NES 2.0 Mapper 327

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NES 2.0 mapper 327 is used for a 6-in-1 multicart. Its UNIF board name is BMC-10-24-C-A1.

Outer Bank Register ($6000-$7FFF, write)

Mask: $E000

A~FEDC BA98 7654 3210
  0110 .... ..CT POOO
              || |+++- Select 128 KiB PRG-ROM and CHR-ROM outer bank
              || +---- Select MMC3 inner PRG-ROM bank address mask
              ||        0: 128 KiB
              ||        1: 256 KiB
              |+------ Select CHR memory type
              |         0: CHR-ROM
              |         1: CHR-RAM
              +------- Select MMC3 inner CHR-ROM bank address mask
                        0: 128 KiB
                        1: 256 KiB

As it uses the MMC3 clones's WRAM interface, writing to the Outer Bank register requires enabling and not write-protecting WRAM in the MMC's $A001 register. Note that there are also 8 KiB of WRAM in the same address range. The outer bank register becomes locked against further writes once an outer bank other than 0 is selected, and is only unlocked on power-up.

MMC3-compatible registers

Mask: $E001

See MMC3.