Which OS still uses RISC (Reduced Instruction Set Computing) and which uses CISC(Complex Instruction Set Computing) Architecture? Can any one tell me which OS uses which instruction set?

1 Answer 1


It's not the OS that uses RISC or CISC, it's the processor.

x86 and x64 are CISC so any OS that runs on them is using a CISC instruction set.

ARM, MIPS, Atmel AVR, PIC, most everything else that is intended for low-power and mobile devices, and IBM's POWER machines are RISC CPUs.

Many OSs, including Windows and various *nix flavors, have been ported to both RISC and CISC processors.

  • Windows (Windows 10 IOT) and (Windows RT) and (Windows Phone 7,8, and 10) run on RISC hardware also.
    – Ramhound
    Jan 6, 2016 at 1:17
  • Yes, which is why I said Windows has been ported to both RISC and CISC. In the past there have been other RISC ports of Windows NT: MIPS R4000, Alpha, and Power PC. Jan 6, 2016 at 1:27
  • I missed that part. lets be honest nobody remembers Windows NT running on those platforms anymore except the few people that might have actually used it on those platforms.
    – Ramhound
    Jan 6, 2016 at 1:32
  • It's a proud and lonely thing to be an Alpha fan. :D Jan 6, 2016 at 1:38
  • Though, modern X86es are Riscy though their instruction set it CISC. much much much too broad
    – Journeyman Geek
    Jan 6, 2016 at 1:40

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