Mapper 111 (MMC1, not Cheapocabra)

Discuss emulation of the Nintendo Entertainment System and Famicom.

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posit
Posts: 15
Joined: Tue Oct 11, 2022 11:40 pm

Mapper 111 (MMC1, not Cheapocabra)

Post by posit »

So this mentions mapper 111 was used for a non-serialized MMC1 in a certain game.
https://www.nesdev.org/wiki/GTROM#Ninja ... ranslation

I gave it an educated guess by just reading the data as a single-write byte (masked with 0x1f) rather than 5 1-bit writes. It's working...ish... does anyone know anything else about this? Or is that the gist of it?
posit
Posts: 15
Joined: Tue Oct 11, 2022 11:40 pm

Re: Mapper 111 (MMC1, not Cheapocabra)

Post by posit »

I eventually got it to work with a little more experimentation.

For reference, in case anyone else stumbles across this when making mapper 111 compatible with that additional single MMC1-ish game:
  • Yes, it is just interpreting the data as if all serial bits were sent at once
  • As the wiki says, it must support 256kb CHR ROM instead of 128kb CHR ROIM
  • As the wiki implies but isn't stated directly, that means the data byte contains 6 bits, not 5
  • Apparently I can't write code sigh. I.e. remember to triple check for your own foolish mistakes
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Dwedit
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Re: Mapper 111 (MMC1, not Cheapocabra)

Post by Dwedit »

Was this hack made into actual cartridges, or was it just an emulator-only rom hack? It's obvious how a new mapper for rom hacks would benefit the hacker, as you wouldn't need to relocate code.
Last edited by Dwedit on Tue Dec 06, 2022 11:51 am, edited 1 time in total.
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NewRisingSun
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Re: Mapper 111 (MMC1, not Cheapocabra)

Post by NewRisingSun »

Emulator-only
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