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 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.

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 10m 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) 3D 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.