METHOD AND APPARATUS FOR COMBINING VIDEO IMAGES

摘要

A method and apparatus for raster-scanned video graphics systems where clocked digital video words (1, 2) from a plurality of sources are combined such that, at each video clock time, a word is chosen (4, 5) from one of the ports to determine the current pixel on a display. There is an input port (1, 2) for each video source and a gate (4, 5) associated with each input port for passing or inhibiting a digital word (7). A decision (3) at each video clock time chooses a word from one of the ports and passes it to an output port (7) which leads to a video display or palette device. The decision is based on the data content of the digital video words at the input ports.