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Input & Output DevicesInput & Output Devices
An input device captures data and sends it to a computer system.
Input devices convert physical movement, such as key pressing, or environmental data, such as temperature, sound or light into electrical signals.
Input DevicesInput Devices
There are two types of input device: manual andautomatic.
Manual Input DevicesManual Input Devices
A manual input device requires a human hand tocontrol it…
Mouse
Keyboard
Scanner
Camera
Manual Input DevicesManual Input Devices
Tracker ball
Joystick Graphics tablet
A manual input device requires a human hand tocontrol it…
Manual Input DevicesManual Input Devices
Keyboard
The most common input device
You press keys to input data into the computer
The most common type of keyboard is the QWERTY keyboard
People are familiar with keyboards, so they don’t need to be trained
Skilled typists can work very quickly
A lot of different keyboards are available, e.g. ergonomic
They are very reliable and cheap
Incorrect use or over-use can cause RSI
Many people cannot type and look at the screen at the same time, so typing can be time consuming
Uses Advantages DisadvantagesDevice
Manual Input DevicesManual Input Devices
ConceptKeyboard
Simplified keyboard used in fast food restaurants and other businesses, where a waterproof keyboard and simplified choices makes serving customers much quicker
Used on computer-style toys for small children
Very quick and simple to use
Overlay can be wiped clean easily
Overlay makesthe keyboard waterproof, so safer for food restaurants
Have to changethe overlay sheet, when the menu changes
You would need to increase the number of keys to increase the number of options, so not very flexible
Uses Advantages DisadvantagesDevice
Manual Input DevicesManual Input Devices
GraphicsTablet
A graphics tablet consists of a pad and a special pen
It allows artists and graphic designersto draw naturallyas though theywere drawingon paper
The image is instantly converted to digital data
User can get much more control, similar to the natural way of drawing
Advanced models detect subtle changes in pressure, to enable thicker lines to be drawn
The user can zoom in to an area of the drawing for higher accuracy
Large models are very expensive
Need a large desk area
Holding a pen for a long time is more tiring than holding a mouse
Uses Advantages DisadvantagesDevice
Manual Input DevicesManual Input Devices
Mouse
Most common pointing device
Used to point and click on icons or menus
Combines well with a keyboard
Fast and accurate
Most people are skilled at using a mouse, so no training is needed
Prolonged use can lead to RSI
Need a flat surface to use them
For an optical mouse, the laser does not work wellon all surfaces
Tracker ball
A tracker ball is basically an upside down ball mouse.
The user runs their thumb over the ball to control the on-screen pointer
User can get great pointing accuracy, without moving the hand
Useful where desk space is limited
Some people find that the thumb gets painful with prolonged use
Ball can get greasy and dirty
Uses Advantages DisadvantagesDevice
Manual Input DevicesManual Input Devices
Uses Advantages DisadvantagesDevice
Scanner
Used to convert printed images or text into a file of digital data
There are two types: handheld and flatbed
Even cheap scanners produce quality images
Any printed image can be inserted into a document
Images can be edited before use
Pictures can use a lot of memory
The quality of the final image is dependent on the original image
Issues of copyright protection
Joystick Originally designed forpilots to control aeroplanes
Used to control wheelchairs and for playing games
They give a more realistic gaming experience when playing games such as flight simulators
Many different types available
Some people find them difficult to operate, especially in 3-d environments
Manual Input DevicesManual Input Devices
Digital Camera
Used for taking still images which can be uploaded to a computer for permanent storage
You can preview the image before pressing the shutter button
No film needed or development costs
Unwanted images can be deleted
When the drive is full, images need to be uploaded to a computer or deletedHigh resolution camera does not guarantee good images
Touchpador
Fingerpad
A pointing device, built into a laptop for convenience
Portable - built into the laptop
Don’t need to carry extra equipment around
Small movements needed to move the cursor
Takes practice to master
Some people find them very fiddly
Fingers need to be clean and free of grease
Uses Advantages DisadvantagesDevice
Automatic Input DevicesAutomatic Input Devices
An automatic input device inputs data without the need for human intervention (once the device has been set up), e.g. MICR, OMR, barcode reader, webcam, microphone, sensor.
Microphone
Webcam
Barcode reader
Automatic Input DevicesAutomatic Input Devices
MICR
MagneticInk
Character Recognition
Banks print important data on the bottom of cheques using magnetic ink
This ink is then read by a computer
Very quick and accurate processing of data – very low error rate. Humans could not achieve the same accuracy
Very secure as any attempt to change the numbers on a cheque will be ignored as the reader only recognises magnetic ink in the same font
Expensive to produce and print magnetic ink, and the reader is also expensive
Banks are the main user – very few other applications
Uses Advantages DisadvantagesDevice
Automatic Input DevicesAutomatic Input Devices
OMROpticalMark
Recognition
Used when youmark the numbers with a pencil ona lottery ticket
Also used to mark multiple choice exam papers, and paper-based school registers
Very fast method of reading data, which reduces queuing time for lottery tickets
More accurate than humandata entry
Sometimes incomplete marks are not read correctly
Only pre-prepared forms can be scanned into the computer
Uses Advantages DisadvantagesDevice
OCR Optical
CharacterRecognition
Uses a scanner to scan text, then software converts the text into a word processor file
Used to read post codes, as part of the sorting process
Quicker than typing in the text
Latest software can recognise tables and even handwriting
Reduces the cost of posting a letter
Sometimes it is not very accurate
Documents need to be proof-read after scanning
Only worth doing for large amounts of text
Automatic Input DevicesAutomatic Input Devices
Barcode Readers
Used to identify products in shops
The code is read by a barcode scanner which identifies the product name, manufacturer and country of origin
Very quick and accurate way to enter data – suits busy shops
Prices changes are made on the database, not the barcode – more flexible system
All barcodes need to be programmed into the computer in advance
The reader maynot be able to readthe barcode on wrinkled packaging
Uses Advantages DisadvantagesDevice
Magnetic Stripe
Reader
Found on the back of bank cards and store loyalty cards
The stripe holds information, suchas the account number and the PIN
Simple, cheap and effective
The data on the card can be altered if needed
‘Chip n’ Pin’ has increased security
Magnetic stripe can get scratched Not much data can be storedThieves can read data on cards then use the cards themselves
Uses Advantages DisadvantagesDevice
Microphone
Used to input sound into the computer
Used to give the computer commands, or to dictate letters directly to a word processor
Very cheap piece of equipment
Helpful for people with additional needs or for busy people who need very quick letters
Computer can misread voice instructions due to natural variations in people’s voices
Generally, the sound quality from a PC microphone is poor
Automatic Input DevicesAutomatic Input Devices
Webcam Used to input moving images into the computer for use in online communication
Very cheap piece of equipment
Enables people to see each other whilst they chat
The image quality from most webcams is poor
The moving picture tends to flicker due to current limitations in data transfer
Output DevicesOutput Devices
Output DevicesOutput Devices
An output device is used to display or use information that comes out of a computer system.
Output devices convert electrical signals from a computer system into…
Sound (speakers or headphones) Images & Text (screen or printer) Movement (actuator, electric motor)
Output DevicesOutput Devices
Monitor Speakers
Plotter
Headphones
Printer
Output DevicesOutput Devices
TFT Monitor
Thin Film Transistor monitors are more commonly known as flat screens or LCD screens
Take up very little space
Run very quietly and produce little heat
Use about a third of the energy ofa CRT monitor
Easy to damage
Colour contrast on cheaper models is not as good as CRT monitors
You may get ‘dead’ pixels
Uses Advantages DisadvantagesDevice
CRT Monitor
Cathode Ray Tube is very old technology.Almost completely replaced by flat screen monitors
Robust and difficult to damage
Reliable
Last for a very long time
Large, bulky and unsightly
Can be heavy
Produce a lot of heat
Old technology
Output DevicesOutput Devices
Speakers&
Headphones
When connected to a computer through a sound card, music can be played
Gives feedback to user during general computer use
Can help blind people use the computer
A presentation can be more powerful with sound
Games are a lot more involving and realisticwith sound
Speakers are not useful in a network room, as everyone would disturb each other
Headphones can be uncomfortable with extended use
Uses Advantages DisadvantagesDevice
Plotter These are specialist printers that can produce high quality printoutson large piecesof paper
Very high quality printouts
Almost any size paper can be used
Slower than normal printers
Expensive to purchase and run
PrintersPrinters
There are 3 main types of printer…
Dot Matrix
Laser
Inkjet
Uses Advantages DisadvantagesDeviceGeneral purposeuse for family orhome office
Cheap to buy
Latest modelscan be very fast
Ink cartridges can be very expensive
Print quality not always very good
Business use for letters,stationery and images
Quality printing
Good for large areas of colour
Quiet & Quick
More expensive to buy than inkjets
Toner cartridges are expensive
Business usefor duplicatedocuments
Can make a carbon copyCan print on continuousrolls of paper
Noisy and rather old-fashioned technology
Poor quality and only prints in black ink
Drag the input and output devices to the correct side...
Input & Output DevicesInput & Output Devices
Keyword ActivityKeyword Activity
Drag the missing words to the correct place in the sentences…
Input Device WordsearchInput Device Wordsearch
Output Device WordsearchOutput Device Wordsearch
Input Device CrosswordInput Device Crossword
Output Device CrosswordOutput Device Crossword
QuizQuiz
After viewing this presentation, you should…
Know that an input device allows you to input data into a computer system.
Understand when to use different input and output devices.
Know that an output device allows you to view or use information from a computer system.
Be able to describe the advantages anddisadvantages of a wide range of input and outputdevices.
Objectives
Know the difference between a manual input device and an automatic input device.
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