NES 2.0 Mapper 345

NES 2.0 Mapper 345 is used for the New Star 6-in-1 Game Cartridge multicart. Unusually, it combines MMC3 and AxROM games. Its UNIF board name is BMC-L6IN1. CHR data comes from 8 KiB of MMC3-banked CHR-RAM.

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

Mask: $E000

D~7654 3210
  ---------
  OOMS mmPP
  |||| ||++- Select 32 KiB inner PRG-ROM bank in AxROM mode
  |||| ++--- Select PRG-ROM banking mode (0=AxROM, 1-3=MMC3)
  |||+------ Select 1 KiB CIRAM bank in one-screen mirroring mode
  ||+------- Select nametable mirroring type
  ||          0: from MMC3
  ||          1: one-screen mirroring
  ++-------- Select 128 KiB outer PRG-ROM bank in either mode

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.

MMC3-compatible registers

Mask: $E001

See MMC3.