<hardware> A pointing device consisting of a ball housed in a socket containing sensors to detect rotation of the ball about two axes - like an upside-down mouse. The user rolls the ball with his thumb or the palm of his hand to move a cursor. Tracker balls are common on CAD workstations for ease of use and on modern portable computers, where there may be no desk space on which to use a mouse. Some clip onto the side of the keyboard and have integral buttons which have the same function as mouse buttons.
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Nearby terms: trace scheduling « track « track ball « tracker ball » tracking » tracking cookie » trackpad