Famicom Expansion Port Switcher Mod

The expansion ports on the Japanese Famicom consoles have a problem - some western games are incompatible with the controllers connected to this port, due to the fact that this expansion port did not exist on the NES, and therefore was ignored by some devs.

Significant Titles Affected:

• Arkanoid II
• Battletoads
• Dragon's Lair
• Paperboy
• Pinball
• RoboCop 2/3
• Star Force
• Super Mario Bros. USA
• Snake Rattle'n'Roll
• Terminator 1/2
• Tetris (Tengen)
• Zelda II - The Adventure of Link

I created the FamiCoun and the TwinDiamond a few years ago and both suffered from this programming oversight by these devs. So it is only natural for me to take matters into my own hands to fix it.

This switcher mod will enable you to switch the role of the expansion controllers between internal and external. It requires experience in console modding and might not be friendly for everybody. Please keep this in your mind before attempting.

Details are provided in the Project Wiki, separated by console models and motherboard revisions.

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Special Thanks

Voultar (for insisting on a proper logic circuit implementation)

• Twitter

Redherring32 (for providing the board scan of Famicom GPM for reference)

• Twitter

Zoggins (for spotting the problematic Twin Famicom motherboard rev)

• Twitter

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Shield:

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.