NES 2.0 Mapper 344

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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: $E000

A~FEDC BA98 7654 3210
  011. .... .... SMBA
                 ||++- PRG/CHR A18..17
                 |+--- Select PRG-ROM mode and CHR A17 mode
                 |      0: MMC3 PRG mode, CHR A17=$6000.0
                 |      1: NROM PRG mode, CHR A17=MMC3 A17
                 +---- 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.