INPUT DEVICES

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INPUT DEVICES

• Devices which are used for entering the data
  into the
  computer.
• The process of entering the data into the
  computer system.
• Transferring the data into the Machine readable
  form.
• Supply the data for further processing.

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Data Entry Concepts

• Entering of the data into the computer in timely
  manner, at reasonable cost and with minimum of
  errors.
• 2 basic ways in which data are entered
• Transcriptive Data Entry
• Source Data Entry
• In Transcriptive, the data is entered on
  documents. For example, handwritten.
• In Source Data Entry, the data are prepared at
  source in machine-readable form.

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ON-LINE/OFF-LINE

• Device used to enter the data can be either
  on-line or off-line.
• On-line refers to devices that are directly
  connected to CPU.
• Off-line refers to devices that are not directly
  connected.

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INPUT ACCURACY

• Errors may occur during entering the data.
• 2 various methods used to eliminate the errors
• Verification
• Validation
• Verification is the checking of data against a
  known source.
• Validation is the checking of data that deviate
  from this range.

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INPUT DEVICES

• Input is the process of entering and translating
  incoming data into Machine-readable form.
• Hardware is the physical component of computer
  system.
• Any hardware that is attached to main unit of
  computer is Peripheral Device.
• So input device is peripheral device through
  which data is entered.
• Various Input Devices are.

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1. KEYBOARD

• Most preferred and common input device.
• Traditional QWERTY keyboard.
• Feature of the Keyboard
• Standard Typewriter Keys
• Function Keys
• Special Purpose keys
• Cursor-movement keys
• Numeric keys

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2. MOUSE

• Developed by Doug Engelbart in 1960.
• It is used instead of Enter (Return) key on
  keyboard.
• Operates either electromechanically or
  optically.
• electromechanical mouse has sphere on its under
  side.
• Optical mouse travels over special table of grid
  lines.

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3. JOYSTICK

• Input device that enables the user to control
  the position of the cursor with the help of
  lever.
• It sends the digital signals to control the
  cursor movements.
• Used to play computer games.
• It provides the user eight direction movements.

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4. TRACKBALL

• Input device which is variation in the mouse.
• It is like an upside down mouse.
• It has ball on the top and the user moves the
  ball directly with the hands.
• Firstly used in the Laptops.
• Rotation of the sphere translates the direction
  and speed into digital signals used to control
  the cursor.

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5. TOUCHPAD

• Input device used in the modern laptops.
• User can move the cursor around the screen by
  moving the finger on the pad.
• For clicking there are two buttons and also the
  user can tap the pad for clicking an icon.

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6. TRACKPOINT

• Input button which is protruded in between the
  keys of the keyboard.
• Works like mouse.
• Rotate the cursor around the screen.

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7. TOUCH SCREEN

• It registers the input when a finger or object
  comes in contact with the screen.
• It employs the technique of infrared beams and
  Ultrasonic Acoustic Waves.
• Infrared beams crisscross the surface of the
  screen and when beam is broken the location is
  recorded.
• Ultrasonic waves pass over the surface of the
  screen and when wave signal is interrupted the
  location is recorded.

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8. LIGHT PEN

• Hand held pen shaped input device connected by
  cable to computer and is used special software to
  detect light.
• It looks like an ordinary pen but its tip is
  light sensitive detector.
• It does not emit light rather it reacts to light
  through photosensitive detector.
• Frequently used by the graphic designers and
  drafting engineers.

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9. Digitizer

• Input device similar to light pen.
• Difference is it uses separate pad called
  graphic tablet on which the pointing device is
  moved.

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10. SCANNER

• Also called Optical Reader.
• works like photocopier machine.
• It digitizes the information into computer.
• It take an electronic image of the text or
  graphs and breaks each image into thousands of
  light dark dots.
• Passes strong light on the text.

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11. MICR

• Magnetic-ink Character Recognition.
• The interpretation by computer of line of
  characters written in special magnetic ink.
• Mainly used in the banks for the processing of
  cheques.

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12. OMR

• Optical-Mark Recognition.
• Simplest form of optical recognition.
• Employs mark sensing.
• High intensity of light that is directed in the
  form of beam at the sheets of the paper being fed
  through it.
• To scan and translate the locations of pen or
  pencil marks into computer.

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13. BCR (OBR)

• Bar Coded Recognition (Optical Bar Recognition).
• Optical bar reader scans, recognizes and
  interprets a patterns of lines that form a bar
  code.
• Bar code also called product codes.
• By passing some laser beams.
• UPC (Universal Product Code)

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14. OCR

• Optical Character Recognition.
• Device that reads alphanumeric characters of
  both handwritten or typed text.
• These characters are interpreted by passing some
  strong light.
• The characters must be recognized by
  standardized fonts called Optical fonts.