Input Device Facts

Common input devices include:

  • Keyboard
  • Mouse
  • Trackball
  • Drawing tablet
  • Touchscreen
  • Bar code reader

Common interfaces used for connecting input devices include:

  • 5-pin DIN for keyboards on XT and AT motherboards. A keyboard with a 5-pin DIN connector is sometimes called an AT keyboard, because it attaches to a computer with an AT motherboard.
  • DB-9 (serial) connector for mouse and older keyboards (rarely used today).
  • 6-pin mini-DIN (PS/2 connector) for keyboard and mouse.
  • USB for keyboard, mouse, and other devices.
  • Infrared and wireless connections for keyboards, mouse, and other devices.

The following table lists several considerations for selecting input devices.

Device Type / Considerations
Keyboard /
  • Many keyboards include special function keys that simplify playing music or browsing the Web.
  • Some keyboards include a built-in USB port that can be used to connect other peripheral devices.

Mouse /
  • Mechanical mice use a roller ball to detect motion. The roller ball must be cleaned periodically to ensure proper functionality.
  • Optical mice use light rays to detect motion. Optical mice require less maintenance than mechanical mice.
  • Motion-based mice can accurately detect mouse movement while in the air. This particular device can attach to a user's head and moves the cursor when the head moves.
  • You can select mice with multiple additional buttons or a scroll wheel to add functionality.

Touch screen / There are three basic types of touch screens.
  • A capacitive screen uses a thin electrically charged layer placed over the monitor screen. When touched, the charge moves from the capacitive surface to the touching object. The screen location of the touch is calculated and sent to the computer. This method blocks some of the light emanating from the monitor.
  • A resistive screen uses a glass panel covered with two metallic layers (one conductive and the other resistive) separated by a very narrow gap and mounted over the monitor screen. A protective layer is applied to the touch surface. When the screen is touched, the two metallic layers make contact and that location is calculated. This type of touch screen also blocks some of the monitor's light emanation.
  • A surface acoustic wave screen places tiny matching transducers across the screen surface from each other (one to send and the other to receive). When an object touches the screen surface, the signal is interrupted and that location is then calculated. This type of touch screen does not visually impair the monitor.