Author has clearly not heard about NexGen! They implemented a RISC architecture that code morphed x86 i586 design. They were then bought out by AMD who shortly thereafter adopted the design for their own architecture. Then Intel had no choice but to adopt NexGen architecture as well lool. We all use NexGen Architecture now. The most famous microprocessor no one's heard of. I only know because NexGen was based in Milpitas and that's where I live, so Milpitas Architecture is like hometown pride.
As for patents, Xed is tiny (only ~4kb) and it allows us to distinguish the which instructions belong to which microarchitectures, e.g. k8, sse3, sse4, avx. That gives us a clear accurate picture of the intellectual property rolloff, thereby enabling a fabless chip or emulator to simply ignore the encumbered parts of the encoding space. The tradeoff is you can't patent troll Intel (due to Xed being licensed Apache 2.0) and I think that's fair.
Nexgen was great, the lack of a FPU at that moment in time however was fatal at launch.
Quake was just starting to ignite the world and pentium performance at 486 prices would have done more, but no fpu... it ran NT fine enough although my memory wants to say Microsoft detected it as a 386 so that would have cut NT 4 out of the picture.
I thought knowledge of them was more common but I guess not
The TL;DR seems to be that if you restrict yourself to implementing an ISA from 20 years ago, your chip can indeed be patent free, but that isn't going to run modern software - maybe not even modern x86 32-bit software!
