light pen: a pen-shaped object with a light-sensitive cell at one end, used as an
alternative to the keyboard to communicate with the screen's electronics.
Figure 2-30. Graphic display device with light pen used in computerized
3-dimensional car design.
Figure 2-31. Composing music with a light pen.
(3) Sound synthesizers provide voice, tone, or musical feedback. The
banking industry uses this approach to report customer account balances. Often the
audio response units are coupled with touch tone terminals for review of the data entry