Last month the secrets of the Nintendo Famicom to Nintendo Entertainment System adapter hidden inside early copies of Gyromite came to the light of day, and now VintageComputing.com takes a second look at the technology by performing a permanent conversion of a Famicom cartridge into a NES game pak. Using the adapter and some old fashioned patience it's possible to remove the ROM board from a Famicom cartridge and mate it with the adapter all within the comforting gray plastic shell of a traditional NES game pak.
You will also have to disassemble your Gyromite cartridge (the one with the converter board in it). They typically have five screws that require a small, flat-bladed screwdriver for unscrewage (that should be a word). After that, you’ll have to unscrew the two screws that hold the Gyromite ROM board and adapter assembly down on the face half of the cartridge. Then, unplug the Gyromite ROM board from the connector on the top assembly and set it aside, feed it to your dog, or play it in your Famicom — we won’t be needing it anymore.
The article outlines the conversion of Super Mario Bros. 3, but since that game was released for the NES it may be better to use those adapters to convert Famicom-exclusive titles. Wow your friends with the "NES" versions of Devil World or Mother, for instance. If you have friends that would be wowed by this sort of thing, that is.