iNES Mapper 159 is used for Bandai FCG boards with an LZ93D50 ASIC and a 128-byte serial EEPROM (X24C01). The 128 bytes must be denoted as PRG-NVRAM in the NES 2.0 header using byte value $10.
All registers function the same way as INES Mapper 016, submapper 5, except that the serial EEPROM is not a 24C02 but Xicor's X24C01. This EEPROM has operational differences compared to both the larger 24C02 and other vendors' 24C01. Bandai's developers consistently thought the X24C01 was a little-endian device, and their code clocks in address and data bytes assuming this. However, it's actually a big-endian device, and a multi-byte read or write from EEPROM will increment the address accordingly.
Categories: INES Mappers, Mappers with cycle IRQs