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SNES Coprocessors: DSP-1 and Friends

While Sega tried to expand the Genesis’ capabilities by adding on to the console hardware with the Sega CD and 32X, Nintendo took a different approach with the SNES: put additional hardware into the cartridge on a game-by-game basis. This post will cover the first SNES coprocessor, DSP-1, and its close relatives.

Pilotwings and Super Mario Kart both use the SNES PPU’s Mode 7 to render their faux-3D graphics with perspective, but they rely very heavily on the DSP-1 to perform the 3D calculations required for each frame. Original DSP-1 and DSP-1A seem to be identical other than minor hardware differences, while DSP-1B modifies the program ROM to fix a bug in one of the math functions. It’s backwards-compatible with the μPD77C25 while supporting higher memory capacity, a battery backup for data RAM, and a few additional instructions (mainly jumps).

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