Just a minor point -- the Commander X16 isn't actually compatible with the Commodore 64 -- it's kind of like a fantasy version of what the Commodore 64 could have evolved into if they had stayed with that rather than shifting to the Amiga. It's "Kernal" compatible with the Commodore 64, Vic 20, and PET, meaning that developing for the platform should feel comfortable to programmers of those machines but it can't just run software for those machines unported.