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Saturday, May 7, 2011

Input Device of Computer


What is peripheral?
v  Devices that connects to a system unit and is controlled by the Central Processing Unit (CPU) in the computer

         What is input ?
          Any data or instructions entered into memory of computer

What are the two types of input?
v  Data
Ø  Unprocessed text, numbers, images, audio and video
v  Instructions
Ø  Programs
Ø  Commands
Ø  User responses

         What are input devices ?
          Input devices is any hardware component that allows an user to enter data or instructions into a computer

The categories of input devices:
          The keyboard
          Pointing devices
          Scanners and Reading devices
          Input devices for the physically challenged users

         What is a keyboard?
          An input device that contains keys, users press to enter data into a computer system.keyboard Converts letters, numbers and other characters into electronic signals that are machine-readable.
                       It is a 8-bit code (ASCII-8) or able to accommodate 256 different
                     Characters.
          Desktop computer typically have from 101 to 105 keys
         Required by software with Command Line Interface (CLI)

         How is the keyboard divided?
          Typing area
          Numeric keypad
          Function keys, special keys that issue command

  •            The types of keyboards:
v  QWERTY
v  DVORAK
v  Enhanced keyboard
v  Wireless keyboard
v  Portable keyboard
v  Laptop keyboard
v  Handheld keyboard
v  Ergonomic keyboard
v  Virtual keyboard

v  QWERTY keyboard
v  The most widely used type of keyboard, so named because the first letters on the top alphabetic line spell QWERTY

v  DVORAK keyboard
v  A type of keyboard that places frequently types letters in the middle of the typing area

          Enhanced keyboard
v  A keyboard that has 12 function keys along the top : 2 Control (CTRL) keys and 2 Alternate (ALT) keys along the bottom and a set of arrow keys and other additional keys between the typing area and the numeric keypad

       Wireless or Cordless keyboard
v  Battery-powered keyboard that transmits data using wireless technology, such as radio waves or infrared light waves
         Portable keyboard
          A full sized keyboard, that an end-user conveniently can attach or remove from a handheld computer or PDA

         Laptop and Handheld keyboard
          Notebook and many handheld computers have built-in keyboards

  •           Ergonomics keyboard
v  Design to minimise strain on hands or wrists
v  Ergonomics incorporates comfort, efficiency and safety into design of items of workplace
         Virtual keyboard.
        Projects infrared image of keyboard onto any flat surface

         What is a pointing device?

v  An input device that allows the user to control a pointer on the display screen
v  Required by software with Graphical User Interface (GUI)

         The types of pointing devices
          Mouse
          Trackball
          Touchpad
          Pointing stick
          Joystick and Wheel
          Light pen
          Touch screen
          Stylus or Digital pen

         What is a Mouse ?
          Pointing device that fits under palm of hand
          Pointing device controls movement of pointer, also called mouse pointer
          A pointer on screen takes several shapes
 The types of pointing devices :
          Mechanical mouse
          Optical mouse   
          Cordless mouse


          How does a mechanical mouse work ?
          Rubber or metal ball is on its underside
          Movement of mouse translates into signals that computer understand

         How does an optical mouse work ?
          Senses light to detect mouse’s movement
          More precise than mechanical mouse
          Connect using a cable or wireless

         Wireless or Cordless mouse

         What is a trackball ?
          Stationary pointing device with a ball on its top
          To move pointer, rotate ball with thumb, fingers or palm of hand.


What is a Touch pad?
          Touch pad is small, flat, rectangular pointing device that is sensitive to pressure and motion. It Often used in laptop computers.

          What is a pointing stick?
          Pointing stick is pointing device shaped like pencil eraser positioned between keys on keyboard
          Moves pointer as pressure is applied
          Often used in laptop computers

         What are a joystick and a wheel?
          Joystick
          Is vertical lever mounted on a base
          It enables the user to move within the screen’s environment
          Widely used in computer games industry
          Wheel
          Wheel is steering-wheel-type input device
          Users turn the wheel to simulate driving a car, truck etc.
          Most wheels also include foot pedals to simulate car brakes and accelerator

          What is a light pen?
                     Handheld input device that can detect light
          Press light pen against screen surface and then press button on pen

         What is a Touch screen ?
          Monitor has a touch-sensitive panel
          Touch areas of screen with finger
          Used to issue simple commands or choose from a list of options
          Often used with kiosk

          What is a stylus or digital pen ?
          Looks like a ballpoint pen, but uses pressure to write text and draw lines
          Used with graphics tablets, flat electronic boards and handheld computers
 

          What is an Electronic signature ?
          Is a legal signature created using special software, stylus and graphics tablet
          Also called as e-signature

    What is a scanner ?
          Light-sensing device that captures data directly from source document
          Source document is original form of data (printed text or graphics)
          Used for image processing, converting paper documents into electronic images




          What is an optical reader?
          Device that uses light source to read characters, marks and codes and then converts them into digital data

          What is an OCR font?
          OCR device determines characters’ shapes by detecting patterns of light and dark
          OCR software converts shapes into characters the computer can understand

         What is a turnaround document?
          It is a document that after being output by the computer can be used to record data and this data can then be input to the computer using a document reader
          Portion you return has information printed in OCR characters

          What is an Optical Mark Recognition (OMR) ?
          Reads hand-drawn pencil marks such as small circles or rectangles
          Used for ballots, enrollment application, attendance, questionnaires, course evaluation and multiple choice tests and examination

          What is a Bar code?
          Identification code that consists of a set of vertical lines and spaces of different widths
          The symbol of the Universal Product Code (UPC)
  •           What is a Bar code scanner?

v  Uses laser beam to read bar codes

  • What is a Magnetic-Ink Character Recognition (MICR) reader?

v  Can read text printed with magnetized ink
v  Banking industry almost exclusively uses MICR for cheque processing

          What is Biometrics?
          Authenticates person’s identity by verifying personal characteristic
          Fingerprint scanner captures curves and indentations of fingerprint
          Hand geometry system measures shape and size of person’s hand

          What are examples of Biometric technology?
          Voice verification system compares live speech with stored voice pattern
          Signature verification system recognizes shape of signature
          Iris recognition system reads patterns in blood vessels in back of eye
          Biometric data is sometimes stored on smart card, which stores personal data on 
            microprocessor embedded in card.

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