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I'd love to see a detailed write-up on how an ISA is protected. I've never really understood what protects the x86 instruction set. I'd always assumed there wer

• Taniwha 10y ago
  Intel's ISA is protected by fear of its army of lawyers, something from which no small company could (financially) survive a head on attack. I worked on an x86 clone 20 years back, we analysed Intel's patents in depth to make sure we were safe, the biug one for us was Intel's segmentation/MMU patent - they essentially had patented segmentation followed by (unrelated) mmu processing - there was obvious prior art (cough 360, cough) but that's a bit of crap shoot, I came up with a brilliant way around this, only to discover a patent from someone else in the process of doing an x86 clone (Exponential I think). In the end we conflated our segmentation hardware and our TLBs effectively bypassing the core of Intel's patent You can't patent a list of instructions, you can copyright a bunch of mnemnomics
  • new299 10y ago
    That's really interesting thanks! I wonder if the army of lawyers protection also holds for ARM. Or perhaps there licenses are cheap enough that people don't care.