FxROM

The generic designation FxROM refers to cartridge boards made by Nintendo that use the Nintendo MMC4 mapper.

The following FxROM boards are known to exist:

Board	PRG ROM	PRG RAM	CHR
FJROM	128, 256 KB	8 KB	16, 32, 64 KB ROM
FKROM	128, 256 KB	8 KB	128 KB ROM

Overview

• PRG ROM size: up to 256 KB
• PRG ROM bank size: 16 KB
• PRG RAM: 8 KB plus optional battery
• CHR capacity: up to 128 KB ROM
• CHR bank size: 4 KB
• Nametable mirroring: Controlled by mapper
• Subject to bus conflicts: No

Hardware

These are the only Nintendo boards to use a specific chip dedicated to safe battery backup.

See also

• Nintendo MMC4