Monday, November 10, 2008


A contemporary computer mouse, with the most common standard features: two buttons and a scroll wheel.

In computing, a mouse (plural mice, mouse devices, or mouses) is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of a small jude, held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features 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.

The name mouse, originated at the Stanford Research Institute, derives from the resemblance of early models (which had a cord attached to the rear part of the device, suggesting the idea of a tail) to the common mouse.[1].

The first marketed 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.



[edit] Etymology and plural

The first known publication of the term "mouse" as a pointing device is in Bill English's 1965 publication "Computer-Aided Display Control".[2]

The Compact Oxford English Dictionary (third edition) and the fourth edition of The American Heritage Dictionary of the English Language endorse both computer mice and computer mouses as correct plural forms for computer mouse. Some authors of technical documents may prefer either mouse devices or the more generic pointing devices. The plural mouses treats mouse as a "headless noun."

Two manuals of style in the computer industry – Sun Technical Publication's Read Me First: A Style Guide for the Computer Industry and Microsoft Manual of Style for Technical Publications from Microsoft Press – recommend that technical writers use the term mouse devices instead of the alternatives.

[edit] Technologies

[edit] Early mice

Douglas Engelbart at the Stanford Research Institute invented the mouse in 1963[3][4] after extensive usability testing. He never received any royalties for it, as his patent ran out before it became widely used in personal computers.[5]

Eleven years earlier, the Royal Canadian Navy had invented the trackball using a Canadian five-pin bowling ball as a user interface for their DATAR system.[6]

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 simplicity and convenience. The first mouse, a bulky device (pictured) used two gear-wheels perpendicular to each other: the rotation of each wheel translated into motion along one axis. Engelbart received patent US3541541 on November 17, 1970 for an "X-Y Position Indicator for a Display System".[7] At the time, Engelbart envisaged that users would hold the mouse continuously in one hand and type on a five-key chord keyset with the other.[8] The concept was preceded in the 19th century by the telautograph, which also anticipated the fax machine.

[edit] Mechanical mice

Mechanical mouse shown with the top cover removed.
Operating a mechanical mouse.
1: moving the mouse turns the ball.
2: X and Y rollers grip the ball and transfer movement.
3: Optical encoding disks include light holes.
4: Infrared LEDs shine through the disks.
5: Sensors gather light pulses to convert to X and Y velocities.

Bill English, builder of Engelbart's original mouse,[9] invented the so-called ball mouse in 1972 while working for Xerox PARC.[10] 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 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 when required.

The ball mouse utilizes two rollers rolling against two sides of the ball. One roller detects the horizontal motion of the mouse and other the vertical motion. The motion of these two rollers causes two disc-like encoder wheels to rotate, interrupting optical beams to generate electrical signals. The mouse sends these signals to the computer system by means of connecting wires. The driver software in the system converts the signals into motion of the mouse pointer along X and Y axes on the screen.

Ball mice and wheel mice were manufactured for Xerox by Jack Hawley, doing business as The Mouse House in Berkeley, California, starting in 1975.[11][12]

Based on another invention by Jack Hawley, proprietor of the Mouse House, Honeywell produced another type of mechanical mouse.[13][14] Instead of a ball, it had two wheels rotating at off axes. Keytronic later produced a similar product.[15]

Modern computer mice took form at the École polytechnique fédérale de Lausanne (EPFL) under the inspiration of Professor Jean-Daniel Nicoud and at the hands of engineer and watchmaker André Guignard.[16] This new design incorporated a single hard rubber mouseball and three buttons, and remained a common design until the mainstream adoption of the scroll-wheel mouse during the 1990s.[17]

Another type of mechanical mouse, the "analog mouse" (now generally regarded as obsolete), uses potentiometers rather than encoder wheels, and is typically designed to be plug-compatible with an analog joystick. The "Color Mouse," originally marketed by Radio Shack for their Color Computer (but also usable on MS-DOS machines equipped with analog joystick ports, provided the software accepted joystick input) was the best-known example.

[edit] Mechanical or opto-mechanical

A mouse described as simply "mechanical" has a contact-based incremental rotary encoder,[citation needed] a system prone to drag and unreliability of contact. Opto-mechanical mice still use a ball or crossed wheels, but detect shaft rotation using an optical encoder with lower friction and more certain performance.

[edit] Optical mice

An optical mouse uses a light-emitting diode and photodiodes to detect movement relative to the underlying surface, rather than moving some of its parts — as in a mechanical mouse.

[edit] Early optical mice

Early optical mice, circa 1980, came in two different varieties:[18]

  1. Some, such as those invented by Steve Kirsch[19][20] of Mouse Systems Corporation, used an infrared LED and a four-quadrant infrared sensor to detect grid lines printed with infrared absorbing ink on a special metallic surface. Predictive algorithms in the CPU of the mouse calculated the speed and direction over the grid.
  2. 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[21] and tracked the motion of light dots in a dark field of a printed paper or similar mouse pad.[22]

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 the pad was rotated, while the Lyon mouse used the x-y coordinate system of the mouse body, as mechanical mice do.

The optical sensor from a Microsoft Wireless IntelliMouse Explorer (v. 1.0A).

[edit] Modern optical mice

Modern surface-independent optical mice work by using an optoelectronic sensor to take successive pictures of the surface on which the mouse operates. As computing power grew cheaper, it became possible to embed more powerful special-purpose image-processing chips in the mouse itself. 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. Optical mice illuminate the surface that they track over, using an LED or a laser diode. 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 estimation algorithm. For example, the Avago Technologies ADNS-2610 optical mouse sensor processes 1512 frames per second: each frame consisting of a rectangular array of 18×18 pixels, and each pixel can sense 64 different levels of gray.[23]

[edit] Infrared Optical mice

Some newer optical mice including some from logitech's lx series use an infrared sensor instead of a light emitting diode. This saves power and can be more accurate.

[edit] Laser mice

The laser mouse uses an infrared laser diode instead of an LED to illuminate the surface beneath their sensor. As early as 1998, Sun Microsystems provided a laser mouse with their Sun SPARCstation servers and workstations.[24] However, laser mice did not enter the mainstream market until 2004, when Logitech, in partnership with Agilent Technologies, introduced its MX 1000 laser mouse.[25] This mouse uses a small infrared laser instead of an LED and has significantly increased the resolution of the image taken by the mouse. The laser enables around 20 times more surface tracking power to the surface features used for navigation compared to conventional optical mice, via interference effects. While the implementation of a laser slightly increases sensitivity and resolution, the main advantage comes from power usage.[26]

[edit] Color of optical mouse diodes
Example of a Logitech optical mouse with a blue diode.

The color of the optical mouse's light-emitting diodes varies with each model. Red was (and still is today) the most common, as red diodes were the cheapest when optical mice first arrived on the market. Today, a wide array of colors exist, such as blue or green. Some models' diodes even change color, cycling through colors of the rainbow for instance.

[edit] Power-saving in optical mice

Manufacturers often engineer their optical mice — especially battery-powered wireless models — to save power when possible. In order to do this, the mouse dims or blinks the laser or LED when in standby-mode (Each mouse has a different standby time). This function may also increase the laser / LED life. Mice designed specifically for gamers, such as the Logitech G5 or the Razer Copperhead, often lack this feature in an attempt to reduce latency and to improve responsiveness.

A typical implementation in Logitech mice (eg. Cordless Mouseman optical) has four power states, where the sensor is pulsed at different rates per second:

  • 1500 - full on condition for accurate response while moving, illumination appears bright.
  • 100 - fallback active condition while not moving, illumination appears dull.
  • 10 - Standby
  • 2 - Sleep state

Some other mice turn the sensor fully off in the sleep state, requiring a button click to wake.

Some mice such as some mice in logitech's lx series use an infared sensor to save power (as stated above)

[edit] Optical versus mechanical mice
The Logitech iFeel optical mouse uses a red LED to project light onto the tracking surface.

Unlike mechanical mice, which can become clogged with lint, optical mice have no rolling parts; therefore, they do not require maintenance other than removing debris that might collect under the light emitter. However, they generally cannot track on glossy and transparent surfaces, including some mouse-pads, sometimes causing the cursor to drift unpredictably during operation. Mice with less image-processing power also have problems tracking fast movement, though high-end mice can track at 2 m/s (80 inches per second) and faster.

Some models of laser mice can track on glossy and transparent surfaces, and have a much higher sensitivity than either their mechanical or optical counterparts. Such models of laser mice cost more than LED based or mechanical mice.[27]

As of 2006, mechanical mice have lower average power demands than their optical counterparts. This typically has no practical impact for users of cabled mice (except possibly those used with battery-powered computers, such as notebook models), but has an impact on battery-powered wireless models.

Optical models will outperform mechanical mice on uneven, slick, soft, sticky, or loose surfaces, and generally in mobile situations lacking mouse pads. Because optical mice render movement based on an image which the LED (or infared diode) illuminates, use with multi-colored mouse pads may result in unreliable performance; however, laser mice do not suffer these problems and will track on such surfaces. The advent of affordable high-speed, low-resolution cameras and the integrated logic in optical mice provides an ideal laboratory for experimentation on next-generation input-devices. Experimenters can obtain low-cost components simply by taking apart a working mouse and changing the optics or by writing new software.

[edit] Inertial mice

Inertial mice use a tuning fork or other accelerometer (US Patent 4787051) to detect movement 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. A patent for an inertial mouse claims that such mice consume less power than optically based mice, and offer increased sensitivity, reduced weight and increased ease-of-use.[28]

[edit] 3D mice

Also known as flying mice, bats, or wands, these devices generally function through ultrasound. Probably the best known example would be 3DConnexion/Logitech's SpaceMouse from the early 1990s.

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.[29] Despite a certain appeal, it was finally discontinued because it did not provide sufficient resolution.

A recent consumer 3D pointing device is the Wii Remote. While primarily a motion-sensing device (that is, it can determine its orientation and direction of movement), Wii Remote can also detect its spatial position by comparing the distance and position of the lights from the IR emitter using its integrated IR camera (since the nunchuk lacks a camera, it can only tell its current heading and orientation). The obvious drawback to this approach is that it can only produce spatial coordinates while its camera can see the sensor bar.

In February, 2008, at the Game Developers' Conference (GDC), a company called Motion4U introduced a 3D mouse add-on called "OptiBurst" for Autodesk's Maya application. The mouse allows users to work in true 3D with 6 degrees of freedom.[citation needed] The primary advantage of this system is speed of development with organic (natural) movement.

[edit] Double mouse system

The double mouse system allows two mice to be used at once as input devices such as when operating various graphics and multimedia applications.[30]

[edit] 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), although many such cordless interfaces are themselves connected through the aforementioned wired serial buses.

While the electrical interface and the format of the data transmitted by commonly available mice is currently standardized on USB, in the past it varied between different manufacturers. A bus mouse used a dedicated interface card for connection to an IBM PC or compatible computer.

[edit] Serial interface and protocol

Standard PC mice once used the RS-232C serial port via a D-subminiature connector, which provided power to run the mouse's circuits as well as data on mouse movements. The Mouse Systems Corporation version used a five-byte protocol and supported three buttons. The Microsoft version used an incompatible three-byte protocol and only allowed for two buttons. Due to the incompatibility, some manufacturers sold serial mice with a mode switch: "PC" for MSC mode, "MS" for Microsoft mode.[31]

[edit] PS/2 interface and protocol

For more details on this topic, see PS/2 connector.

With the arrival of the IBM PS/2 personal-computer series in 1987, IBM introduced the eponymous PS/2 interface for mice and keyboards, which other manufacturers rapidly adopted. 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.[32] For any motion, button press or button release event, a PS/2 mouse sends, over a bi-directional serial port, a sequence of three bytes, with the following format:

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Byte 2 X movement
Byte 3 Y movement

Here, XS and YS represent the sign bits of the movement vectors, XV and YV indicate an overflow in the respective vector component, and LB, MB and RB indicate the status of the left, middle and right mouse buttons (1 = pressed). PS/2 mice also understand several commands for reset and self-test, switching between different operating modes, and changing the resolution of the reported motion vectors.

In Linux, a PS/2 mouse is detected as a /dev/psaux device.

[edit] Extensions: IntelliMouse and others

A Microsoft IntelliMouse relies on an extension of the PS/2 protocol: the ImPS/2 or IMPS/2 protocol (the abbreviation combines the concepts of "IntelliMouse" and "PS/2"). 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 in which 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).[33]

The Typhoon mouse uses 6-byte packets which can appear as a sequence of two standard 3-byte packets, such that ordinary PS/2 driver can handle them.[34]

Mouse-vendors also use other extended formats, often without providing public documentation.

For 3D or 6DOF input, vendors have made many extensions both to the hardware and to software. In the late 90's Logitech created ultrasound based tracking which gave 3D input to a few millimeters accuracy, which worked well as an input device but failed as a money making product. In 2008, Motion4U introduced its "OptiBurst" system using IR tracking for use as a Maya plugin.

[edit] Apple Desktop Bus

Apple Macintosh Plus mice, 1986.

In 1986 Apple first implemented the Apple Desktop Bus allowing the daisy-chaining together of up to 16 devices, including arbitrarily many mice and other devices on the same bus with no configuration whatsoever. 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 (including a number of non-Apple workstations) until 1998 when iMac began the industry-wide switch to using USB. Beginning with the "Bronze Keyboard" PowerBook G3 in May 1999, Apple dropped the external ADB port in favor of USB, but retained an internal ADB connection in the PowerBook G4 for communication with its built-in keyboard and trackpad until early 2005.

[edit] Tactile mice

In 2000, Logitech introduced the "tactile mouse", which contained a small actuator that made the mouse vibrate. Such a mouse can augment user-interfaces with haptic feedback, such as giving feedback when crossing a window boundary. To surf by touch requires the user to be able to feel depth or hardness; this ability was realized with the first electrorheological tactile mice[35] but never marketed.

[edit] Applications of mice in user-interfaces

Computer-users usually utilize a mouse to control the motion of a cursor in two dimensions in a graphical user interface. Clicking or hovering can select files, programs or actions from a list of names, or (in graphical interfaces) through pictures called "icons" and other elements. For example, a text file might be represented by a picture of a paper notebook, and clicking while the pointer hovers this icon might cause a text editing program to open the file in a window. (See also point-and-click)

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. The user releases the mouse button

For example, a user might drag-and-drop a picture representing a file onto a picture of a trash-can, thus instructing the system to delete the file.

Other uses of the mouse's input occur commonly in special application-domains. In interactive three-dimensional graphics, the mouse's motion often translates directly into changes in the virtual camera's orientation. For example, in the first-person shooter genre of games (see below), players usually employ the mouse to control the direction in which the virtual player's "head" faces: moving the mouse up will cause the player to look up, revealing the view above the player's head.

When mice have more than one button, software may assign different functions to each button. Often, the primary (leftmost in a right-handed configuration) button on the mouse will select items, and the secondary (rightmost in a right-handed) button will bring up a menu of alternative actions applicable to that item. For example, on platforms with more than one button, the Mozilla web browser will follow a link in response to a primary button click, will bring up a contextual menu of alternative actions for that link in response to a secondary-button click, and will often open the link in a new tab or window in response to a click with the tertiary (middle) mouse button.

[edit] Common mouse operations

Performing different operations on the mouse provide the activation of specific actions on the interface, with different meanings. GUIs may define and trigger a separate event for each gesture.

[edit] Low level gestures

  • Click - pressing and releasing a button.
  • Drag - pressing and holding a button, then moving the mouse without releasing.
    • (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.
  • 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 with a modifier key.

[edit] Standard semantic gestures

[edit] Buttons

In contrast to the motion-sensing mechanism, the mouse's buttons have changed little over the years, varying mostly in shape, number, and placement. Engelbart's very first mouse had a single button; Xerox PARC soon designed a three-button model, but reduced the count to two for Xerox products. After experimenting with 4-button prototypes Apple reduced it back to one button with the Macintosh in 1984, while Unix workstations from Sun and others used three buttons. OEM bundled mice usually have between one and three buttons, although in the aftermarket many mice have always had five or more.

Apple Mighty Mouse with capacitance triggered buttons

A mouse click is the action of pressing (i.e. 'clicking', an onomatopoeia) a button in order to trigger an action, usually in the context of a graphical user interface (GUI). 'Clicking' an onscreen button is accomplished by pressing on the real button mouse while the cursor is placed over the widget.

The reason for the clicking noise made is due to the specific switch technology used nearly universally in computer mice. This switch is called a micro switch or cherry switch and uses a stiff but flexible metal strip that is bent to actuate the switch. The bending of the metal makes a snapping or clicking noise.

The three-button scrollmouse has become the most commonly available design. As of 2007 (and roughly since the late 1990s), users most commonly employ the second button to invoke a contextual menu in the computer's software user interface, which contains options specifically tailored to the interface element over which the mouse pointer currently sits. By default, the primary mouse button sits located on the left-hand side of the mouse, for the benefit of right-handed users; left-handed users can usually reverse this configuration via software.

On systems with three-button mice, pressing the center button (a middle click) typically opens a system-wide noncontextual menu. In the X Window System, middle-clicking by default pastes the contents of the primary buffer at the pointer's position. Many users of two-button mice emulate a three-button mouse by clicking both the right and left buttons simultaneously.

[edit] One, two, three or more buttons?

One button mouse
Three-button mouse
Five button mouse

The issue of whether pack-in bundled mice "should" have exactly one button or more than one has attracted an enormous amount of controversy. From the first Macintosh until late 2005 Apple shipped every computer with a single-button mouse, whereas most other platforms used multi-button mice. Apple and its advocates promoted single-button mice as more user-friendly, and portrayed multi-button mice as confusing for novice users. The Macintosh user interface, by design, always has and still does make all functions available with a single-button mouse. Apple's Human Interface Guidelines still specify that all software-providers need to make functions available with a single button mouse. However, X Window System applications, which Mac OS X can also run, have developed with the use of two-button or even three-button mice in mind, causing even simple operations like "cut and paste" to become awkward on the Macintosh.

While there has always been an aftermarket for mice with two, three, or more buttons among experienced Macintosh users and extensive configurable support to complement such devices in all major software packages on the platform, Mac OS X shipped with hardcoded support for multi-button mice. On August 2, 2005, Apple introduced their Mighty Mouse multi-button mouse, which has four independently-programmable buttons and a trackball-like "scroll ball" which allows the user to scroll in any direction. Since the mouse uses touch-sensitive technology, users can treat it as a one-, two-, three-, or four-button mouse, as desired.

Advocates of multiple-button mice argue that support for a single-button mouse often leads to clumsy workarounds in interfaces where a given object may have more than one appropriate action. One workaround was the double click, first used on the Apple Lisa, to allow both the "select" and "open" operation to be performed with a single button. Several common workarounds exist, and some are specified by the Apple Human Interface Guidelines.

One such workaround (that favored on Apple platforms) has the user hold down one or more keys on the keyboard before pressing the mouse button (typically control on a Macintosh for contextual menus). This has the disadvantage that it requires that both the user's hands be engaged. It also requires that the user perform actions on completely separate devices in concert; that is, holding a key on the keyboard while pressing a button on the mouse. This can be a difficult task for a disabled user, although can be remedied by allowing keys to stick so that they do not need to be pressed down.

Another involves the press-and-hold technique. In a press-and-hold, the user presses and holds the single button. After a certain period, software perceives the button press not as a single click but as a separate action. This has two drawbacks: first, a slow user may press-and-hold inadvertently. Second, the user must wait for the software to detect the click as a press-and-hold, otherwise the system might interpret the button-depression as a single click. Furthermore, the remedies for these two drawbacks conflict with each other: the longer the lag time, the more the user must wait; and the shorter the lag time, the more likely it becomes that some user will accidentally press-and-hold when meaning to click. Studies have found all of the above workarounds less usable than additional mouse buttons for experienced users.[citation needed]

Most machines running Unix or a Unix-like operating system run the X Window System which almost always encourages a three-button mouse. X numbers the buttons by convention. This allows user instructions to apply to mice or pointing devices that do not use conventional button placement. For example, a left-handed user may reverse the buttons, usually with a software setting. With non-conventional button placement, user directions that say "left mouse button" or "right mouse button" are confusing. The ground-breaking Xerox Parc Alto and Dorado computers from the mid-1970s used three-button mice, and each button was assigned a color. Red was used for the left (or primary) button, yellow for the middle (secondary), and blue for the right (meta or tertiary). This naming convention lives on in some SmallTalk environments, such as Squeak, and can be less confusing than the right, middle and left designations.

Acorn's RISC OS based computers necessarily use all three mouse buttons throughout their WIMP based GUI. RISC OS refers to the three buttons (from left to right) as Select, Menu and Adjust. Select functions in the same way as the "Primary" mouse button in other operating systems. Menu will bring up a context-sensitive menu appropriate for the position of the mouse pointer, and this often provides the only means of activating this menu. This menu in most applications equates to the "Application Menu" found at the top of the screen in Mac OS, and underneath the window title under Microsoft Windows. Adjust serves for selecting multiple items in the "Filer" desktop, and for altering parameters of objects within applications — although its exact function usually depends on the programmer.

[edit] Additional buttons

Aftermarket manufacturers have long built mice with five or more buttons. Depending on the user's preferences and software environment, the extra buttons may allow forward and backward web-navigation, scrolling through a browser's history, or other functions, including mouse related functions like quick-changing the mouse's resolution/sensitivity. As with similar features in keyboards, however, not all software supports these functions. The additional buttons become especially useful in computer games, where quick and easy access to a wide variety of functions (for example, weapon-switching in first-person shooters) can give a player an advantage. Because software can map mouse-buttons to virtually any function, keystroke, application or switch, extra buttons can make working with such a mouse more efficient and easier.

In the matter of the number of buttons, Douglas Engelbart favored the view "as many as possible". The prototype that popularised the idea of three buttons as standard had that number only because "we could not find anywhere to fit any more switches".

[edit] Wheels

The scroll wheel, a notably different form of mouse-button, consists of a small wheel that the user can rotate to provide immediate one-dimensional input. Usually, this input translates into "scrolling" up or down within the active window or GUI-element. The wheel is often - but not always - engineered to turn in short steps, rather than continuously, to allow the operator to more easily intuit how far they are scrolling. The scroll wheel nearly always includes a third (center) button, activated by pushing the wheel down into the mouse.

The scroll wheel can provide convenience, especially when navigating a long document. In conjunction with the control key (Ctrl), the mouse wheel may often be used for zooming in and out; applications that support this feature include Adobe Reader, Microsoft Word, Internet Explorer, Opera, Mozilla Firefox and Mulberry, and in Mac OS X, holding the control key while scrolling zooms in on the entire screen. Some applications also allow the user to scroll left and right by pressing the shift key while using the mouse wheel.

Manufacturers may refer to scroll-wheels by different names for branding purposes; Genius, for example, usually brand their scroll-wheel-equipped products "Netscroll".

Mouse Systems introduced the scroll-wheel commercially in 1995,[36] marketing it as the Mouse Systems ProAgio and Genius EasyScroll. However, mainstream adoption of the scroll wheel mouse did not occur until Microsoft released the Microsoft IntelliMouse in 1996. It became a commercial success in 1997 when their Microsoft Office application suite and their Internet Explorer browser started supporting its wheel-scrolling feature.[36] Since then the scroll wheel has become a standard feature of many mouse models.

Some mouse models have two wheels, or wheels that can be moved sideways (such as the MX Revolution), separately assigned to horizontal and vertical scrolling. Designs exist which make use of a "rocker" button instead of a wheel — a pivoting button that a user can press at the top or bottom, simulating "up" and "down" respectively. A peculiar early example was a mouse by Saitek which had a joystick-style hatswitch on it.[citation needed]

A more recent form of mouse wheel is the tilt-wheel. Tilt wheels are essentially conventional mouse wheels that have been modified with a pair of sensors articulated to the tilting mechanism. These sensors are mapped, by default, to horizontal scrolling.

A third variety of built-in scrolling device, the scroll ball, essentially consists of a trackball embedded in the upper surface of the mouse. The user can scroll in all possible directions in very much the same way as with the actual mouse, and in some mice, can use it as a trackball. Mice featuring a scroll ball include Apple's Mighty Mouse and the IOGEAR 4D Web Cruiser Optical Scroll Ball Mouse. IBM's ergonomics laboratory designed a mouse with a pointing stick in it,[37] envisioned to be used for scrolling, zooming or (with appropriate software) controlling a second mouse cursor.

[edit] Mouse speed

The computer industry often measures mouse sensitivity in terms of counts per inch (CPI), commonly expressed less correctly as dots per inch (DPI) — the number of steps the mouse will report when it moves one inch. In early mice, this specification was called pulses per inch (ppi).[11] If the default mouse-tracking condition involves moving the pointer by one screen-pixel or dot on-screen per reported step, then the CPI does equate to DPI: dots of pointer motion per inch of mouse motion. The CPI or DPI as reported by manufacturers depends on how they make the mouse; the higher the CPI, the faster the pointer moves with mouse movement. However, software can adjust the mouse sensitivity, making the cursor move faster or slower than its DPI. Current software can change the speed of the pointer dynamically, taking into account the mouse's absolute speed and the movement from the last stop-point. Different software may name the settings "acceleration" or "speed" — referring respectively to "threshold" and "pointer precision".

For simple software, when the mouse starts to move, the software will count the number of "counts" received from the mouse and will move the pointer across the screen by that number of pixels (or multiplied by a factor f1=1,2,3). So, the pointer will move slowly on the screen, having a good precision. When the movement of the mouse reaches the value set for "threshold", the software will start to move the pointer more quickly; thus for each number n of counts received from the mouse, the pointer may move (f2 x n) pixels, where f2=2,3...10. Usually, the user can set the value of f2 by changing the "acceleration" setting.

Operating systems sometimes apply acceleration, referred to as "ballistics", to the motion reported by the mouse. For example, versions of Windows prior to Windows XP doubled reported values above a configurable threshold, and then optionally doubled them again above a second configurable threshold. These doublings applied separately in the X and Y directions, resulting in very nonlinear response. For example one can see how the things work in Microsoft Windows NT. Starting with Windows XP OS version of Microsoft and many OS versions for Apple Macintosh, computers use a smoother ballistics calculation that compensates for screen-resolution and has better linearity.

[edit] Accessories

[edit] Mousepad

Main article: Mousepad

Engelbart's original mouse did not require a mousepad;[38] the mouse had two large wheels which could roll on virtually any surface. However, most subsequent mice starting with the steel roller ball mouse have needed mousepads in order to perform effectively.

The mousepad, the most common mouse accessory, appears most commonly in conjunction with mechanical mice, because in order to roll smoothly, the ball requires more friction than common desk surfaces usually provide. So-called "hard mousepads" for gamers or optical/laser mice also exist.

Although most optical and laser mice do not require a pad, some users find that using a mousepad provides more comfort and less jitter of the pointer on the display.[citation needed] Whether to use a hard or soft mousepad with an optical mouse is largely a matter of personal preference. One exception occurs when the desk surface creates problems for the optical or laser tracking, for example, a transparent or reflective surface. Other cases may involve keeping desk or table surfaces free of scratches and deterioration; when the grain pattern on the surface causes inaccurate tracking of the pointer, or when the mouse-user desires a more comfortable mousing surface to work on and reduced collection of debris under the mouse.[citation needed]

[edit] Foot covers

Mouse foot-covers (or foot-pads) consists of low-friction or polished plastic. This makes the mouse glide with less resistance over a surface. Some higher quality models have teflon feet to reduce friction even further.

[edit] Mice in the marketplace

Around 1981 Xerox included mice with its Xerox Star, based on the mouse used in the 1970s on the Alto computer at Xerox PARC. Sun Microsystems, Symbolics, Lisp Machines Inc., and Tektronix also shipped workstations with mice, starting in about 1981. Later, inspired by the Star, Apple Computer released the Apple Lisa, which also used a mouse. However, none of these products achieved large-scale success. Only with the release of the Apple Macintosh in 1984 did the mouse see widespread use.

The Macintosh design, commercially successful and technically influential, led many other vendors to begin producing mice or including them with their other computer products (in 1985, Atari ST, Commodore Amiga, Windows 1.0, and GEOS for the Commodore 64). The widespread adoption of graphical user interfaces in the software of the 1980s and 1990s made mice all but indispensable for controlling computers.

[edit] Mice in gaming

Mice often function as an interface for PC-based computer games and sometimes for video game consoles. They often appear in combination with the keyboard.

[edit] First-person shooters

Logitech G5 Laser Mouse designed for gaming.

Due to the cursor-like nature of the crosshairs in shooter games, a combination of mouse and keyboard provides a popular way to play first-person shooter (FPS) games. Players use the X-axis of the mouse for looking (or turning) left and right, leaving the Y-axis for looking up and down. The left button usually controls primary fire. Many gamers prefer this over a gamepad or joystick because it allows them to look around easily, quickly and accurately and also as a consequence aim without auto-aim assist. If the game supports multiple fire-modes, the right button often provides secondary fire from the selected weapon. Secondary weapons include grenades, knives, etc. The right button may also provide bonus options for a particular weapon, such as allowing access to the scope of a sniper rifle or allowing the mounting of a bayonet or silencer or sometimes even jumping.

Gamers can use a scroll wheel for changing weapons, or for controlling scope-zoom magnification. On most FPS games, programming may also assign more functions to additional buttons on mice with more than three controls. A keyboard usually controls movement (for example, WASD, for moving forward, left, backward and right, respectively) and other functions such as changing posture. Since the mouse serves for aiming, a mouse that tracks movement accurately and with less lag (latency) will give a player an advantage over players with less accurate or slower mice.

An early technique of players, circle-strafing, saw a player continuously strafing while aiming and shooting at an opponent by walking in circle around the opponent with the opponent at the center of the circle. Players could achieve this by holding down a key for strafing while continuously aiming the mouse towards the opponent.

Games using mice for input have such a degree of popularity that many manufacturers, such as Logitech, and Razer USA Ltd, make peripherals such as mice and keyboards specifically for gaming. Such devices frequently feature (in the case of mice) adjustable weights, high-resolution optical or laser components, additional buttons, ergonomic shape, and other features such as adjustable DPI.

[edit] Invert mouse setting

Many games, such as first- or third-person shooters, have a setting named "invert mouse" or similar (not to be confused with "button inversion", sometimes performed by left-handed users) which allows the user to look downward by moving the mouse forward and upward by moving the mouse backward (the opposite of non-inverted movement). This control system resembles that of aircraft control sticks, where pulling back causes pitch up and pushing forward causes pitch down; computer joysticks also typically emulate this control-configuration.

After id Software's Doom, the game that popularized FPS games but which did not support vertical aiming with a mouse (the y-axis served for forward/backward movement), competitor 3D Realms' Duke Nukem 3D became one of the first games that supported using the mouse to aim up and down. It and other games using the Build engine had an option to invert the Y-axis. The "invert" feature actually made the mouse behave in a manner that users now regard as non-inverted (by default, moving mouse forward resulted in looking down). Soon after, id Software released Quake, which introduced the invert feature as users now know it. Other games using the Quake engine have come on the market following this standard, likely due to the overall popularity of Quake.

[edit] Home consoles

In 1988 the educational video game system, the VTech Socrates, featured a wireless mouse with an attached mouse pad as an optional controller used for some games. In the early 1990s the Super Nintendo Entertainment System video game system featured a mouse in addition to its controllers. The Mario Paint game in particular used the mouse's capabilities, as did its successor on the N64. Sega released official mice for their Genesis/Mega Drive, Saturn and Dreamcast consoles. Sony Computer Entertainment released an official mouse product for the PlayStation console, and included one along with the Linux for PlayStation 2 kit. However, users can attach virtually any USB mouse to the PlayStation 2 console. In addition the PlayStation 3, and Xbox 360 also support USB mice. Recently the Wii also has this latest development added on in a recent software update.

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