NES 2.0 Mapper 432

NES 2.0 Mapper 432 denotes the MMC3-based Realtec 8090 multicart circuit board.

• 3-in-1 High Standerd [sic] (DP-33)
• 160000000-in-1 (unknown cartridge code)

Solder Pad Enable Register ($6000-$7FFE, even)

Mask: $E001

D~7654 3210
  ---------
  .... ...S
          +- 1=Replace PRG-ROM with solder pad value
               in the CPU $8000-$FFFF address range

Outer Bank Register ($6001-$7FFF, odd)

Mask: $E001

D~7654 3210
  ---------
  ?NQP CmMb
   ||| |||+- PRG/CHR A17 if M=1
   ||| ||+-- PRG A17 mode
   ||| ||     0: from MMC3 (256 KiB inner bank)
   ||| ||     1: from b (128 KiB inner bank)
   ||| |+--- CHR A17 mode
   ||| |      0: from MMC3 (256 KiB inner bank)
   ||| |      1: from b (128 KiB inner bank)
   ||| +---- CHR A18
   ||+------ PRG A18
   |+------- PRG+CHR A19
   +-------- NROM-128 mode (1=enabled)

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. NROM-128 mode forces the MMC3 clone's CPU A14 input low, causing MMC3 register 6 to select both the bank at $8000 and $C000, and register 7 to select both the bank at $A000 and $E000.

MMC3-compatible registers ($8000-$FFFF)

Mask: $E001

See MMC3.