mouse

hardware, graphics The most commonly used computer pointingdevice, first introduced by Douglas Engelbart in 1968.

The mouse is a device used to manipulate an on-screen

pointer that's normally shaped like an arrow. With the

mouse in hand, the computer user can select, move, and change

items on the screen.

A conventional roller-ball mouse is slid across the surface

of the desk, often on a mouse mat. As the mouse moves, a

ball set in a depression on the underside of the mouse rolls

accordingly. The ball is also in contact with two small

shafts set at right angles to each other inside the mouse.

The rotating ball turns the shafts, and sensors inside the

mouse measure the shafts' rotation. The distance and

direction information from the sensors is then transmitted to

the computer, usually through a connecting wire - the mouse's

"tail". The computer then moves the mouse pointer on the

screen to follow the movements of the mouse. This may be done

directly by the graphics adaptor, but where it involves the

processor the task should be assigned a high priority to

avoid any perceptible delay.

Some mice are contoured to fit the shape of a person's right

hand, and some come in left-handed versions. Other mice are

symmetrical.

Included on the mouse are usually two or three buttons that

the user may press, or click, to initiate various actions such

as running programs or opening files. The left-most

button (the primary mouse button) is operated with the index

finger to select and activate objects represented on the

screen. Different operating systems and graphical userinterfaces have different conventions for using the other

button(s). Typical operations include calling up a

context-sensitive menu, modifying the selection, or pasting

text. With fewer mouse buttons these require combinations of

mouse and keyboard actions. Between its left and right

buttons, a mouse may also have a wheel that can be used for

scrolling or other special operations defined by the software.

Some systems allow the mouse button assignments to be swapped

round for left-handed users.

Just moving the pointer across the screen with the mouse

typically does nothing (though some CAD systems respond to

patterns of mouse movement with no buttons pressed).

Normally, the pointer is positioned over something on the

screen (an icon or a menu item), and the user then clicks

a mouse button to actually affect the screen display.

The five most common "gestures" performed with the mouse are:

point (to place the pointer over an on-screen item), click

(to press and release a mouse button), double-click topress and release a mouse button twice in rapid succession,

right-click (to press and release the right mouse button},

and drag (to hold down the mouse button while moving the

mouse).

Most modern computers include a mouse as standard equipment.

However, some systems, especially portable laptop and

notebook models, may have a trackball, touchpad or

Trackpoint on or next to the keyboard. These input

devices work like the mouse, but take less space and don't

need a desk.

Many other alternatives to the conventional roller-ball mouse

exist. A tailless mouse, or hamster, transmits its

information with infrared impulses. A foot-controlledmouse is one used on the floor

underneath the desk. An optical mouse uses a

light-emitting diode and photocells instead of a rolling

ball to track its position. Some optical designs may require

a special mouse mat marked with a grid, others, like the

Microsoft IntelliMouse Explorer, work on nearly any surface.

Yahoo!.

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PC Guide's \"Troubleshooting Mice\".

(1999-07-21)