INES Mapper 001

iNES Mapper 001 is used to designate the SxROM boardset, all of which use the Nintendo MMC1.

This has proven to be problematic for boards (such as SOROM, SUROM and SXROM) which use the upper CHR bank select lines to select additional PRG ROM or PRG RAM data; games which use SOROM or SXROM often must be handled individually based on the ROM checksum.

In the absence of data beyond basic iNES header data, the following procedure may work to guess a board type useful for emulation:

1. PRG ROM size equal to 512 KiB: SUROM
2. CHR ROM not present: SNROM (It should be okay to have SOROM's registers avaliable for compatability without a checksum, as long as the game doesn't try to write to them)
3. Else: SKROM