I am surprised no-one put any kind of extra processing power into a NES mapper, we saw extra sound added (VRC7 etc).
The unreleased color dreams 'hellraiser' cart had a z80 on it. It suffered from excessive cost due to z80 and extra memory on it, and had timing issues and vram contention issues. It supposedly was a fairly awesome wolf3d style shooter though, iirc.
LN
