nesdev.org

I have successfully applied game Genie codes to all NSFs that I wanted except for Super Mario Bros and Super Mario Bros. 3. Is there an extra step for these games that needs to be taken?

Those games don't have their sound screwed up by the real Game Genie, do they? If you deliberately want to screw up the music, you could, but... why?

Yes they do. Codes like PPPPPP don't work on the Super Mario Bros. 1 nsf and for Super Mario Bros. 3 ZKIPEE, SKIPEA, EAGVIT, KLOTOE don't work when patched.

OKEATS does not work when patched into Super Mario Bros. 2 but all other codes I've tried work like they do on hardware.

I've also ran into yet another problem... when a value for the Game Genie code is higher then the nsf permits due to the smaller initial size of the nsf, I have no idea on what to do. Do I subtract the value to the offset of the missing PRG data and if so, I would have to basically rip the nsf to find where the music code is, right?

I just checked PPPPPP for SMB 1. The reason it won't work is because that's in the song init routine, and the song init routine is now custom coding in a new location.

SMB 2 OKEATS:
40 AD 09 06 > 40 AD C9 06

SMB 3 ZKIPEE, SKIPEA:
Both of these hack the same byte of the music init routine. NSF hacks the value to be whatever the user chooses it to be. Useless to apply.

SMB 3 EAGVIT:
AE F8 07 > AE F8 80

SMB 3 KLOTOE:
F2 07 A5 6E > F2 07 A5 BC


To apply these, I just decoded the GG code, put read and execute on a range of address-3 to address in the debugger, and found the likely or only bytes being affected. Once I could see the spot in question, I recorded the bytes, and added more searchable bytes before and after the changed spot until searching for it in the file resulted in only 1 matching address.

With OKEATS patched into Super Mario Bros. 2, I got that same result the first time around; The nsf should have been locked into sample mode but instead, it's locked into hard drum mode.

The Super Mario Bros. 3 codes worked.
Thanks!

SMB2 relies on some graphics data, I think. Here's a mod that does the same thing(not having tested it much)

SMB 2 OKEATS Alternate:
40 AD 09 06 > 40 A9 EE EA

Cool, thanks, again.