Registers of the Power Architecture

Remember when Apple was moving away from PowerPC CPUs around 2005? Did you ever wonder where they went? They mostly went into game consoles. The Wii, Playstation 3, and Xbox 360 all have some variant of a PowerPC chip inside. PowerPC chips were never all that popular in personal computers outside of Apple. Presently, most are found in embedded and "big iron" form, like DVRs, cars, mainframes, and other big machines that banks and stuff use to have insane reliability.

Like x86, it's gone through many, not always backwards compatible revisions. I downloaded the current spec and fell over when it was a 1500+ page PDF! PowerPC means "Performance Optimization With Enhanced RISC Performance Computing". It is currently marketed under the name "Power".

All registers are 64-bit, unless otherwise noted. There are 32 integer registers, GPR0-GPR31, and 32 floating point registers, FPR0-FPR31, along with a Floating Point Status and Control Register (FPSCR). Branching is done with a Link Register, Count Register, Target Address Register, and a 32-bit Condition Register.

I started looking over the other kinds of registers, and almost keeled over. There are all kinds of registers dealing with debugging, exceptions, and almost duplicates of those for hypervisors. I give up!

I recall there being some NASA probe that was shipped with a PowerPC chip. All of the Apple enthusiasts were so happy.

Posted by Ryan Rampersad.

Curiosity and a few other recent space computers use the RAD750, a PowerPC variant. That's a change from the usual CPUs that were used for those things. Somehow, I thought that the older ones were MIPS-based.

Posted by the Andrew Bailey.

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