- Both identical pointing device

Mouse

  • Simple than keyboard (Simple click)
  • Position of graphical cursor controlled by h/w & s/w
  • Driver s/w generates & tracks cursor position
  • Pressing mouse button – selection of options given by appln prog
  • 2 / 3 button – function defined by s/w
  • Transmits signal interpreted by mouse driver
  • Action taken by system depends on OS & appln prog
  • Gestures: single click, double click & drag

Types

  • Mechanical mouse
  • Opto-mechanical mouse
  • Optical mouse

Mechanical mouse

  • Small round rubber ball touches mouse pad – rotates on mouse move

  • Two flywheels inside touching ball senses horizontal & vertical movements

  • Also connected to resistive element forming mesh of fine black cross hairs on mouse moves, The ball translates movements into electrical signals. 
  • Simple & cheaper & Needs routine maintenance

Opto- mechanical mouse

  • Ball & light sensitive semiconductors generate signals
  • No wire mesh
  • 2 right angled rollers with slotted perforated wheels
  • One side of hole – Led & other side photodiode/transistor for photosensor
  • On mouse move, ball rotates & rollers rotate slotted wheels.
  • Light is alternatively blocked & allowed 
  • Photosensor generates series of pulses
  • longer life & better reliability
  • Periodic cleaning to remove dust & dirt

Optical mouse

  • No ball or rollers
  • Special mouse pad with grid
  • Mouse movement tracked by LEDs & light sensitive transistors
  • Expensive
  • Better accuracy & high reliability
  • No moving parts & no maintenance

Trackball

  • Mouse turned upside down
  • Ball present on top & moved with fingertips
  • Bigger than mouse ball 
  • Better resolution
  • Less space 
  • Convenient in car / aeroplane where notebook PC/laptop is used
  • Some keyboards have built-in trackball