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2-input-output-devices.ppt
- 1. Input & OutputDevices
- 2. An inputdevice 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 Devices There are two types of input device: manual and automatic.
- 3. Manual Input Devices A manual input device requires a human hand to control it… Mouse Keyboard Scanner Camera
- 4. Manual Input Devices Trackerball Joystick Graphics tablet A manual input device requires a human hand to control it…
- 5. Manual Input Devices Keyboard Themost 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 Disadvantages Device
- 6. Manual Input Devices Concept Keyboard Simplifiedkeyboard 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 makes the keyboard waterproof, so safer for food restaurants 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 Uses Advantages Disadvantages Device
- 7. Manual Input Devices Graphics Tablet Agraphics tablet consists of a pad and a special pen It allows artists and graphic designers to draw naturally as though they were drawing on 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 Disadvantages Device
- 8. Manual Input Devices Mouse Mostcommon 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 well on 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 Disadvantages Device
- 9. Manual Input Devices UsesAdvantages Disadvantages Device 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 for pilots 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
- 10. Manual Input Devices Digital Camera Usedfor 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 deleted High resolution camera does not guarantee good images Touchpad or 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 Disadvantages Device
- 11. 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 Webcam Barcode reader
- 12. Automatic Input Devices MICR Magnetic Ink Character Recognition Banksprint 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 Disadvantages Device
- 13. Automatic Input Devices OMR Optical Mark Recognition Usedwhen you mark the numbers with a pencil on a 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 human data entry Sometimes incomplete marks are not read correctly Only pre-prepared forms can be scanned into the computer Uses Advantages Disadvantages Device OCR Optical Character Recognition 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
- 14. Automatic Input Devices Barcode Readers Usedto 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 may not be able to read the barcode on wrinkled packaging Uses Advantages Disadvantages Device Magnetic Stripe Reader Found on the back of bank cards and store loyalty cards The stripe holds information, such as 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 stored Thieves can read data on cards then use the cards themselves
- 15. Uses Advantages Disadvantages Device Microphone Usedto 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 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
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- 17. Output Devices Anoutput 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)
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- 19. Output Devices TFT Monitor Thin FilmTransistor 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 of a CRT monitor Easy to damage Colour contrast on cheaper models is not as good as CRT monitors You may get ‘dead’ pixels Uses Advantages Disadvantages Device 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
- 20. Output Devices Speakers & Headphones When connectedto 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 realistic with sound Speakers are not useful in a network room, as everyone would disturb each other Headphones can be uncomfortable with extended use Uses Advantages Disadvantages Device Plotter These are specialist printers that can produce high quality printouts on large pieces of paper Very high quality printouts Almost any size paper can be used Slower than normal printers Expensive to purchase and run
- 21. Printers There are 3main types of printer… Dot Matrix Laser Inkjet Uses Advantages Disadvantages Device General purpose use for family or home office Cheap to buy Latest models can 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 use for duplicate documents Can make a carbon copy Can print on continuous rolls of paper Noisy and rather old- fashioned technology Poor quality and only prints in black ink
- 22. Drag the inputand output devices to the correct side... Input & Output Devices
- 23. Keyword Activity Drag themissing words to the correct place in the sentences…
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- 29. After viewing thispresentation, 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 and disadvantages of a wide range of input and output devices. Objectives Know the difference between a manual input device and an automatic input device.
- 30. End of Show Allimages are for viewing purposes only. Copyright 2008 © Smart Presentations Ltd. and its licensors. All rights reserved.