A writing stylus (100) having a motion sensor (204) for sensing
the
movement of at least one end 110 of the stylus relative to an adjacent surface
is described. The stylus has an elongated housing (104) and a cap (102).
The motion sensor generates signals corresponding to the relative motion of the
surface to the sensor. The cap is removeably carried on at least one portion of
the housing which also has the motion sensor. The cap comprises a light passage
(118) adapted to allow the motion sensor to sense the translation of the
surface adjacent to the cap, through the cap. In a first input mode the motion
sensor is used for sensing manual hand writing motion. In a second mode, when the
cap is carried on the housing and is placed over at least the motion sensor, the
motion sensor senses the motion of a surface adjacent to the cap such as a users
finger. In this mode, the stylus functions a multiple axis input device such as
a thumbwheel.