NES 2.0 Mapper 334

NES 2.0 mapper 334 is used for the 5/20-in-1 1993 Copyright multicart.

PRG-ROM Bank Register ($6000, write)

Mask: probably $6003

D~7654 3210
  ---------
  .... .PP.
        ++- Select 32 KiB PRG-ROM bank at CPU $8000-$FFFF

Unknown Register ($6001, write)

Mask: probably $6003

Unknown meaning; the menu writes $01 to it.

Jumper Register ($6002, read)

Mask: probably $6003

D~7654 3210
  ---------
  OOOO OOOJ
  |||| |||+- Jumper setting
  |||| |||    0: Show 20-in-1 menu (i.e. with repeats)
  |||| |||    1: Show 5-in-1 menu (i.e. without repeats)
  ++++-+++-- Open bus

The “hardware test” menu (seen when pressing SELECT+A+B during the menu) expects the jumper at zero.

MMC3-compatible registers

Mask: $E001

See MMC3.

Notes

The MMC3 clone is only used for Mirroring and CHR-ROM banking; the PRG-ROM bank comes entirely from an additional register. As they use the MMC3 clones’s WRAM interface, accessing the $600x registers requires enabling and not write-protecting WRAM in the MMC’s $A001 register.

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