A Level Computer Science Paper 1: 1.1.3 Input and Output Devices

Input devices that require greater human intervention

Tend to be used for products
UPC-A
Universal Product Code version ‘A’ retail/warehousing
Code 128 transport/shipping

Tend to be used for website links etc

Patterns of squares to link a website/information

Allow for data to be obtained directly without user input. Take measurements of physical properties from real world surroundings

Data has no constant value - the data changes smoothly rather than in exact jumps

light, temperature, pressure, humidity

Monitoring sees the sensor taking a measurement and reporting a value but not making a change. Control changes it

Analogue to digital convertor - puts signals in a format that a computer can understand (binary)

Digital to analogue convertor - means people can understand it

Take data produced by a computer and turn it into human-readable form

The circuit sends data to tell the printer what jets of ink to heat up and burst the bubbles to each part of the paper
Often used for photographs

+You can combine colours, high quality
+ cheaper than laser
-if you have a shared cartridge, one colour running out means the whole cartridge needs replacing

Instructions are sent where a drone rolls beside a roller with toner attracting paper onto the roller as paper comes past to roll the toner onto it
E.g. labels/brochures/fliers

+ much quicker than ink-jet

- more expensive than ink-jet

Strike an inked ribbon which imprints dots to form letters on the page
e.g printing in a dusty warehouse

+ useful where multi-part stationary is required
+ can work in damp/dirty atmosphere
- can’t be used for images/colour
- noisy

Print using plastic filament, powdered resin, ceramic/metal powder or paper to make intricate objects including hollow areas

Radio frequency ID
Powered receiver emits radio frequency energy, transponder becomes energised and sends data
e.g. contactless payment, security, ID

No power source, rely on radio waves from receiver for energy, transponders must be close
E.g. contactless payment

Use a large battery powered beacon, 300m broadcast range

E.g. tracking products in a supermarket

Motors used in conjunction with sensors to control a machine

e.g. automatic doors

Data sent from computer to DAC, boosted by an amplifier and sent to a speaker

Liquid crystal display screens
Contain groups of RGB diodes to form each pixel
Require backlighting with cold cathode fluorescent lights- CCFL

Used instead of CCFL in LCD monitors

Cheaper, lighter, brighter, quicker, less likely to break

Organic LED
Use plastic rather than glass - flexible
Much brighter than LCD/LED
Generate their own light
Use much less power, less heat (lower fire risk)

Compact, high-resolution full colour projectors

| Project text, images, video and audio contenting