Re: OoO execution (was: The Seymour Cray Era of Supercomputers)

John Levine <johnl@taugh.com> writes:

The 360/91 had primitive branch prediction in "loop mode".  It had an
eight doublewprd instruction queue (which it confusingly called a stack.)
If a program did a backward branch of less than eight doublewords, it'd
stop prefetching and execute out of the queue until the program fell or
branched out.

The 68010 had a similar feature (with a smaller buffer), but I don't
think one would call it branch prediction.  In any case, I meant
speculative execution based on branch prediction (but did not write it
that way), and the 360/91 did not do speculative execution AFAIK.

- anton
--
'Anyone trying for "industrial quality" ISA should avoid undefined behavior.'
  Mitch Alsup, <c17fcd89-f024-40e7-a594-88a85ac10d20o@googlegroups.com>