1. Input and Output
Devices

2. Lesson Objectives Understand the need for input and output devices
Describe suitable input devices for a wide range of computer controlled situations
Describe suitable output devices for a wide range of computer controlled situations
Discuss input and output devices for users with special needs

3. Definition of a System - Recap
A system is a collection of parts that work together for a common purpose. It needs to receive and process inputs in order to produce outputs.

4. Early input & output devices
Early computers used punched cards (or tape) for input
Data was read by recording if light was passing through the holes onto an array of sensors
Output was sent to an electronic typewriter

5. Modern input/output devices
Not just limited to a modern laptop, desktop or handheld device
Includes specialised systems used in a variety of applications e.g.:
Washing machines
Microwave ovens
Central Heating controllers
Need to be appropriate for situation so system functions effectively

6. Definitions
Input device: A hardware device used to input data into a computer system for processing

7. Input devices: Keyboard
A device that uses labelled keys to enable data input to a computer
Qwerty keyboard (external)
On screen keyboard (internal)
Braille keyboard (blind/partially sighted users)

8. Input devices: Mouse
A device that controls the movement of a pointer on the screen based on its own movement, and allows the user to select an object by pressing a button
Invented in 1963
Early ones had wheels or track ball
Optical mouse most common now
Graphics tablet
A graphics tablet consists of a flat pad (the tablet) on which the user draws with a special pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet a designer can produce very accurate on-screen drawings as if they were drawing on paper.

9. Input devices: Touch screen
A touch sensitive surface that allows the user to select, control or move objects by touching icons and symbols using fingers
Used in tablets
Mobile phones
Kiosks
Supermarket checkouts
Touchpad – earlier incarnation
Touch sensitive pad
More hardwearing & resistant to damage
E.g. garages, fast food outlets

10. Input devices: Microphone
A device for capturing sound
Used for inputting speech, communication & voice commands
Voice input is often used by disabled users to control computer systems

11. Input devices: Camera A device to capture still and moving images
Most modern laptops, tablets and mobile phones have an integrated camera
External cameras include webcams
Also used for video conferencing (e.g. Skype)
Cameras can be used for facial or iris recognition for security applications

12. Input devices: Scanner
A device to digitise hard copy documents and images
They're similar to a photocopier but they make a digital copy instead of a physical copy.
They can also be used with optical character recognition (OCR) software to scan in text that is then editable.

13. Input devices: Barcode scanner
A barcode is pattern of thin and thick lines representing a number that can be scanned by a reader for input to a computer system
QR codes are similar (2 dimensional) – can hold more data

14. Input devices: RFID reader
RFID: Radio frequency identification uses radio frequencies to represent a number that can be scanned into a computer system
Electronic version of barcode
Don’t need line of sight; can be read up to 10m
Used in
Shops to prevent shoplifting
Track luggage at airports
Tags on animals
Toll booths for motorists & car parks
Libraries

15. RFID Tags – how many have you seen?

16. Input devices: Sensors
A device that can detect physical conditions such as temperature, weight, light, sound etc.
Other sensors types
Pressure
Accelerometers (used in handheld games and mobile phones)
Motion sensors
Gesture based interfaces use motion sensors (e.g. Kinect)
Sensors are found in computer control
Most modern aeroplanes use range of sensors to detect factors
Provides automatic feedback to a control system which then responds accordingly

17. Input devices for users with specific needs
A range of adapted devices for those with different requirements
Eye-typer
Uses camera to track eye movements & detects which key looking at
Puff/suck switch
Switch operated by blowing/sucking small tube. Special software determines actions to take
Voice input
Head wand
Joystick
Foot-mouse
Braille Keyboard

18. Definitions
Output device: A hardware device used to communicate the results of data processing carried out by a system

19. Output devices: Monitor
A device that can display images and text
LCD and LED monitors most common
CRT monitors are still in use
Hand held devices use touch screen display so input and output are through same device

20. Output devices: Printer
A device to produce physical copies of output from a computer system
Laser printers (fast & economical but expensive to buy)
Ink jet (cheap to buy, high quality photographs)
Dot matrix printers are not so common today. (noisy and low quality but are cheap ; used when carbon copies or duplicates need to be made, such as for wage slips. Much sturdier )
Thermal printers (supermarket checkout till receipts – silent, no moving parts)
3D printing becoming more economical
Architects use large format plotters to produce plans

21. Output devices: Speakers
A device to output sound
Playing music
Visually impaired rely on speakers/headphones for feedback
Sound output can also be warning beeps

22. Output devices: Actuators
A device to produce physical movement based on out put from a computer system
Fundamental part of aeroplane control system
Sensors monitor various factors (input)
The actuators modify the behaviour of components (e.g. wing flaps) based on calculations of the system (output)

23. Output devices for users with specific needs
Screen readers (for visually impaired) eg
Magnification
Speech output
Read text and convert to Braille
Actuators
Create physical movement to a computer command
Voice synthesisers
Spoken output from a a computer can be used for those unable to communicate verbally.