In computing, a mouse is a pointing device that functions by detecting two-dimensionalmotion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons.

The mouse sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features that can add more control or dimensional input. The mouse's motion typically translates into the motion of a pointer on a display, which allows for fine control of a graphical user interface.

Mechanical mice

Operating an opto-mechanical mouse. moving the mouse turns the ball. X and Y rollers grip the ball and transfer movement Optical encoding disks include light holes. Infrared LEDs shine through the disks. Sensors gather light pulses to convert to X and Y vectors.

German company Telefunken published on their early ball mouse, called "Rollkugel" (German for "rolling ball"), on October 2, 1968.^[13] Telefunken's mouse was then sold commercially as optional equipment for their TR-440 computer, which was first marketed in 1968. Telefunken did not apply for a patent on their device. Bill English, builder of Engelbart's original mouse,^[14] created a ball mouse in 1972 while working for Xerox PARC.^[15]

The ball mouse replaced the external wheels with a single ball that could rotate in any direction. It came as part of the hardware package of the Xerox Alto computer. Perpendicular chopper wheels housed inside the mouse's body chopped beams of light on the way to light sensors, thus detecting in their turn the motion of the ball. This variant of the mouse resembled an inverted trackball and became the predominant form used withpersonal computers throughout the 1980s and 1990s. The Xerox PARC group also settled on the modern technique of using both hands to type on a full-size keyboard and grabbing the mouse when required.

Mechanical mouse, shown with the top cover removed. The scroll wheel is grey, to the right of the ball.

The ball mouse has two freely rotating rollers. They are located 90 degrees apart. One roller detects the forward–backward motion of the mouse and other the left–right motion. Opposite the two rollers is a third one (white, in the photo, at 45 degrees) that is spring-loaded to push the ball against the other two rollers. Each roller is on the same shaft as an encoder wheel that has slotted edges; the slots interrupt infrared light beams to generate electrical pulses that represent wheel movement. Each wheel's disc, however, has a pair of light beams, located so that a given beam becomes interrupted, or again starts to pass light freely, when the other beam of the pair is about halfway between changes.

Simple logic circuits interpret the relative timing to indica