IMAGE MANIPULATION WITH A COLOUR PALETTE CHIP.

In an effort to reduce the memory required for direct implementation of a bit-mapped colour graphics system, a compromise is often accepted to display only a limited subset of the total available colours. The hardware used to map the data in the frame buffer onto the colour display is called a colour palette, which is a RAM used as a lookup table in a manner similar to table-driven indirect addressing. Following this approach, the Am8151 graphics colour palette saves board space by replacing a large number of ECL packages with three 40-pin packages, one for each colour gun, red, green, and blue. The chip's architecture, based on a pipeline structure, minimises interfacing constraints with the RAM and the video D-to-A converters driven by the output of the lookup table.