Abstract: A bidirectional multispeed indexing control system for a display unit which has an increment input and a decrement input so as to be controllable to sequentially index through an ordered list of discrete elements. The control system has a two-button user interface. The user presses one button to increment once, and holds that button to continuously index at a slow fixed speed. To increase the indexing speed, the user presses the second button while continuing to hold the first button. Indexing speed will continue to increase until either a maximum speed is reached or the user releases the second button, at which point the indexing speed decreases from the value reached while holding the second button. To stop indexing, both buttons are released. To increment in the opposite direction (i.e., decrement), the order in which the buttons are pressed is reversed.