A pointing stick is a small analog stick used as a pointing device typically mounted centrally in a computer keyboard. Like other pointing devices such as mice, touchpads or trackballs, operating system software translates manipulation of the device into movements of the pointer on the computer screen. Unlike other pointing devices, it reacts to sustained force or strain rather than to gross movement, so it is called an "isometric" pointing device. IBM introduced it commercially in 1992 on the ThinkPad 700 series under the name "TrackPoint", and patented an improved version of it in 1997. It has been used for business laptops, such as Acer's TravelMate, Dell's Latitude, HP's EliteBook and Lenovo's ThinkPad.