Path: utzoo!attcan!uunet!cbmvax!daveh
From: daveh@cbmvax.UUCP (Dave Haynie)
Newsgroups: comp.sys.next
Subject: Re: Next and the competition
Message-ID: <5614@cbmvax.UUCP>
Date: 3 Jan 89 19:16:54 GMT
References: <2596@udccvax1.acs.udel.EDU>
Organization: Commodore Technology, West Chester, PA
Lines: 36

in article <2596@udccvax1.acs.udel.EDU>, anand@vax1.acs.udel.EDU (Anand Iyengar) says:

> I recall reading a report from Motorola which says that the 68030 can 
> perform 50% better than than the 68020 (2 cycles/mem-access vs. 3 for the 
> 68020).  

Ideally, yeah, and that's ignoring the data cache effects.  If you wanted that
'020 to run UNIX, you might add a 68851, which adds a wait state, so in more
practical terms, the '030 is probably better than 100% faster than an '020
at the same speed.  If you let it be.  The NeXT has slower system memory, and
so takes advantage of another '030 feature, burst fill of cache lines.  This
lets it eat 4 longwords in 9 cycles (according to the reports of the NeXT
I've read, at least), though writes are probably more like 3 or 4 clocks long.
In other systems I've found burst mode to increase system speed by about 20%
in practice (you don't always use all 4 longwords), but that depends on the
memory speed difference between burst and non-burst.  With similar memory
systems I'd expect an '030 system to very easily outrun a '386 system, 
especially running UNIX.  However, that may not be the real-world case -- there
are a number of high-performance '386 system, using external cache and faster
DRAM, that may give NeXT a run for the money, at least in terms of CPU 
performance.  Since many of these are based around the otherwise primitive
PC-AT architecture, I'd bet that a suitably equipped NeXT would still come
out far ahead in I/O performance, though under UNIX, you might not get to
see the difference very often.

> Mac OS still doesn't have multitasking -- which the Amiga does (and has for 
> quite a while  I'm still waiting to see what Commodore makes of the 2500.  
> Could be interesting).

Glad you think so!  

> 							Anand Iyengar.  
-- 
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