COMPUTER GRAPHICS SYSTEM

A low cost, high performance computer graphics system. A graphics processor, capable of making memory requests is connected to a memory control unit, which controls a memory bus. Both main memory and a frame buffer memory are attached to the memory bus, thereby giving the graphics processor the capability of writing to either main memory or to the frame buffer memory. The disclosure further describes a computer graphics system, having a duplicate cache tag store accessible by the graphics system without generating traffic on the system bus; having a FIFO command buffer in main memory for temporary storage of graphics commands; having a residue buffer for the temporary storage of memory transmissions not immediately usable by the graphics processor; having a "short circuit" feature for routing graphics commands to the command processor in the minimum number of steps; having a cursor control system capable of storing cursor pattern information in, and retrieving cursor pattern information from, main memory; having a cursor bus that is reconfigurable to carry information other than cursor information; and having a frame buffer module that contains no timing or cursor control circuitry.