Video system with picture information and logic signal multiplexing

摘要

A color video signal generator includes means for selectively generating either color difference information or logic levels from the same output pins. The color video signal generator is employed in a video system which outputs either the internally generated video signal or an externally generated video signal depending on whether the color difference information or the logic levels are generated. This invention has application to video terminals and small computing systems which employ video displays to enable selective display of internally generated pictures or externally generated pictures or selective overlap of such pictures. This invention also has application to integrated circuit pin minimization by enabling an analog and a digital signal to be multiplexed on the same pin.