Funny thing, you could make a constant length superset of x86-64 with backwards compatibility, and it's even going to run fast... (The instruction decoder woul

Funny thing, you could make a constant length superset of x86-64 with backwards compatibility, and it's even going to run fast... (The instruction decoder would become more of a translator.) The bigger problem with x86 is the implicit hard synchronization barrier after most writes. This cannot be easily fixed without introducing new instructions altogether.