3 ms·
POWER inherited a lot of baggage from the IBM R/T, the first real go at RISC, so it was the most un-RISC-like of the RISC ISA's. That was the included all the a
by cbsmith 11y ago
POWER inherited a lot of baggage from the IBM R/T, the first real go at RISC, so it was the most un-RISC-like of the RISC ISA's. That was the included all the addressing modes and a surprisingly rich ISA. Those were all considered no-no's for unlocking the advantages of RISC.
- protomyth 11y agoThanks. Is there a document / blog post that tells exactly what the baggage and addressing modes were? I've heard the problem but never found the actual specifics.
- cbsmith 11y agoWell, a fairly handy reference might be the PowerPC 601 ISA docs: http://www.freescale.com/files/32bit/doc/user_guide/MPC601UM.pdf http://www.freescale.com/files/32bit/doc/user_guide/MPC601UM... Chapter 3 touches on memory addressing modes. The 601 was more compatible with the full POWER ISA that came before it, but looking at the docs for the POWER ISA itself would probably be more instructive.