Input and Output Devices
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
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.
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
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
Definitions Input device: A hardware device used to input data into a computer system for processing
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)
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
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
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
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
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.
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
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 10 m • Used in – – – Shops to prevent shoplifting Track luggage at airports Tags on animals Toll booths for motorists & car parks Libraries
RFID Tags – how many have you seen?
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
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
Definitions Output device: A hardware device used to communicate the results of data processing carried out by a system
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
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) • 3 D printing becoming more economical • Architects use large format plotters to produce plans
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
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)
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.