Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.arch
Subject: Re: 80386 vs. 68030
Message-ID: <5436@cbmvax.UUCP>
Date: 5 Dec 88 20:32:19 GMT
References: <788@stolaf.UUCP>
Distribution: na
Organization: Commodore Technology, West Chester, PA
Lines: 31

in article <788@stolaf.UUCP>, mike@stolaf.UUCP (Mike Haertel) says:
> Keywords: 680x0 wins

> In article <5375@cbmvax.UUCP> daveh@cbmvax.UUCP (Dave Haynie) writes:
>>Going all out, I'd expect a 68020 to be slower than an 80386 system, a
>>68030 to be faster.

> I disagree.  Working for the GNU project this summer I had an opportunity
> to use various 386 and '020 machines and, taking differences of clock
> speed, etc. into account I had the impression that the '020 machines
> were faster.  

One thing I wasn't think of is that many of the existing workstation level
'020 machines have a faster MMU.  Motorola's 68851 is nice from an MMU
function point of view; it can do practically anything you can think of.
But it always adds a wait state to a 68020 memory access.  Perhaps some
of the Sun MMUs deliver performance closer to that of the raw 68020.

Of course, the other factor may be how well each architecture is matched to
the OS it's running with.  I based my guess above mainly on apparent hardware
efficiencies.  I've seen articles that put the '386 ahead of the '020, and
others that switch that around.   No matter what, it looks to be a pretty
close call, and it's probably application dependent when it comes right down
to it.

> Mike Haertel					mike@wheaties.ai.mit.edu
> 			In Hell they run VMS.
-- 
Dave Haynie  "The 32 Bit Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
              Amiga -- It's not just a job, it's an obsession