The VT09 variant of the OneBus-type Famiclones has 4 KiB instead of 2 KiB of main CPU RAM at offset $0000 in CPU memory. FCEUX apparently uses mapper 256 for OneBus, and I intend to follow that precedent. In the NES 2.0 format, should this additional RAM be denoted as a submapper or as 2 KiB PRG-RAM, even though this additional RAM is part of the main unit (or rather part of the main chip) and not the game? Some OneBus images of course have the normal 8 KiB of WRAM at $6000, so if one went for the PRG-RAM field, the PRG-RAM size would then implicitly determine its offset as well, which seems kind of hacky to me. Given that several OneBus images are multicarts consisting of NES-era games that may depend on RAM being mirrored four times in the $0000-$1FFF range, just always emulating the additional 2 KiB does not seem safe.
Opinions?
Opinions?