A 170-MHz CMOS pixel processor for windowing graphics

A pixel-processing RAMDAC chip, in 1.5- mu m CMOS, has been designed, tested, and operated at a clock rate of over 170 MHz. The authors describe the design methodology, pipelined architecture, and delay-matched circuitry used to create the block (about 38,000 transistors) which processes the pixel words. This block provides the flexible pixel-by-pixel data manipulation needed to solve several problems encountered in windowing graphics systems of one million or more pixels per frame. The circuitry can interpret each input pixel word differently, allowing a distinct visual type and color map to be assigned to each window. Previous high-performance RAMDACs have provided only one visual type and color mapping for an entire screen, causing the colors in all but the active window to be corrupted.<
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