biggest problem here is that the nes can be very easily cloned as it was mostly off the shelf or slightly modified parts i believe the turbografx and duo had a decent ammount of custom hardware inside considering they were made by nec who had the resources sitting around to design and build custom hardware. Thus the reason it was initially so scary for nintendo, and even more so for sega. Luckily for them nec didn't seem to understand that software sells the system and that packaging in a crappy pack-in would hurt them so badly.