Input Output Devices Input Devices An input device

Input & Output Devices

Input 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. § There are two types of input device: manual and automatic.

Manual Input Devices § A manual input device requires a human hand to control it… Keyboard Mouse Camera Scanner

Manual Input Devices § A manual input device requires a human hand to control it… Tracker ball Joystick Graphics tablet

Manual Input Devices Device Uses The most common input device You press keys to input data into the computer Keyboard The most common type of keyboard is the QWERTY keyboard Advantages Disadvantages People are familiar Incorrect use or with keyboards, so over-use can cause they don’t need to RSI be trained Many people cannot Skilled typists can type and look at the work very quickly screen at the same time, so typing can A lot of different be time consuming keyboards are available, e. g. ergonomic They are very reliable and cheap

Manual Input Devices Device Uses Simplified keyboard used in fast food restaurants and other businesses, where a waterproof Concept keyboard and Keyboard simplified choices makes serving customers much quicker Used on computerstyle toys for small children Advantages Very quick and simple to use Overlay can be wiped clean easily Overlay makes the keyboard waterproof, so safer food restaurants Disadvantages Have to change the 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

Manual Input Devices Device Uses A graphics tablet consists of a pad and a special pen Graphics Tablet Advantages User can get much more control, similar to the natural way of It allows artists and drawing graphic designers to draw naturally Advanced models as though they detect subtle were drawing changes in on paper pressure, to enable thicker The image is lines to be drawn instantly converted The user can zoom to digital data in to an area of the drawing for higher accuracy Disadvantages Large models are very expensive Need a large desk area Holding a pen for a long time is more tiring than holding a mouse

Manual Input Devices Device Mouse Uses Advantages Disadvantages Most common pointing device Combines well with a keyboard Prolonged use can lead to RSI Used to point and click on icons or menus Fast and accurate Need a flat surface to use them Most people are skilled at using a mouse, so no training is needed A tracker ball is User can get great Tracker ball basically an upside pointing accuracy, down ball mouse. without moving the hand The user runs their thumb over Useful where desk the ball to control space is limited the on-screen pointer For an optical mouse, the laser does not work well on all surfaces Some people find that the thumb gets painful with prolonged use Ball can get greasy and dirty

Manual Input Devices Device Uses Advantages Disadvantages Joystick Originally designed for pilots to control aeroplanes They give a more realistic gaming experience when playing games such as flight simulators Some people find them difficult to operate, especially in 3 -d environments Used to control wheelchairs and for playing games Scanner Used to convert printed images or text into a file of digital data There are two types: handheld and flatbed Many different types available Even cheap scanners produce quality images Pictures can use a lot of memory Images can be edited before use Issues of copyright protection The quality of the Any printed image final image is can be inserted dependent on the into a document original image

Manual Input Devices Device Digital Camera Uses Used for taking still images which can be uploaded to a computer for permanent storage A pointing device, Touchpad built into a laptop for convenience or Fingerpad Advantages Disadvantages You can preview the image before pressing the shutter button When the drive is full, images need to be uploaded to a computer or deleted No film needed or development costs High resolution camera does not Unwanted images guarantee good can be deleted images Portable - built into the laptop Takes practice to master Don’t need to Some people find carry extra them very fiddly equipment around Fingers need to be Small movements clean and free of grease needed to move the cursor

Automatic 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 Barcode reader Webcam

Automatic Input Devices Device Uses Banks print important data on the bottom of cheques using magnetic ink MICR Magnetic Ink Character Recognition This ink is then read by a computer Advantages Very quick and accurate processing of data – very low error rate. Humans could not achieve the same accuracy Disadvantages Expensive to produce and print magnetic ink, and the reader is also expensive Banks are the main user – very Very secure as any few other attempt to change applications the numbers on a cheque will be ignored as the reader only recognises magnetic ink in the same font

Automatic Input Devices Device OMR Optical Mark Recognition OCR Optical Character Recognition Uses Used when you mark the numbers with a pencil on a lottery ticket Advantages Disadvantages Very fast method of reading data, which reduces queuing time for lottery tickets Sometimes incomplete marks are not read correctly Also used to mark multiple choice exam. More accurate papers, and paper- than human based school data entry registers Only pre-prepared forms can be scanned into the computer Uses a scanner to scan text, then software converts the text into a word processor file Quicker than typing in the text Sometimes it is not very accurate Latest software can recognise tables and even handwriting Documents need to be proof-read after scanning Used to read post codes, as part of the sorting process Reduces the cost of posting a letter Only worth doing for large amounts of text

Automatic Input Devices Device Barcode Readers Used to identify products in shops Advantages Very quick and accurate way to enter data – suits The code is read by busy shops a barcode scanner which identifies the Prices changes are product name, made on the manufacturer and database, not the country of origin barcode – more flexible system Magnetic Found on the back of bank cards and Stripe Reader store loyalty cards Disadvantages All barcodes need to be programmed into the computer in advance The reader may not be able to read the barcode on wrinkled packaging Simple, cheap and Magnetic stripe effective can get scratched Not much data can The data on the be stored The stripe holds card can be Thieves can read information, such altered if needed data on cards then as the account ‘Chip n’ Pin’ has use the cards number and the PIN increased security themselves

Automatic Input Devices Device Uses Used to input sound into the Microphone computer Used to give the computer commands, or to dictate letters directly to a word processor Webcam Used to input moving images into the computer for use in online communication Advantages Very cheap piece of equipment Helpful for people with additional needs or for busy people who need very quick letters Very cheap piece of equipment Enables people to see each other whilst they chat Disadvantages Computer can misread voice instructions due to natural variations in people’s voices Generally, the sound quality from a PC microphone is poor The image quality from most webcams is poor The moving picture tends to flicker due to current limitations in data transfer

Output Devices

Output 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… ü Sound (speakers or headphones) ü Images & Text (screen or printer) ü Movement (actuator, electric motor)

Output Devices Monitor Speakers Printer Headphones Plotter

Output Devices Device Uses Thin Film Transistor TFT Monitor monitors are more commonly known as flat screens or LCD screens Advantages Take up very little Easy to damage space Colour contrast on Run very quietly cheaper models is and produce little not as good as heat CRT monitors Use about a third of the energy of a CRT monitor CRT Monitor Cathode Ray Tube is very old technology. Almost completely replaced by flat screen monitors Disadvantages You may get ‘dead’ pixels Robust and Large, bulky and difficult to damage unsightly Reliable Can be heavy Last for a very long time Produce a lot of heat Old technology

Output Devices Device Uses When connected to a computer through a sound card, music can be played Advantages Disadvantages Speakers are not useful in a network room, as everyone would disturb each A presentation can Speakers other be more powerful & with sound Headphones can be Headphones Gives feedback to user during general Games are a lot uncomfortable with computer use extended use more involving Plotter Can help blind people use the computer and realistic with sound These are specialist Very high quality printers that can printouts produce high Almost any size quality printouts paper can be used on large pieces of paper Slower than normal printers Expensive to purchase and run

Printers There are 3 main types of printer… Device Uses Advantages Disadvantages Inkjet General purpose Cheap to buy Ink cartridges can be use for family or very expensive Latest models home office can be very fast Print quality not always very good Laser Business use for Quality printing letters, Good for large stationery and areas of colour images Quiet & Quick More expensive to buy than inkjets Business use for duplicate documents Noisy and rather oldfashioned technology Dot Matrix Can make a carbon copy Can print on continuous rolls of paper Toner cartridges are expensive Poor quality and only prints in black ink

Input & Output Devices Drag the input and output devices to the correct side. . .

Keyword Activity Drag the missing words to the correct place in the sentences…

Input Device Wordsearch

Output Device Wordsearch

Input Device Crossword

Output Device Crossword

Quiz

Objectives After viewing this presentation, you should… § Know that an input device allows you to input data into a computer system. § Know that an output device allows you to view or use information from a computer system. § Be able to describe the advantages and disadvantages of a wide range of input and output devices. § Know the difference between a manual input device and an automatic input device. § Understand when to use different input and output devices.

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