDU)
Comparison of • use of variety of
Printers in terms of: output devices
– speed (ppm)
– capital costs
– running costs
– resolution (dpi) for multimedia
• sound card
• graphics card
Backing storage • magnetic tape
(Computer
Systems)
• floppy disk
• CD-ROM
• DVD-ROM
• 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
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COMPUTER SYSTEMS
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.
A personal computer (PC) is a computer that is small and cheap enough to be owned and/or used by a single person.
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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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.
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.
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.
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 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).
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 gigabyte 1 of information.
1 Gigabyte: a unit of information equal to one billion (1,073,741,824) bytes or 1024 megabytes
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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.
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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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.
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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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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• 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.
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.
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.
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 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.
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:
• set up videoconferencing
• monitor traffic
• advertise tourist sites
• advertise businesses.
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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.
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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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.
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 vary 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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Printer
Laser
Set-up cost Running cost Speed
High Low Fast
Colour laser Very high High
Inkjet Low High
Fast
Resolution
High
High
Quite fast Very high
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 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’.
A sound card captures sounds and changes them into digital form: patterns of binary numbers that are stored as files in your computer.
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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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 the 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.
Today’s applications use a lot of graphics. Even standard applications such as spreadsheets run on operating systems with a 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 three-dimensional 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.
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
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 non-removable 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.
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.
Most software is now supplied on optical media such as CD-ROMs or DVD-ROMs.
CD-ROM stands for: C ompact D isk R ead -O nly M emory.
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 stands for D igital
V ersatile D isk R ead O nly
M emory
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 single-layer 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.
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.
Like CD-R, these are compact disks on which you can store data using a CD-
Rewriter 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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+
2
These are DVD disks that you can write to by using a DVD-Rewriter drive.
+
These are DVD disks that you can store data on over and over again, with a
DVD-Rewriter drive. They use similar laser technology to CD-RW whereby the reflective properties of the disk are altered to represent binary numbers.
• Single-sided/single-layer: 4.7 gigabytes of data – over 2 hours of video
• Single-sided/dual-layer: 8.5 gigabytes of data – about 4 hours of video
• Double-sided/single-layer: 9.4 gigabytes of data – about 4.5 hours of video
• Double-sided/mixed-layer: 13.24 gigabytes of data – about 6.5 hours of video
• Double-sided/dual-layer: 17 gigabytes of data – over 8 hours of video
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.
The table below compares the storage capacity, access speed, portability and media cost of different types of drive.
Drive Capacity Transfer speed
Portable Drive cost Media cost
Floppy Low disk
Slow
Hard disk Very high Very fast
3
U
Very low Very low
Low/medium NA
Tape
CD
DVD
Very high Fast
High Fast
Very high Fast
3
3
3
High High
Low R Very low
RW Low
Low/medium -
/ +
R Low
/
+
RW Low
USB
Flash
High Fast 3 Low/medium NA
2 DVD-R[W] and DVD+R[W] are slightly different formats, but most new DVD-Rewriter 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
Floppy disk 1.4 MB
Hard disk
Transfer speed Drive cost Media cost
0.04 Mbps £5
£50
10p a disk
NA
Tape
CD-RW
100 GB 100 Mbps
Approx 60000 2500 x FDD
FDs
30 GB 10 Mbps
Approx 20000 250 x FDD
FDs
700 MB
Approx 500
FDs
30 Mbps
750 x FDD
£370
£25
£50
-R 13p
-RW 40p
DVD-RW
Flash
9 GB
Approx 6300
FDs
256 MB
Approx 200
FDs
30 Mbps
750 x FDD
1 Mbps
25 x FDD
£70
£45
-/
+
R £1.50
-/
+
RW £2.50
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 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 a 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.
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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1.
Why do large businesses such as banks use mainframe computers?
2.
Describe the components of the desktop computer you use in school or at home.
3.
Complete this table comparing a desktop with a laptop.
Desktop Laptop
Output
Backing storage
Ordinary monitor
Hard disk, floppy disk,
CD/DVD drive
LCD/TFT
Power source
Portable
Mains power
No
4.
Name three types of software that run on palmtops.
5.
Why are palmtops useful?
6.
What is the typical capacity of a CD-ROM?
7.
What are CD-ROMs used for?
8.
What is the typical capacity of a DVD-ROM?
9.
Why are DVD-ROMs used to store videos?
10.
(a) What do CD-R and DVD-/
+
R have in common?
(b) In what way are they different?
11.
(a) What do DVD-/
+
RW and CD-RW have in common?
(b) In what way are they different?
12.
Complete this table comparing laser printers to inkjet printers. You may have to search the internet to find out the relevant information.
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Printer Laser or Resolution Speed Initial make/model inkjet (dpi)
Cost of the
(ppm) purchase ink/toner cost
HP deskjet Inkjet
9300
Epson
Aculaser
C900
Colour laser
4800 x
1200 dpi
600 x 600
7 ppm £260
16 ppm £679
2.65 pence per mono page
7.1 pence per colour page
1.5 pence per mono page
6.7 pence per colour page
Inkjet
Laser
Inkjet
Laser
13.
What is the difference between an LCD screen and a TFT screen?
14.
What features of LCD/TFT screens make them suitable for use on laptops?
15.
Why is a trackpad suitable for controlling the pointer on a laptop?
16.
Why do you think the combination of a keyboard and mouse is used as a means of inputting data into a desktop?
17.
Describe a graphics tablet.
18.
Who uses a graphics tablet?
19.
How does a digital still camera work?
20.
List four advantages of digital cameras.
21.
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
Number of megapixels
Editing features
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22.
How does the storage capacity of a digital video camera different 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 www.
Webcam used for:
26. What is the difference between sequential and random/direct access to data?
27. Which types of backing storage uses random/direct access to data?
28. How does a sound card capture sounds?
29. Search for two sound cards on the internet or in a computing magazine and write up a short report on each one.
30. Why do computers need graphics cards?
31. Why do graphics cards have their own processor and memory?
32. Use the internet to search for graphics cards. Pick two and write a short report on their main features.
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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.
Output
Backing storage
Desktop
Ordinary monitor
Hard drive, CD/DVD drive
Laptop
LCD/TFT
Possibly all three, depending on the model you chose
Power source
Portable
Mains power
No
Main or battery
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 doublelayered 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’.
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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.
STANDARD GRADE COMPUTING STUDIES 23
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COMPUTER SYSTEMS
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 the result of 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.
24 STANDARD GRADE COMPUTING STUDIES
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COMPUTER SYSTEMS
STANDARD GRADE COMPUTING STUDIES 25
© Learning and Teaching Scotland

COMPUTER SYSTEMS
26 STANDARD GRADE COMPUTING STUDIES
© Learning and Teaching Scotland