To be clear, you're talking about the original POWER ISA. The PowerPC ISA has subsequently been renamed the Power ISA (not to be confused with the POWER ISA). Confusingly, IBM's POWER CPUs (POWER3, POWER4, POWER5, POWER6, POWER7, POWER8, POWER9) since POWER3 implement the Power ISA (then known as the PowerPC ISA), not the POWER ISA. POWER2 was the last CPU to implement the POWER ISA.

https://en.wikipedia.org/wiki/IBM_POWER_instruction_set_arch...

https://en.wikipedia.org/wiki/Power_ISA