Have to take your word for it on the 800, that's a bit before my time. As for the Famicom, I was under the impression that the regular Famicom and the Famicom DD had separate games, or at least did before the Famicom DD got scrapped and those games got ported to the regular Famicom. Not sure, I'm not Japanese. Either way, this is all irrelevant with respect to the other systems I mentioned.
Also, the Famicom could play games on tape too? Never heard that. Did it work like the Starpath Supercharger?