Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!rutgers!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga competitiveness
Message-ID: <14822@cbmvax.commodore.com>
Date: 2 Oct 90 22:47:23 GMT
References: <90271.190320UH2@psuvm.psu.edu> <420@caslon.cs.arizona.edu> <1091@ucsvc.ucs.unimelb.edu.au>
Reply-To: daveh@cbmvax.commodore.com (Dave Haynie)
Organization: Commodore, West Chester, PA
Lines: 31

In article <1091@ucsvc.ucs.unimelb.edu.au> U3364521@ucsvc.ucs.unimelb.edu.au (Lou Cavallo) writes:

>Moreover as Dave Haynie could attest to, the A2000 Zorro II buss is old news
>in todays terms. 

Bus cycle speed wise, Zorro II is in the same league as standard ISA.  The
real Zorro II innovations were AUTOCONFIG and multimastering.  You had the
latter on most industrial buses and even S-100 had a bus mastering mechanism,
but the Amiga was the first true personal computer type system to have 
these features.

>The new Zorro III buss hits 20 Mbits/sec (Dave?) and Acorns ARM III chipset 
>can hit about 38 Mbits/sec I think (can validate anyone ?).

Those are MegaBYTES/second, not MegaBITS.  I believe the 38 MB/s on the ARM 
III bus interface is correct for the faster parts.  The Zorro III bus with 
68030 as master through the Buster chip can go up to 20 MB/s (without burst),
though an alternate bus master or more efficient bus conversion device can 
drive the Zorro III bus faster (50MB/s, without burst, is the theoretical
limit).  And it's a very bad idea to compare expansion bus speeds with CPU 
bus speeds.  The 25MHz 68030, for example, has a bus bandwidth of around
52 MB/s, without burst, around 140 MB/s with burst.  But CPU buses tend to
be more specific-purpose, faster, and larger (more pins) than I/O buses.

>Lou Cavallo.


-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
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	Standing on the shoulders of giants leaves me cold	-REM