Path: utzoo!mnetor!uunet!ncc!alberta!access!edm!rroot
From: rroot@edm.UUCP (uucp)
Newsgroups: comp.arch
Subject: Re: Intel 80960, Memory Mgmt, and Military parts
Message-ID: <266@edm.UUCP>
Date: 20 Apr 88 06:07:42 GMT
References: <3383@omepd>
Organization: Unexsys Systems, Edmonton,AB.
Lines: 28

From article <3383@omepd>, by mcg@omepd (Steven McGeady):
> 
> In article <949@ima.ISC.COM> johnl@ima.UUCP (John R. Levine) writes:
> I failed to mention that the 80960MC also supports some underlying support
> for tasking (process) control.  This is decidely non-RISCy, I know, but
> the 80960 is not an ideological processor, it is a pragmatic one.  The
 Oh god, not again!. I hope that the 80960 does a better job of task 
switching than the 80286 did. I'm starting to SERIOUSLY doubt the utility
of hardware assist in areas like this given the following examples:
  1: the 8086's string manipulation instructions.. said to give it such a
big advantage over the 68000.  If you do cycle counts, though, it turns out
that a 68000 move/dbcc loop is faster than the intel equivalent.
  2: 80286 task switching: touted as such a great advancement, but from all
I've heard, task switching on the '286 seems to be "phenomenally slow".
  3: On an amdahl V8, the mvcl (move character long), which allowed string 
moves up to memory size (then 16MEG) in one instruction, was actually
SLOWER than coding a loop with the more limited MVC (256 bytes max)
instruction. 
  The person who (did and) told me about the benchmarks alluded to the
fact that MVCL was even worse on some of the older machines.

  In summary: don't add a whole stack of 'useful' instructions if it 
just slows things down. (I think I'm starting to sound like a RISCer).
-- 
-------------
 Stephen Samuel 
  {ihnp4,ubc-vision,vax135}!alberta!edm!steve
  or userzxcv@uqv-mts.bitnet