Mouse

The mouse was invented by Douglas Engelbart of Stanford Research Institute in 1963, after extensive usability testing. Engelbart's team called it "bug". It was one of several experimental pointing devices developed for Engelbart's oN-Line System (NLS). The other devices were designed to exploit other body movements—for example, head-mounted devices attached to the chin or nose—but ultimately the mouse won out because of its simplicity and convenience.
The first, bulky, mouse (pictured) used two gear wheels perpendicular to each other: the rotation of each wheel was translated into motion along one axis. Engelbart received patent US3541541 on November 17, 1970 for an "X-Y Position Indicator for a Display System". At the time, Engelbart intended that users would hold the mouse continuously in one hand and type on a five-key chord keyset with the other.

Mechanical mice

The so-called "ball mouse" was later invented in the early 1970s by Bill English while he was working for Xerox PARC; it replaced the external wheels with a single ball (that could rotate in any direction). The ball's motion, in turn, was detected using perpendicular wheels housed inside the mouse's body. This variant of the mouse resembled an inverted trackball and was the predominant form used with personal 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 as needed.
Modern computer mice took form at the École polytechnique fédérale de Lausanne (EPFL) under the inspiration of Professor Jean-Daniel Nicoud and the hands of engineer and watchmaker André Guignard. A spin-off of EPFL, Logitech, launched the first popular mice. The major movement translation techniques are by optical, mechanical and inertial sensors.

Optical mice

An optical mouse uses a light-emitting diode and photodiodes to detect the movement of the underlying surface, rather than moving some of its parts as in a mechanical mouse.
Early optical mice, circa 1980, were of two types. Some, such as those invented by Steve Kirsch of Mouse Systems Corporation, used an infrared LED and a four-quadrant infrared sensor to detect grid lines printed on a special metallic surface with infrared absorbing ink. Predictive algorithms in the CPU of the mouse calculated the speed and direction over the grid. Others, invented by Richard F. Lyon and sold by Xerox, used a 16-pixel visible-light image sensor with integrated motion detection on the same chip () and tracked the motion of light dots in a dark field of a printed paper or similar mouse pad (). These two mouse types had very different behaviors, as the Kirsch mouse used an x-y coordinate system embedded in the pad, and would not work correctly when rotated, while the Lyon mouse used the x-y coordinate system of the mouse body, as mechanical mice do. As computing power grew cheaper, it became possible to embed more powerful special-purpose image processing chips in the mouse. This advance enabled the mouse to detect relative motion on a wide variety of surfaces, translating the movement of the mouse into the movement of the pointer and eliminating the need for a special mouse pad. This advance paved the way for widespread adoption of optical mice.
Modern surface-independent optical mice work by using an optoelectronic sensor to take successive pictures of the surface on which the mouse is operating. Most of these mice use LEDs to illuminate the surface that is being tracked; LED optical mice are often mislabeled as "laser mice". Changes between one frame and the next are processed by the image processing part of the chip and translated into movement on the two axes using an optical flow algorithm. For example, the Agilent Technologies ADNS-2610 optical mouse sensor processes 1512 frames per second: each frame is a rectangular array of 18×18 pixels, and each pixel can sense 64 different levels of gray. Optomechanical mice detect movements of the ball optically, giving the precision of optical without the surface compatibility problems, whereas optical mice detect relative movement of the surface by examining the light reflected off it.

Laser mice

In 2004, Logitech, along with Agilent Technologies, introduced the laser mouse with its MX 1000 model. This mouse uses a small laser instead of a LED. The new technology can increase the resolution of the image taken by the mouse. The companies claim that this leads to a 20× increase in the sensitivity to the surface features used for navigation compared to conventional optical mice (see interference). Gamers have complained that the MX 1000 does not respond immediately to movement after it is picked up, moved, and then put down on the mouse pad. Newer revisions of the mouse do not seem to suffer from this problem, which is a power-saving feature (almost all optical mice, laser or LED based, also implement this power-saving feature, except those intended for use in gaming, where a millisecond of delay is significant). Since it is a wireless mouse, the engineers designed it to save as much power as possible. In order to do this, the mouse blinks the laser when in standby mode (8 seconds after the last motion). This function also increases the laser life.
As early as 1998, Sun Microsystems provided a laser mouse with their Sun SPARC Station servers and workstations.

Optical versus mechanical mice

Optical mice supporters claim optical rendering works better than mechanical mice, requires no maintenance and lasts longer due to fewer moving parts. Optical mice do not normally require any maintenance other than removing debris that might collect under the light emitter, although cleaning a dirty mechanical mouse is fairly straightforward too.
Mechanical mice supporters point out that optical mice generally cannot track on glossy and transparent surfaces, including many commercial mouse pads, causing them to periodically "spin" uncontrollably during operation. Mice with less image processing power also have problems tracking extremely fast movement, though high-end mice can track at 1 m/s (40 inches per second) and faster. Power conservation is typically not an issue for cabled mice:
At the time of writing (2006), mechanical mice have lower average power demands than their optical conterparts. This is of no practical concern for cabled mice, but has an impact on battery-powered wireless models. A typical mechanical model requires 25 mA at +5 V (= 0.125 W), or less, whereas an optical model attains 100 mA at +5 V (= 0.5 W) for optical devices (for a 4?1 ratio). Since optical mice render movement based on an image the LED reflects, performance on multi-colored mousepads may be unreliable. However, they will outperform mechanical mice on uneven, slick, squishy, sticky or loose surfaces, and generally in mobile situations where mouse pads are not available.

Inertial Mice

Inertial mice detect movement through a gyroscope, for every axis supported. Usually cordless, they often have a switch to deactivate the movement circuitry between use, allowing the user freedom of movement without affecting the pointer position.

3D Mice

In the late 1990s, Kantek introduced the 3D RingMouse. This wireless mouse was worn on a ring around a finger, which enabled the thumb to access three buttons. The mouse was tracked in three dimensions by a base station. Despite a certain appeal, it was finally discontinued because it did not provide sufficient resolution.

Connectivity and communication protocols

To transmit their input typical cabled mice use a thin electrical cord terminating in a standard connector, such as RS-232C, PS/2, ADB or USB. Cordless mice instead transmit data via infrared radiation (see IrDA) or radio (including Bluetooth). The electrical interface and the format of the data transmitted by commonly available mice has in the past varied between different manufacturers.

PS/2 interface and protocol

With the introduction of the IBM PS/2 personal computer series in 1987, IBM introduced the homonyms PS/2 interface for mice and keyboards, which was rapidly adopted by other manufacturers. The most visible change was the use of a round 6-pin mini-DIN, in lieu of the former 5-pin connector. In default mode (called stream mode) a PS/2 mouse communicates motion, and the state of each button, by means of 3-byte packets.

Extensions: IntelliMouse and others

A Microsoft IntelliMouse relies on an extension of the PS/2 protocol: it initially operates in standard PS/2 format, for backwards compatibility. After the host sends a special command sequence, it switches to an extended format, where a fourth byte carries information about wheel movements. The IntelliMouse Explorer works analogously, with the difference that its 4-byte packets also allow for two additional buttons (for a total of five).
The Typhoon mouse uses 6-byte packets which may be seen as a sequence of two standard 3-byte packets, and can thus be handled by ordinary PS/2 drivers. Other extended format are use by mouse vendors, often without public documentation.

Apple Desktop Bus

In 1986 Apple first implemented the Apple Desktop Bus allowing up to 16 devices, including arbitrarily many mice, to be daisy-chained together. Featuring only a single data pin, the bus used a purely polled approach to computer/mouse communications and survived as the standard on mainstream models until 1998 when the iMac began a switch to USB. The PowerBook G4 retained the Apple Desktop Bus for communication with its built in keyboard and trackpad until early 2005.

Jagath Krishnakumar