Abstract: System and method for forming an operator controlled image on a video display screen with a light sensing pen. The pen is moved relative to the screen to provide a signal corresponding to the position of the pen during each successive frame of the display. A memory having a plurality of data storage locations corresponding to different points on the screen is scanned in synchronization with the position of the beam, and data is written into the memory in response to the signal from the light pen at locations corresponding to the points at which the light pen senses the bean during successive frames. This data is read out of the memory as it is scanned and is utilized to produce an image corresponding to the position of the light pen in successive frame.