Yes, and what few people know, is that x86 co-processors in general really only had to stick to the hardware interface given by Intel. What they actually did wi

Yes, and what few people know, is that x86 co-processors in general really only had to stick to the hardware interface given by Intel. What they actually did with that was up to the co-processor. Best known case in point were the Weitek math co-processors which were not actually machine code compatible with the Intel x87s.