Here is the patch I made which enhances the Super Mario Bros. ROM, and makes it more hacker-friendly.Taken from Readme:
- The ROM has been converted to Mapper 4: MMC3.
- In order to do the mapper conversion, the ROM had to be expanded. The PRG-ROM size has been doubled.
- Full mapper preparation and SRAM support. The MMC3 mapper has been fully prepped, and SRAM has been enabled. Not only can you now do SRAM hacks to this game, it should run fine on real hardware.
- CHR-ROM Swapping programmed. Super Mario Bros. only had one CHR-ROM page, but because of that, it didn't have a CHR-ROM Swapping routine. I programmed one in there. And just for the heck of it, I added an extra CHR-ROM page. You can add a lot more if you need to.Please see readme for full details.
EDIT - Two things I forgot to include in the readme:
Bankswitch Routine is at $F290
CHR-ROM Switch Routine is at $F2AA