The trackball, a related pointing device, was invented in 1941 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 NavyScientific 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 a ball tracker called "roller ball", for this purpose.[5][6] The device was patented in 1947,[6] 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.[5] Another early trackball was built by British electrical engineer Kenyon Taylor in collaboration with Tom Cranston and Fred Longstaff. Taylor was part of the original Ferranti Canada, working on the Royal Canadian Navy's DATAR (Digital Automated Tracking and Resolving) system in 1952.[7] DATAR was similar in concept to Benjamin's display. The trackball used four disks to pick up motion, two each for the X and Y directions. Several rollers provided mechanical support. When the ball was rolled, the pickup discs spun and contacts on their outer rim made periodic contact with wires, producing pulses of output with each movement of the ball. By counting the pulses, the physical movement of the ball could be determined. A digital computer calculated the tracks, and sent the resulting data to other ships in a task force using pulse-code modulation radio signals. This trackball used a standard Canadian five-pin bowling ball. It was not patented, as it was a secret military project as well.[8][9] Early mouse patents. From left to right: Opposing track wheels by Engelbart, Nov. 1970, U.S. Patent 3,541,541. Ball and wheel by Rider, Sept. 1974, U.S. Patent 3,835,464. Ball and two rollers with spring by Opocensky, Oct. 1976, U.S. Patent 3,987,685 Independently, Douglas Engelbart at the Stanford Research Institute (now SRI International) invented his first mouse prototype in the 1960s with the assistance of his lead engineer Bill English. [10] They christened the device the mouse as early models had a cord attached to the rear part of the device looking like a tail and generally resembling the common mouse.[11] Engelbart never received any royalties for it, as his employer SRI held the patent, which ran out before it became widely used in personal computers.[12] The invention of the mouse was just a small part of Engelbart's much larger project, aimed at augmenting human intellect via theAugmentation Research Center.[13][14] Inventor Douglas Engelbart holding the first computer mouse,[15] showing the wheels that make contact with the working surface. Several other experimental pointing-devices developed for Engelbart's oN-Line System (NLS) exploited different body movements – for example, head-mounted devices attached to the chin or nose – but ultimately the mouse won out because of its speed and convenience.[16] The first mouse, a bulky device (pictured) used two wheels perpendicular to each other: the rotation of each wheel translated into motion along one axis. At the time of the "Mother of All Demos", Englebart's group had been using their second generation, 3-button mouse for about a year. See the image of that mouse at Picture showing 2nd G mouse (A public domain version of this image would be nice.) On 2 October 1968, just a few months before Engelbart released his demo on 9 December 1968, a mouse device named Rollkugel (German for "rolling ball") was released that had been developed and published by the German company Telefunken. As the name suggests and unlike Engelbart's mouse, the Telefunken model already had a ball. It was based on an earlier trackball-like device (also namedRollkugel) that was embedded into radar flight control desks. This had been developed around 1965 by a team led by Rainer Mallebrein at Telefunken Konstanz for the German Bundesanstalt für Flugsicherung as part of their TR 86 process computer system with its SIG 100-86[17] vector graphics terminal. The first ball-based computer mouse in 1968, Telefunken RollkugelRKS 100-86 for their TR 86 process computer system. When the development for the Telefunken main frame TR 440 (de) began in 1965,Mallebrein and his team came up with the idea of "reversing" the existing Rollkugelinto a moveable mouse-like device, so that customers did not have to be bothered with mounting holes for the earlier trackball device. Together with light pens and trackballs, it was offered as optional input device for their system since 1968. Some samples, installed at the Leibniz-Rechenzentrum in Munich in 1972, are still well preserved.[18][19] Telefunken considered the invention too small to apply for a patent on their device. The Xerox Alto was one of the first computers designed for individual use in 1973, and is regarded as the grandfather of computers that utilize the mouse.[20] Inspired by PARC's Alto, the Lilith, a computer which had been developed by a team aroundNiklaus Wirth at ETH Zürich between 1978 and 1980, provided a mouse as well. The third marketed version of an integrated mouse shipped as a part of a computer and intended for personal computer navigation came with the Xerox 8010 Star Information System in 1981. By 1982 the Xerox 8010 was probably the best-known computer with a mouse, and the forthcoming Apple Lisa was rumored to use one, but the peripheral remained obscure; Jack Hawley of The Mouse House reported that one buyer for a large organization believed at first that his company sold lab mice. Hawley, who manufactured mice for Xerox, stated that "Practically, I have the market all to myself right now"; a Hawley mouse cost $415.[21] That year Microsoft made the decision to make the MS-DOS program Microsoft Word mouse-compatible, and developed the first PC-compatible mouse. Microsoft's mouse shipped in 1983, thus beginning Microsoft Hardware. [22] However, the mouse remained relatively obscure until the 1984 appearance of the Macintosh 128K, which included an updated version of the Lisa Mouse [23] and theAtari ST in 1985. Operation[edit] Further information: Point and click A mouse typically controls the motion of a pointer in two dimensions in a graphical user interface (GUI). The mouse turns movements of the hand backward and forward, left and right into equivalent electronic signals that in turn are used to move the pointer. The relative movements of the mouse on the surface are applied to the position of the pointer on the screen, which signals the point where actions of the user take place, so that the hand movements are replicated by the pointer.[24] Clicking or hovering (stopping movement while the cursor is within the bounds of an area) can select files, programs or actions from a list of names, or (in graphical interfaces) through small images called "icons" and other elements. For example, a text file might be represented by a picture of a paper notebook, and clicking while the cursor hovers this icon might cause a text editing program to open the file in a window. Different ways of operating the mouse cause specific things to happen in the GUI:[24] Click: pressing and releasing a button. (left) Single-click: clicking the main button. (left) Double-click: clicking the button two times in quick succession counts as a different gesture than two separate single clicks. (left) Triple-click: clicking the button three times in quick succession. Right-click: clicking the secondary button. Middle-click: clicking the tertiary button. Drag and drop: pressing and holding a button, then moving the mouse without releasing. (Using the command "drag with the right mouse button" instead of just "drag" when one instructs a user to drag an object while holding the right mouse button down instead of the more commonly used left mouse button.) Mouse button chording (a.k.a. Rocker navigation). Combination of right-click then left-click. Combination of left-click then right-click or keyboard letter. Combination of left or right-click and the mouse wheel. Clicking while holding down a modifier key. Moving the pointer a long distance: When a practical limit of mouse movement is reached, one lifts up the mouse, brings it to the opposite edge of the working area while it is held above the surface, and then replaces it down onto the working surface. This is often not necessary, because acceleration software detects fast movement, and moves the pointer significantly faster in proportion than for slow mouse motion. Multi-touch: this method is similar to a multi-touch trackpad on a laptop with support for tap input for multiple fingers, the most famous example being the Apple Magic Mouse. Mouse gestures[edit] Main article: Pointing device gesture Users can also employ mice gesturally; meaning that a stylized motion of the mouse cursor itself, called a "gesture", can issue a command or map to a specific action. For example, in a drawing program, moving the mouse in a rapid "x" motion over a shape might delete the shape. Gestural interfaces occur more rarely than plain pointing-and-clicking; and people often find them more difficult to use, because they require finer motor-control from the user. However, a few gestural conventions have become widespread, including the drag and drop gesture, in which: 1. The user presses the mouse button while the mouse cursor hovers over an interface object 2. The user moves the cursor to a different location while holding the button down 3.