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[SOLVED] Emulating Mapper 225 (64-in-1 rom) question.
http://forums.nesdev.com/viewtopic.php?f=3&t=14515
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Author:  Fumarumota [ Sat Jul 09, 2016 8:42 pm ]
Post subject:  [SOLVED] Emulating Mapper 225 (64-in-1 rom) question.

Hi guys,

I've almost completed this mapper and I'm testing it with the "64-in-1" ROM, but I've run into some strange problem:

Every game in the list works except for B-Wings. This game alone is mapper 185, which I currently support right now and I've got it running just fine.

When running B-Wings from the 64 in 1 cart menu, I just get a blue screen (as if the copy protection mechanism wasn't emulated correctly, and the game was locked). As far as I know, the games on this multi cart are hacked to be NROM / CNROM compatible, so nothing special seems to be necessary to emulate it correctly.

Could it be something I'm missing?

Thanks again for your help in advance.

Author:  Fumarumota [ Thu Jul 14, 2016 8:17 pm ]
Post subject:  Re: Emulating Mapper 225 (64-in-1 rom) question.

Hey guys,

Nevermind. We found out we were handling writes to PPU $0000-$1FFF region in a wrong way. Writes were not inhibited when not CHR RAM (CHR ROM was being corrupted and strange things were happening), and it turns out that B-Wings makes some writes to that region.

Added that check to our PPU CHR write handler and everything is working just fine.

Thanks!

Author:  Zepper [ Sat Jul 16, 2016 10:02 am ]
Post subject:  Re: [SOLVED] Emulating Mapper 225 (64-in-1 rom) question.

Cowboy kid and Fantasy Zone 2 also have this problem.

Plus, try Ms. Pac Man - it writes to $8000-$FFFF when it shouldn't! :roll:

Author:  aLaix [ Sun Jul 17, 2016 10:28 am ]
Post subject:  Re: [SOLVED] Emulating Mapper 225 (64-in-1 rom) question.

I tried them a little and they looked OK! Thanks Zepper!

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