Multiplexor implementation for raster operations including foreground and background colors

Abstract From the Canadian patent

A multiplexor implementation of circuitry for performing Boolean raster operations in a workstation whose functions include the display of graphics images using multiple planes and having foreground and background colors. The invented circuitry includes a plane raster-op select circuit and a Boolean raster-op circuit. The plane rasterop select circuit selects a Boolean raster operation to be performed for each plane of graphics information as a function of foreground and background color control signals. The selected Boolean raster operation for each plane is then input to a set of multiplexors and the selected Boolean raster operation is performed on the control inputs to the multiplexors …