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jsgroth / jgenesis

Sega Genesis / Sega CD / SNES / Master System / Game Gear emulator
MIT License
48 stars 3 forks source link

Demo "Mind Control Trilogy Preview.nes messed up graphics #82

Open benderscruffy opened 4 months ago

benderscruffy commented 4 months ago

mind_control_trilogy_preview_by_bilotrip.zip

jsgroth commented 4 months ago

Part of the issue is that this demo appears to depend on PAL video timings, but the iNES header doesn't specify a video mode so the emulator defaults to NTSC. With timing/display mode forced to PAL the demo looks pretty similar to this recording: https://www.youtube.com/watch?v=4TROWubW83s

Aside from that, this demo uses the VRC6 mapper and its behavior varies based on initial VRC6 state because it never writes to any VRC6 registers aside from the VRC6 audio registers. The graphics look a bit less glitched if I default the $C000-$DFFF PRG ROM bank to 2 instead of 0 and also default the eight CHR ROM banks to 0-7 instead of all 0. None of the three VRC6 games rely on initial VRC6 state so this should be a safe change to make.