The VAX 9000 does branch prediction & speculative fetches; kills,
aborts, and register logs made for debugging fun. "A cache cycle wasted
is lost forever" met "waste not, want not". It fetches aggressively.
It has multiple microcodes - some loadable, other compiled (and
optimized) into gates.
Paul - be careful. All CPU's post the IBM AGS that used branch prediction
are suspect. Russ Robelen (who was the 360/50 lead, worked on 360/90 and
lead AGS) has the speculative executing patent. I tweaked him when it all
came out and said - look at what you did.
What Russ and team are great
"Spectre" is one of two notorious bugs of modern CPUs involving speculative
execution. I rather doubt that VAX is affected by this but I suspect others
here have a lot more knowledge.
paul
> Begin forwarded message:
>
> From: co...@sdf.org
> Subject: VAX + Spectre
> Date: September
