NES 2.0 Mapper 344

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
                 ||+-- 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.