NES 2.0 Mapper 366

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NES 2.0 Mapper 366 is used for an MMC3-based multicart PCB (GN-45):

  • 4-in-1 (K-3131GS)
  • 4-in-1 (K-3131SS)

Outer Bank Register ($6800)

Mask: unknown, probably $E0F0

A~FEDC BA98 7654 3210
  0110 1000 LOOO ....
            |+++------ Select outer 128 KiB PRG-ROM and CHR-ROM bank
            +--------- 1=Lock outer bank

This register is accessible regardless of whether WRAM is enabled in the MMC3 clone's A001 register. It overlays the 8 KiB of WRAM that both multicarts have, making the Lock bit necessary to prevent the outer bank from changing once the game writes to WRAM.

MMC3-compatible registers

Mask: $E001

See MMC3.


FCEUX emulates this PCB under mapper number 205 together with "OK-411" (NES 2.0 Mapper 361), both of which are in turn different from the iNES Mapper 205 described in that mapper's wiki article.

See also

NES 2.0 Mapper 361 describes a simpler variant that latches the data bus instead of the address bus.