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).
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
Mask: $E001
See MMC3.
Categories: Mappers with scanline IRQs, MMC3-like mappers, Multicart mappers