There's been quite a few to do hybrid architectures with one article suggesting AMD might do x86 + ARM: https://www.extremetech.com/computing/182790-amds-next-

There's been quite a few to do hybrid architectures with one article suggesting AMD might do x86 + ARM: https://www.extremetech.com/computing/182790-amds-next-big-gamble-arm-and-x86-cores-working-side-by-side-on-the-same-chip https://www.extremetech.com/computing/182790-amds-next-big-g... It was also done the other way around with RISC workstations like Sun's running UNIX on SPARC coming with x86 cards to run their apps. I never checked it out to see what it was like but it was an advertised feature of SunBlade workstations. Additionally, IBM made PCI cards that could run their mainframe code on regular systems. https://en.wikipedia.org/wiki/SunPCi https://en.wikipedia.org/wiki/SunPCi https://en.wikipedia.org/wiki/PC-based_IBM-compatible_mainframes https://en.wikipedia.org/wiki/PC-based_IBM-compatible_mainfr...