about mapper #197.3

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aquasnake
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Joined: Fri Sep 13, 2019 11:22 pm

about mapper #197.3

Post by aquasnake »

This mapper is mainly used for Super Fighter III conversion produced by Subor.

Sub mapper 3, assigned to 1995 super 2-in-1 (2B20). It is actually a multicart header function, the registers in $6000-$7fff are added to set the external PRG base A17 and the corresponding mask bit.

However, at present, this ROM is a bad dump, which includes two games, but the two games share one set of CHR ROM for some reason. No matter which game you choose, except for the different title and character selection interface, the other CHR resources are the same.

So I judge that either the 2-in-1 design is sharing CHR ROM, or the dump is incomplete, as newrisingsun said later.


Without By hacking the game ROM, you only need to add the 512KB CHR resources of the original Super Fighter III and add it at the end of the NES file, which can be fixed to the full version

And also, the definition of bit 0 of the register in $6000-$7fff selects both PRG A17 and CHR A19.
Last edited by aquasnake on Fri Jul 29, 2022 1:54 am, edited 4 times in total.
NewRisingSun
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Joined: Thu May 19, 2005 11:30 am

Re: about mapper #197.3

Post by NewRisingSun »

The two versions share the same 512 KiB of CHR ROM, and you cannot use the CHR ROM of the stand-alone Super Fighter III cartridge, as some graphics have been moved around to accomodate both versions. Our ROM file is not a bad dump. Screenshots of both versions can be provided on request from real hardware.
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aquasnake
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Re: about mapper #197.3

Post by aquasnake »

I have hacked this game and added an independent Super Fighter III to replace the original data

Code: Select all

An additional outer bank register at $6000-$7FFF:

Mask: $E000

D~7654 3210
  ---------
  .... S.PP
       | ++- PRG A17, A18 if S=1
       | +-- CHR A19
       +---- PRG mode
              0: PRG A17, A18=MMC3 PRG A17, A18 (512 KiB)
              1: PRG A17, A18=PP (128 KiB)
               
As the outer bank register uses the MMC3 clone's WRAM interface, writes only have an effect if WRAM is enabled and not write-protected via $A001.
1995 Super 2-in-1 (2B20) (h1) (true multicart).zip
(742.92 KiB) Downloaded 43 times
Have fun!
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