> Surely you don't need anything from them to design a chip from scratch that implements the same instruction set, as Cyrix and AMD famously did to the ia32. C

> Surely you don't need anything from them to design a chip from scratch that implements the same instruction set, as Cyrix and AMD famously did to the ia32. Cyrix and AMD got (cross-)licenses from Intel: * https://www.sec.gov/Archives/edgar/data/2488/000119312509236705/dex102.htm https://www.sec.gov/Archives/edgar/data/2488/000119312509236... * https://www.kitguru.net/components/cpu/anton-shilov/amd-clarifies-cross-license-with-intel-change-of-control-terminates-agreement-for-both/ https://www.kitguru.net/components/cpu/anton-shilov/amd-clar... This has been true since the very beginning: > Early 1980s--IBM chooses Intel's so-called x86 chip architecture and the DOS software operating system built by Microsoft. To avoid overdependence on Intel as its sole source of chips, IBM demands that Intel finds it a second supplier. * https://www.cnet.com/tech/tech-industry/intel-and-amd-a-long-history-in-court/ https://www.cnet.com/tech/tech-industry/intel-and-amd-a-long... * https://jolt.law.harvard.edu/digest/intel-and-the-x86-architecture-a-legal-perspective https://jolt.law.harvard.edu/digest/intel-and-the-x86-archit... The reverse engineering happened with Compaq doing the BIOS: * https://www.allaboutcircuits.com/news/how-compaqs-clone-computers-skirted-ibms-patents-and-gave-rise-to-eisa/ https://www.allaboutcircuits.com/news/how-compaqs-clone-comp... This was a major plot point in AMC's (very good) show Halt and Catch Fire: * https://www.internethistorypodcast.com/2014/05/the-incredible-true-story-behind-amcs-halt-and-catch-fire-how-compaq-cloned-ibm-and-created-an-empire/ https://www.internethistorypodcast.com/2014/05/the-incredibl... * https://arstechnica.com/gaming/2014/05/review-halt-and-catch-fire-reverse-engineers-pop-culture/ https://arstechnica.com/gaming/2014/05/review-halt-and-catch... * https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(TV_series) https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(TV_series...