INES Mapper 189

iNES Mapper 189 is used for unlicensed MMC3 games that bank PRG-ROM in 32 KiB amounts, like AxROM, BNROM and GNROM. Known games:

Thunder Warrior - 轰天至尊 from TXC Corporation with its variant Gluk the Thunder Warrior
Street Fighter II: The World Warrior from Yoko Soft and its many variants named Super Fighter II´, Master Fighter II, Master Fighter III, Mario Fighter III'

32 KiB PRG-ROM Bank Register

Original Board

D~[..PP ....] A~[010. ...1 .... ....] (Address & $E100)==$4100
     ++- PRG A16..15

The original board variants switch four 32 KiB PRG-ROM banks based on bits 4 and 5 on writes to CPU $4100-$5FFF (address bit 9 must be set).

Thunder Warrior - 轰天至尊: TXC 01-22017-000 60-pin PCB
Gluk the Thunder Warrior: TXC 01-22018-400 72-pin PCB
Street Fighter II: The World Warrior, Master Fighter II: The World Warrior, Super Fighter II´: FC-001EM (DIP)/FC-001EMC (COB) PCB

Thunder Warrior uses the 28-pin version of the PT8154 ASIC, which is a stripped-down MMC3 without any IRQ functionality; Street Fighter II: The World Warrior however needs a fully functional MMC3 clone, as the IRQ feature is utilized, and use a combination of a 40-pin PT8154 and another 40-pin PT8159.

Oversize Board

D~[.PPP ....] A~[01.. ...1 .... ....] (Address & $C100)==$4100
    +++- PRG A17..15

The oversize board (PCB name 自動車床控制板 MACP 811023) was only used for the hack Mario Fighter III, which increases the PRG-ROM size to 256 KiB, and so needs an additional bank bit. Although the address mask was broadened, so that the register now responds to writes to CPU $4100-$7FFF (address bit 9 must be set), the actual game still writes to the original $4132 address.

Generic Pirate Boards

A-37/810809-C

D~[..PP ....] A~[011. .... .... ....] (Address & $E000)==$6000, MMC3's $A001 bit 7 set
     ++- PRG A16..15

K-3086/810836-C

D~[.... ....] A~[011. .... .... ..PP] (Address & $E000)==$6000, MMC3's $A001 bit 7 set
                                  ++- PRG A16..15

There are countless pirated variants of the (already unauthorized) Street Fighter II 8-bit backport. Most of them connect the PRG-ROM Bank Register to the MMC3’s PRG-RAM interface, which simplifies address decoding. However, doing so requires modifying the PRG-ROM content to change the write address, and to enable the PRG-RAM interface by writing $80 to the MMC3’s $A001 register. Some of these respond to data bits 4 and bits 5, just like the original PCB; others respond to address bits 0 and 1, instead.

Generalized definition for emulation

To run all board variants without having to distinguish them, the long-standing practice in emulators has been to respond to all writes to $4020-$7FFF, perform a bitwise OR of the upper and lower nibble of the data byte being written, and use the result as the 32 KiB PRG-ROM bank number. This works even for the K-3086 board variant since it writes the bank number both in A0/A1 and D0/D1. To discard the generic pirate boards and only run the original and oversized board variants, respond to writes to $4100-$5FFF with address bit 9 set, and only use the upper nibble of the data byte being written.