NES 2.0 Mapper 529

NES 2.0 Mapper 529 denotes the YY0807, J-2148 and T-230 PCBs, used for particular bootlegs version of Datach Dragon Ball Z (T-230 PCB, with CHR-RAM) and Dragon Ball Z Gaiden (YY-0807 PCB, with CHR-ROM). It's a VRC4 clone (A2/A3, VRC4e) connected such that the $800x register has no effect, and the $A00x register selects a 16 KiB PRG-ROM bank, similar to the games' original Bandai mappers. Its UNIF board name is UNL-T-230.

Similarly to the Bandai mappers, it also supports saving data to serial EEPROM. The presence of EEPROM is denoted via the NES 2.0 header's PRG-NVRAM field indicating 256 byte of non-volatile save data. Unlike the original Bandai FCG boards that used an I²C interface, the bootleg variants use a 93C56 EEPROM via a Microwire interface, operated using the following registers:

Read Microwire Interface ($5000, read)

Mask: $F000

D~[.... ...D]
           +- Serial Data Output from the 93C56 EEPROM

Write Microwrite Interface ($8800, write)

Mask: $8800

D~[.... .ECD]
         ||+- Serial Data Input to 93C56 EEPROM
         |+-- Serial Clock to 93C56 EEPROM
         +--- Chip Select to 93C56 EEPROM

This register's address range overrides the VRC4's. The game writes to the $FFFx address range to operate this register.

The 93C56's EEPROM's org pin is tied to Vcc, indicating a 16-bit word length.