GCSE All the revision for ICT exam aqa

Notes on the aqa specification of ICT

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  • Created on: 19-12-11 15:32
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ICT Revision
1. Hardware
Input devices: Used to put or send data and information from the computer,
There are 2 types of input devices, manual and automatic.
Manual input devices
QUERTY Keyboard the standard keyboard
Braille Keyboard for people who are visually impaired, this consists of letters and symbols
that are read similar to Braille.
Advantages Disadvantages
Most computers come supplied with one. It's easy to make mistakes when entering
Using keyboards requires very little training. data.
Skilled typists can enter data very quickly. If you cannot touch type it can be very time
Specialist keyboards are available, ergonomic consuming to enter data.
and gaming keyboards are used to make it Keyboards are not suitable for creating
more comfortable to enter data. diagrams.
Disabled people can find them difficult to use.
Excessive use can lead to RSI.
Concept Keyboard consists of a flat panel of contact switches covered by a flexible
membrane, a pictorial keyboard which you can press to enter data. They are used in
restaurants, primary schools and in hostile environments like on an oil rig to protect the
keyboard from being damaged.
Advantages Disadvantages
Much faster in businesses like restaurants Poor for text or numeric input.
for entering data for the consumer quickly. Can get dirty.
It is waterproof, making it useful in You need to change the pictures or inputs when
environments like on an oil rig. a product changes. Therefore it's limited to the
options shown on the keyboard.
Mouse enables you to control what happens on the screen using the pointer, most mice are
optical meaning that they use a light beam and detector.
Advantages Disadvantages
Ideal for use on a desktop computer. You need a flat space near to the
Usually supplied as part of a new computer system. computer.
Most computer are used to them require little The rollers in the mouse can become
training. clogged and so the mouse becomes less
They work well with the keyboard for data entry. accurate until cleaned.
Overuse can lead to RSI.

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Tracker ball very similar to a mouse but the ball its set into a cup on the top of the unit.
Advantages Disadvantages
Ideal for use when flat space next to the computer is limited. Not supplied as standard.
Joystick similar to a tracker ball except instead of a ball a stick is used. They are used in
gaming, aeroplane controls, controlling machines such as wheelchairs and cranes.…read more

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Graphics tablet produces accurate drawings than a mouse or pointing device.
Advantages Disadvantages
Easier to use because it's much more Only suitable for inputting diagram data.
natural to use than a mouse. Can be very difficult to use.
Very accurate. Very expensive.
Microphone used to input sound.
Advantages Disadvantages
With voice recognition software it is very easy
Some systems need to be trained to
to use. understand a different voice.…read more

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Converter) must be connected between the computer and the sensor. This device converts the
analogue signals from the sensor into digital data that the computer can process.
Output devices: Used to display the data and information from the computer.
Monitors or VDU (Visual Display Unit) the most common output device. There are many
different types of screens
A CRT (Cathode Ray Tube) is becoming very outdated, because they are large and bulky
and have a glass screen.…read more

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Fast printouts Toner is more expensive than the inkjet cartridges.
Prints very quietly Bulky
Cost per page is low Can't use continuous or multipart stationary to create carbon copies.
Inkjet printers very popular because they are cheap. They use ink cartridges to produce
both black and white and colour copies.…read more

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Switches can turn electrical equipment `on' or `off' and can operate valves to control the flow
of air and fluid through pipes.
LEDs (LightEmitting Diodes) can be connected to the computer and respond to electric
signals which tell them to switch on and off.
Actuators Signals from computers can generate physical movement in certain control devices.
These devices are called actuators and include motors, hydraulics and pneumatics.…read more

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When the computer is turned on it boots up
It links the operating system to the memory.
Remembers the instructions, this is called nonvolatile memory.
Stored on a chip, and so not lost.
RAM (Random Access Memory)
Bigger the memory, the larger the workspace to load.
When you switch off the computer the RAM is cleared, wiped, this is called volatile memory.
Backup Storage
Hard Disk data is stored by magnetising the surface of a flat, circular plate.…read more

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Multi program, e.g. you using 3 applications at once words, access, excel.
Multi user, e.g. network
Batch, e.g. accepts a list of jobs, input wages and then processes in one go, all payroll
Real time processing e.g. airline reservation immediate response or blocks others from
using same seats.
Computer User Interfaces
Command Line Interface (CLI)
It's possible to give the computer instructions without the help of a menu.…read more

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Advantages Disadvantages
Easy to use Take up a lot of RAM
Don't need to remember commands Take up a lot of processing to refresh
Interface is familiar with each application displays
Sound and Speech Interface
Allows you to interact with your environment or device by speaking the commands.
Used in modern cars to listen to the radio or answer a phone call whilst driving.…read more


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