NES 2.0 Mapper 446

NES 2.0 Mapper 446 denotes Mindkids’ SMD172B_FPGA circuit board. It is used for some large multicarts from Pixel Games, as well as licensed rereleases from Retro-Bit and a handful of homebrew games:

Jay and Silent Bob: Mall Brawl
Blazing Rangers / 炎のRangerman
Hammerin’ Harry 2: Dan the Red Strikes Back / Daiku no Gen San 2 (Retro-Bit rerelease)

Supervisor Registers

Mapper Selection ($5000, write)

D~[L..M MMMM]
   |  +-++++-- Mapper for the FPGA to emulate
   +---------- 1=Lock supervisor registers until reset

The set of mappers that the FPGA can emulate differs across cartridges and is selected by the NES 2.0 Submapper.

NES 2.0 Submapper	$5000.0-4	Mapper
0	01	SKROM
1	00	UNROM
1	01	TKROM
1	02	BNROM
1	03	CNROM
1	04	ANROM
1	05	SKROM
1	06	SNROM
1	07	SUROM
1	08	GNROM
1	09	PNROM
1	0A	HKROM
1	0B	INES Mapper 152
1	0E	TKSROM
1	0F	INES Mapper 189
1	10	INES Mapper 026
1	12	INES Mapper 022
1	15	INES Mapper 025
1	18	INES Mapper 023
1	1A	VRC1
2	00	UNROM
2	01	TKROM
2	02	BNROM
2	03	CNROM
2	04	ANROM
2	05	SKROM
2	06	SNROM
2	07	SUROM
2	08	GNROM
2	09	TLROM
2	0A	HKROM
2	0B	INES Mapper 152
2	0D	TKROM
2	0E	TKSROM
2	0F	INES Mapper 189
2	10	INES Mapper 026
2	12	INES Mapper 022
2	15	INES Mapper 025
2	18	INES Mapper 023
2	1A	VRC1
3	01	H3001

Outer 8 KiB PRG-ROM Bank LSB ($5001, write)

D~[BBBB BBBB]
   ++++-++++- PRG A20..A13

Outer 8 KiB PRG-ROM Bank MSB ($5002, write)

D~[BBBB BBBB]
   ++++-++++- PRG A28..A21

Inner 8 KiB PRG-ROM Bank Mask ($5003, write)

D~[MMMM MMMM]
   ++++-++++- PRG A20..A13 mask

The register has an inverted meaning in Submapper 2 vs. Submappers 0-1. In Submappers 0-1, an “1” bit means that the Outer Bank bit is used. In Submapper 2, an “1” bit means that the Inner Bank bit is used.

Flags ($5004, write)

D~[..CC ...M]
     ||    +- Mirroring (V=1)
     ++------ Inner CHR-RAM address mask
              0x: 256 KiB
              10: 128 KiB
              11: 32 KiB

The mirroring bit has no effect when selecting an FPGA mapper with software-selectable mirroring.

CHR RAM protect ($5005, write)

D~[.... .P..]
         +- 1: Write-protect CHR-RAM

Outer 8 KiB CHR-RAM Bank ($5006, write)

D~[...B BBBB]
      +-++++- CHR A17..A13

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