I just got a Famicom RAM cart adapter in the mail yesterday, but it was loose and by itself. Just wondering, but what's the EXP port on the back for? Is there an actual wire that plugs into that? If so, do they sell them, or would I need to get a custom wire made?
It's not used by any known hardware. The engineers often make expansion ports when they design hardware just in case they want to make more hardware that's compatible with it in the future (CD drive units and so on). But they often remains unused.
afair it's just 7 bit GPIO (or 6 bit)