NES 2.0 Mapper 392

NES 2.0 Mapper 392 denotes the 00202650 PCB, used on an 8-in-1 multicart. It uses an MMC3 clone with both CHR-ROM and CHR-RAM and an outer bank register that is implemented using a GAL16v8.

The circuit board mounts two PRG-ROM chips each holding 512 KiB of game data (U2/U3), a third PRG-ROM chip with 32 KiB of menu data (U1), as well as two 512 KiB CHR-ROM chips holding game graphics (U10/U4) and 8 KiB of CHR-RAM (U6). The NES 2.0 file holds these chips' data in the order U2-U3-U1-U10-U4.

Outer Bank Register ($6000-$7FFF, write)

Mask: $E000

D~7654 3210
  ---------
  ...M .BBB
     |  +++- PRG/CHR A19..A17 in game mode
     +------ 0: Menu Mode
             1: Game Mode, lock register

Notes

• In menu mode, the 32 KiB PRG-ROM chip is mapped into CPU address space, and 8 KiB of unbanked CHR-RAM is mapped into PPU address space.
• In game mode, the 1 MiB PRG-ROM and 1 MiB CHR-ROM chips are mapped and banked by the MMC3 clone within the 128 KiB PRG/CHR window selected by the outer bank register.
• The outer bank register functions independently of the MMC3's WRAM register.
• See also: NesDev forum post with krzysiobal's analysis