iNES Mapper 123 is used for the 卡聖 (Kǎshèng) H2288 board, an MMC3-clone-bearing board with scrambled register indices, and an NROM-like PRG-ROM register that can override the MMC3 clone's PRG-ROM bank. Its UNIF board name is UNL-H2288. Used by:
Mask: $F800 D~7654 3210 --------- .M31 .2S0 +++--+|+- Select 16 KiB PRG-ROM bank at CPU | | $8000-$BFFF and $C000-$FFFF (notice the bit order) | +-- 0: Do not replace bit 0 (NROM-128) | 1: Replace bit 0 with CPU A14 (NROM-256) +-------- 0: Use PRG bank from MMC3; ignore $5800 bits 0-3/5 1: Ignore PRG bank from MMC3; apply $5800 bits 0-3/5
$8000 index written MMC3 register meant ------------------- ------------------- 0 0 1 3 2 1 3 5 4 6 5 7 6 2 7 4
Bits 6 and 7 of the value written to $8000 are unchanged. See MMC3 for further details.
Categories: Mappers using $4020-$5FFF, Mappers with scanline IRQs, MMC3-like mappers