What ever happened to Tandem and NonStop OS 2039

Kelli Halliburton

WHOA there... Pentium Pro *DID NOT* have MMX at all. MMX was a quick graft onto the late rev Pentium (aka "586") cores, too late for it to be included in the Pro. However the II did get MMX anyway, but I'm not sure that it actually bested the normal P6 FP performance anyway (which was good enough to worry the RISC vendors - see the comp.arch threads of the time).

Naw, PII was a refinement of the Pro that made it cheaper and quicker on legacy ("34586") code. The original Pentium Pro was an MCM, one chip had the core, the other had the cache running at 100% of core speed, all in one package. The Pentium II reduced cost by moving the cache out of the package and on to discrete components on a circuit board - hence the Slot format. The downside of that was that the cache was clocked at 50% of the core speed - which hurt some codes (I found that a PPro-200 was able to blitz a PII-300 on some codes !).

Didn't the II introduce SSE, or was that the III ?

AKA "NetBurst" or "NetBust" if you are working on branchy code.

Good summary. :)

Happy to oblige, I'll wait for the corrections to my corrections with interest. :P

Cheers, Rupert