NES 2.0 Mapper 344: Difference between revisions

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m (→‎Outer Bank and Mode Register ($6000-$7FFF, write): Showing address bits 0-3 in the mask.)
 
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[[Category:Multicart mappers]][[Category:MMC3-like mappers]][[Category:Mappers with scanline IRQs]]
{{DEFAULTSORT:344}}[[Category:Multicart mappers]][[Category:MMC3-like mappers]][[Category:Mappers with scanline IRQs]]
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'''.
'''NES 2.0 Mapper 344''' denotes the '''GN-26''' [[MMC3]]-based multicart circuit board. Its UNIF board name is '''BMC-GN-26''' (with incorrect PRG bank order).
 
* ''快打金卡终极挑战 (Kuàidǎ Jīnkǎ Zhōngjí Tiǎozhàn) 3/6-in-1''


==Outer Bank and Mode Register ($6000-$7FFF, write)==
==Outer Bank and Mode Register ($6000-$7FFF, write)==
  Mask: $E000
  Mask: $E00F
   
   
  A~FEDC BA98 7654 3210
  A~FEDC BA98 7654 3210
   -------------------
   -------------------
   .... .... .... DMCC
   011. .... .... SMBA
                   ||++- Select PRG and CHR base offsets
                   ||++- PRG/CHR A18..17
                   ||     0: PRG: $00000, CHR: $00000 (Menu)
                   ||+-- CHR A17 mode
                   ||    1: Invalid
                   ||    0: CHR A17=MMC3 A17
                  ||    2: PRG: $20000, CHR: $40000 (Street Fighter IV)
                   ||    1: CHR A17=$6000.0
                   ||    3: PRG: $40000, CHR: $60000 (Guevara)
                   |+--- Select PRG-ROM mode
                   |+--- Select PRG-ROM mode
                   |      0: Normal MMC3 mode
                   |      0: MMC3 PRG mode
                   |      1: MMC3 bank register 6 selects 32 KiB
                   |      1: NROM PRG mode
                  |        PRG-ROM bank at CPU $8000-$FFFF
                   +---- Solder pad test
                   +---- 1=CPU $8000-$FFFF becomes open bus if jumper
* WRAM must be enabled in $A001.7 before writing to this register.
                          not set (chooses between 3-in-1/6-in-1 menu)
* The inner PRG bank is restricted to 128 KiB.
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 mode PRG forces MMC3's CPU A13 and A14 inputs to GND and replaces MMC3's PRG A13 output with CPU A13. This means that MMC3 bank register 6 bits 1-3 provide PRG A14..A16 for the entire CPU $8000-$FFFF range.
* The common dump of ''快打金卡终极挑战 (Kuàidǎ Jīnkǎ Zhōngjí Tiǎozhàn) 3/6-in-1'' has the 128 KiB PRG-ROM banks mixed-up, correct would be in the order 0, 3, 1, 2.
* Depending on whether a solder pad is connected, setting the S bit may disable PRG-ROM. The menu sets this bit to select between two different game counts.


==MMC3-compatible registers==
==MMC3-compatible registers==
Mask: $E001
Mask: $E001
 
See [[MMC3]].
See [[MMC3]].
==Notes==
* 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.

Latest revision as of 21:01, 1 March 2022

NES 2.0 Mapper 344 denotes the GN-26 MMC3-based multicart circuit board. Its UNIF board name is BMC-GN-26 (with incorrect PRG bank order).

  • 快打金卡终极挑战 (Kuàidǎ Jīnkǎ Zhōngjí Tiǎozhàn) 3/6-in-1

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

Mask: $E00F

A~FEDC BA98 7654 3210
  -------------------
  011. .... .... SMBA
                 ||++- PRG/CHR A18..17
                 ||+-- CHR A17 mode
                 ||     0: CHR A17=MMC3 A17
                 ||     1: CHR A17=$6000.0
                 |+--- Select PRG-ROM mode
                 |      0: MMC3 PRG mode
                 |      1: NROM PRG mode
                 +---- Solder pad test
  • WRAM must be enabled in $A001.7 before writing to this register.
  • The inner PRG bank is restricted to 128 KiB.
  • NROM mode PRG forces MMC3's CPU A13 and A14 inputs to GND and replaces MMC3's PRG A13 output with CPU A13. This means that MMC3 bank register 6 bits 1-3 provide PRG A14..A16 for the entire CPU $8000-$FFFF range.
  • The common dump of 快打金卡终极挑战 (Kuàidǎ Jīnkǎ Zhōngjí Tiǎozhàn) 3/6-in-1 has the 128 KiB PRG-ROM banks mixed-up, correct would be in the order 0, 3, 1, 2.
  • Depending on whether a solder pad is connected, setting the S bit may disable PRG-ROM. The menu sets this bit to select between two different game counts.

MMC3-compatible registers

Mask: $E001

See MMC3.

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