NES 2.0 Mapper 556

NES 2.0 Mapper 556 is used for the for the 超强小新2+瑪莉家族 7-in-1 (JY-215) multicart and an unknown 50-in-1 MMC3+VRC4+NROM multicart, which has VRC4 compatibility to support Crayon Shin-Chan (hack of Bio Miracle Bokutte Upa) and Goal 2 (VRC4 hack of JPN version).

The multicart’s game select register functions similar to iNES Mapper 045, but is moved to $5000 and repurposed a bit in the second write to select MMC3/VRC4 mode. The VRC4 mode seems to behave like the VRC4e variant (A2/A3 connected to VRC4 A0/A1).

CHR-OR LSB ($5000 #0, write)

Mask: Unknown

D~7654 3210
  ---------
  CCCC CCCC
  ++++-++++- Select CHR A10-A17

PRG-OR LSB ($5000 #1, write)

Mask: Unknown

D~7654 3210
  ---------
  pPPP PPPP
  |+++-++++- Select PRG A13-A19
  +--------- Select PRG A20, CHR A20

CHR-AND, CHR-OR/PRG-OR MSB ($5000 #2, write)

Mask: Unknown

D~7654 3210
  ---------
  MPCC cccc
  |||| ++++- Select number of CHR bits from MMC3
  ||||       ($F: 256 KiB, $E: 128 KiB ... $7-$0: 1 KiB)
  ||++------ Select CHR A18-A19
  |+-------- Select PRG A21, CHR A21
  +--------- ASIC compatibility mode
             (0=MMC3, 1=VRC4)

PRG-AND, register lock ($5000 #3, write)

Mask: Unknown

D~7654 3210
  ---------
  L-PP PPPP
  | ++ ++++- Select PRG-AND mask (inverted)
  |          ($00: 512 KiB, $20: 256 KiB...)
  +--------- 1=Lock outer bank registers

NES 2.0 Mapper 556

CHR-OR LSB ($5000 #0, write)

PRG-OR LSB ($5000 #1, write)

CHR-AND, CHR-OR/PRG-OR MSB ($5000 #2, write)

PRG-AND, register lock ($5000 #3, write)

See Also