NES 2.0 Mapper 366
NES 2.0 Mapper 366 is used for an MMC3-based multicart PCB (GN-45):
- 4-in-1 (K-3131GS)
- 4-in-1 (K-3131SS)
Mask: unknown, probably $E0F0
A~FEDC BA98 7654 3210
-------------------
0110 1000 LOOO ....
|+++------ Select outer 128 KiB PRG-ROM and CHR-ROM bank
+--------- 1=Lock outer bank
This register is accessible regardless of whether WRAM is enabled in the MMC3 clone’s A001 register. It overlays the 8 KiB of WRAM that both multicarts have, making the Lock bit necessary to prevent the outer bank from changing once the game writes to WRAM.
Mask: $E001
See MMC3.
FCEUX emulates this PCB under mapper number 205 together with “OK-411” (NES 2.0 Mapper 361), both of which are in turn different from the iNES Mapper 205 described in that mapper’s wiki article.
NES 2.0 Mapper 361 describes a simpler variant that latches the data bus instead of the address bus.