PROGRAMMABLE GRAPHICS PROCESSOR HAVING PIXEL TO CHARACTER CONVERSION HARDWARE FOR USE IN A VIDEO GAME SYSTEM OR THE LIKE

摘要

A fully programmable, graphics microprocessor isdisclosed which is designed to be embodied in aremovable external memory unit for connection with ahost information processing system. In an exemplaryembodiment, a video game system is describedincluding a host video game system and a pluggablevideo game cartridge housing the graphicsmicroprocessor. The game cartridge also includes aread-only program memory (ROM) and a random-accessmemory (RAM). The graphics coprocessor operates inconjunction with a three bus architecture embodied onthe game cartridge. The graphics processor usingthis bus architecture may execute programs fromeither the program ROM, external RAM or its owninternal cache RAM. The fully user programmablegraphics coprocessor has an instruction set which isdesigned to efficiently implement arithmeticoperations associated with 3-D graphics and, forexample, includes special instructions executed bydedicated hardware for plotting individual pixels inthe host video game system's character mapped displaywhich, from the programmer's point of view, creates a"virtual" bit map by permitting the addressing ofindividual pixels -- even though the host system ischaracter based. The graphics coprocessor interactswith the host coprocessor such that the graphicscoprocessor's 16 general registers are accessible tothe host processor at all times.