I didn't know if this was the right forum for this, if not, please feel free to move it.

I've seen roms of multiple Famicom games that are for the TurboGrafx. How was this done? I could be missing something really obvious, but I don't see how this would be possible. If you provide an explanation, feel free to be as technical as you want, I'll probably be able to decipher it.

*if this has been asked before, I apologize. I did use the search feature, though it's possible I merely entered the wrong search terms.