Ball mouse

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.

A computer mouse is a pointing device (hand control) that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, which allows a smooth control of the graphical user interface.

Physically, a mouse consists of an object held in one's hand, with one or more buttons. Mice often also feature other elements, such as touch surfaces and "wheels", which enable additional control and dimensional input.

The earliest known publication of the term mouse as referring to a computer pointing device is in Bill English's July 1965 publication, "Computer-Aided Display Control".

The plural for the small rodent is always "mice" in modern usage. The plural of a computer mouse is "mouses" and "mice" according to most dictionaries, but "mice" being more common. The first recorded plural usage is "mice"; the online Oxford Dictionaries cites a 1984 use, and earlier uses include J. C. R. Licklider's "The Computer as a Communication Device" of 1968.

The trackball, a related pointing device, was invented in 1946 by Ralph Benjamin as part of a World War II-era fire-control radar plotting system called Comprehensive Display System (CDS). Benjamin was then working for the British Royal Navy Scientific Service. Benjamin's project used analog computers to calculate the future position of target aircraft based on several initial input points provided by a user with a joystick. Benjamin felt that a more elegant input device was needed and invented what they called a "roller ball" for this purpose.

The device was patented in 1947, but only a prototype using a metal ball rolling on two rubber-coated wheels was ever built, and the device was kept as a military secret.