class lecture on input & output devices(part1)

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class lecture on input & output devices(part1)

  1. 1. BAF Shaheen English Medium School(SEMS)
  2. 2. Std: Ѵ Section : Bluebell/Lavender Subject: Computer StudiesSubject Teacher: Shah Md. Shariful Islam Date: 28-12-11
  3. 3. Input devices ObjectivesAfter the completion of this topic we will learn Definition of input devices in the context of any computer based system. Detail about various kinds of input devices Uses of the input devices. Advantages and disadvantages.
  4. 4. Definition for input devicesInput devices are hardware devices that allow data to be input into a computer. For example keyboard, mice, barcode reader are known as input devices.
  5. 5. keyboards The most common input devices and are used to input text, numbers and instructions into the computer. Most used layout is “QWERTY”. Recently developed keyboard is “Ergonomic keyboard”. An ergonomic keyboard is a computer keyboard designed with ergonomic considerations to minimize muscle strain and a host of related problems. Typically such keyboards are constructed in a V shape, to allow right and left hands to type at a slight angle more natural to the human form.
  6. 6.  Designed to reduce health related problems like carpal tunnel syndrome or repetitive strain injury(RSI) associated with the standard keyboard.
  7. 7.  Uses Keyboards are used to input data into applications software(e.g. text into word processors, numbers into spreadsheets, etc). They are also used for typing in commands to the computer(e.g. Prnt Scrn, Ctrl+P to print out, etc.)• Advantages Keyboards enable fast entry of new text into a document. They are a well-tried technology and a well-known method of entry. Most people find them easy to use. It is easy to do verification checks as data is entered, as it appears on the screen simultaneously.
  8. 8.  Disadvantages Users with limited arm/wrist use can find keyboards hard to use. Entering data using a keyboard is slow when compared to direct data entry (e.g. optical mark recognition). Keyboards are fairly large devices that devices that use up valuable desk space.
  9. 9.  The concept keyboard It uses icons or phrases instead of standard letters. Often used in fast food restaurants, offices and shops, where a single key represents an item.• Advantages It enables fast data entry, as there is no need to type in whole commands. They are waterproof, which is useful in a restaurant environment. These keyboards are tamper proof and so are useful in certain applications, preventing people from keying information which could potentially corrupt the computer system.
  10. 10. Concept keyboard
  11. 11.  Numeric keypads A numeric keypad is used to enter numbers only(although some have a function key ot allow input of alphabetic characters).• Uses Numeric keypads are used in automatic teller machines(ATMs), where customers can key in their personal identification number(PIN), and amount of money etc. Telephones have numeric keypads to allow phone numbers, etc. to be keyed in.
  12. 12.  Electronic point of sale(EPOS) terminals have numeric keypads in case the barcode reader fails to read the barcode and the number has to be keyed in manually by the operator. Chip and PIN devices have numeric keypads for entry of PIN, amount of money etc. They are used to enable fast entry of numeric data into a spreadsheet.
  13. 13. Electronic point of sale(EPOS) terminals
  14. 14.  Advantages Numeric keypads are faster than standard keyboards for entry of numeric data. Since many are small devices(e.g. mobile phones) they are very easy to carry around.• Disadvantages They can be difficult to use, due to very small keys. It is difficult to use them for entering text. Sometimes the order of the numbers on the keypad isn’t intuitive.
  15. 15.  Mice A mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface.• Usually two kinds of mice are found on the basis of their working principles• Mechanical mice
  16. 16.  A ball is used underneath the mouse to detect movement, so by moving the mouse around the user can control the position of a pointer on the screen. Usually two buttons are there; left button is used to select and the right button is used bring up drop-down menus. Many mice also have scroll button which speeds up the process of moving through a document.
  17. 17.  Optical mice They make use of one or LED(light-emitting diode) and an imaging array of photodiodes to detect movement relative to the underlying surface.
  18. 18. • The cordless mouse doesn’t need any wire to connect with the computer.• Advantages It has no moving parts and it also doesn’t pick up any dirt. Since it has no ‘skidding’ problem like the older ones it improves performances.
  19. 19.  Uses Mice can be used for opening, closing, and minimizing software. They can be used for grouping, moving and deleting files. They are very useful when editing images. Mice are used for controlling the position of a pointer on the screen to allow selection from a menu or selecting an icon and for scrolling up and down/left to right.
  20. 20.  Advantages It can be faster to select an option using a mouse rather than a keyboard. Mice enable rapid navigation through applications and the internet. Mice are small and so take up little area.• Disadvantages People with restricted hand/wrist movement can find it hard to operate a mouse. Mice are easily damaged and older type of mouse also quickly becomes clogged up with dirt. They are difficult to use if there is no flat surface readily available.
  21. 21.  Touchpads Touchpads are used in many laptop computers as a pointing device. The pointer is controlled by the user moving their finger on the touchpad and then gently tapping it to simulate the left hand button of a mouse. They also have buttons under the touchpad which serve the same function as the left and right buttons on a mouse.
  22. 22.  Advantages It can be faster to select an option using a touchpad rather than a keyboard. Touchpads enable rapid navigation through applications and the internet. Since the touchpad is integrated into the laptop compute, there is no need for a separate mouse, aiding portability. They can be used even when there are no flat surfaces available.• Disadvantages It can be more difficult to control the pointer when compared with a mouse. They are more difficult to use when doing certain operations such as “drag and drop”.

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