The design of a fully integrated graphics system

The architecture and design of a CMOS chip implementing a medium-resolution graphics system are described. The chip, requiring no external support logic, outputs analog RGB signals at a 40-MHz pixel rate and directly controls a bit-map video RAM (VRAM) memory array. Scan rates and display formats are completely programmable. Pixels stored in the 1 K*1 K bit map can be any of 16 colors taken from a 4096-color palette. The chip can be directly interfaced to most common microprocessors. A 6.7-MIPS (million-instruction-per-second) internal reduced instruction set computer (RISC) CPU directly implements high-level graphics commands. The chip achieves a maximum draw speed of 10 million pixels/s. Designed in a Lisp machine environment, the 100000-transistor chip is implemented in 1.8- mu m CMOS and contains standard cells, RAM, ROM, a color table, and three four-bit current-steered digital-to-analog converters (DACs).<
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