Abstract: A position sensing system calculates the X-Y coordinates of a point using triangulation and determines the direction in which the point is moving. The triangulation calculation is based on the coordinates of at least three retroreflective elements spaced apart from each other around the periphery of a two-dimensional coordinate frame, and the measured angles between the lines projected radially outward from the point to each of the retroreflective elements. The accuracy of the measured angles is achieved by using a rotating member supported by dedicated hardware and controlled by software. The member rotates with a beam of light generated by a light transmitting and detecting device positionable at the point. The light transmitting and detecting device receives the beam of light reflected back from the retroreflective elements and generates an output signal in response thereto.