NES 2.0 Mapper 344: Difference between revisions

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(Correction, no longer guided by ROM file with misordered banks.)
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  A~FEDC BA98 7654 3210
  A~FEDC BA98 7654 3210
   -------------------
   -------------------
   .... .... .... DMCC
   .... .... ..oo DSOO
                  ||++- Select PRG and CHR base offsets
              || ||++- PRG/CHR A17..A18 when S=0
                  ||    0: PRG: $00000, CHR: $00000 (Menu/Street Fighter IV)
              || |+--- Select PRG-ROM mode
                  ||    1: Invalid
              || |      0: Normal MMC3 mode
                  ||    2: PRG: $20000, CHR: $40000 (Contra Force)
              || |      1: Pseudo-NROM: MMC3 bank register 6 bits 1-3
                  ||     3: PRG: $40000, CHR: $60000 (Guevara)
              || |        provides PRG A14..A16 for CPU $8000-$FFFF
                  |+--- Select PRG-ROM mode
              || +---- PRG A14 mode when S=1
                  |      0: Normal MMC3 mode
              ||        0: PRG A14=CPU A14 (NROM-256)
                  |      1: MMC3 bank register 6 selects 32 KiB
              ||        1: PRG A14=MMC3 bank register 6 bit 1
                  |        PRG-ROM bank at CPU $8000-$FFFF
              ++------ PRG/CHR A17..A18 when S=1
                  +---- 1=CPU $8000-$FFFF becomes open bus if jumper
                          not set (chooses between 3-in-1/6-in-1 menu)
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.
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.


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==Notes==
==Notes==
* The inner PRG-ROM bank is restricted to 128 KiB, the CHR-ROM bank unrestricted.
* The inner PRG-ROM bank is restricted to 128 KiB, the CHR-ROM bank unrestricted.
* This description is based on testing with Nestopia Plus!, which ignores the written data.

Revision as of 21:08, 6 December 2019

NES 2.0 Mapper 344 is used for the Kuai Da Jin Ka Zhong Ji Tiao Zhan 3-in-1 (3-in-1,6-in-1,Unl) multicart. Its UNIF board name is BMC-GN-26.

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

Mask: $E000

A~FEDC BA98 7654 3210
  -------------------
  .... .... ..oo DSOO
              || ||++- PRG/CHR A17..A18 when S=0
              || |+--- Select PRG-ROM mode
              || |      0: Normal MMC3 mode
              || |      1: Pseudo-NROM: MMC3 bank register 6 bits 1-3
              || |         provides PRG A14..A16 for CPU $8000-$FFFF
              || +---- PRG A14 mode when S=1
              ||        0: PRG A14=CPU A14 (NROM-256)
              ||        1: PRG A14=MMC3 bank register 6 bit 1
              ++------ PRG/CHR A17..A18 when S=1

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.

Notes

  • The inner PRG-ROM bank is restricted to 128 KiB, the CHR-ROM bank unrestricted.
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