Method and apparatus for combining video images on a pixel basis

摘要

A method and apparatus for raster-scanned video graphics systems where clocked digital video words from a plurality of sources are combined so that, at each video clock time, a word is chosen from one of the ports to light the current pixel on a display. There is an input port for each video source and a gate associated with each input port for passing or inhibiting a binary word. A decision at each video clock time chooses a word from one of the ports and passes it to an output port which leads to a video display or palette device. This decision is based on the data content of the current digital video words at the input ports.