Patent ID: 7095909

Claim:
A system for forming an image on a display screen scanned in frames by a beam, comprising: a light pen which can be pointed at different points on the screen and has a light sensing element for providing a signal when the position of the light pen coincides with the position of the beam, a display memory having a plurality of addressable storage locations, an object memory containing data for an object to be controlled by the light pen, means responsive to the signal from the light pen for reading data out of the object memory in synchronism with the scanning of the beam, means for writing the data read out of the object memory into the display memory at locations corresponding to the position of the light pen on the screen during successive frames, means for addressing the display memory locations, means for reading the data out of the display memory locations as they are addressed, and means responsive to the data read out of the display memory for producing an image of the object on the screen at points where the light pen is pointed during successive frames.