Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!snorkelwacker!bloom-beacon!eru!hagbard!sunic!mcsun!unido!mpirbn!p554mve
From: p554mve@mpirbn.mpifr-bonn.mpg.de (Michael van Elst)
Newsgroups: comp.sys.amiga.hardware
Subject: Re:   GVP Trade-in
Message-ID: <1150@mpirbn.mpifr-bonn.mpg.de>
Date: 31 Aug 90 18:20:05 GMT
References: <1898@lpami.wimsey.bc.ca> <02102.123056@thiger.UUCP>
Reply-To: p554mve@mpirbn.UUCP (Michael van Elst)
Organization: Max-Planck-Institut fuer Radioastronomie, Bonn
Lines: 24

In article <02102.123056@thiger.UUCP> skraw@thiger.UUCP (Stephan von Krawczynski) writes:
>>You are completely wrong in this. Not only is DMA faster,[...]
>right, but bus-arbitration breaks it completely up.
Only if you try to arbitrate for each cycle. When you're using
larger transfers then the arbitration isn't important.

>i know this. but tell me: is it really interesting for the customer to hear
>somthing about the scsi-bus-transferrate. especially if the controller-to-
>amigamem troughput brings the thing down to some 100 kBytes (a typical
>bottle-neck). let's talk about the real throughput, not some
>part of the story.
Well, how interesting it is in a discussion where someone experienced
states that SCSI can't run with 4MB/sec. The controller<->amigamem
bottleneck is about 3.5 MB/sec, not far away from the limits of this
SCSI controller (SCSI arbitration and command overhead might degrade
usable bandwidth to less than amiga bus speed).

Regards,

-- 
Michael van Elst
UUCP:     universe!local-cluster!milky-way!sol!earth!uunet!unido!mpirbn!p554mve
Internet: p554mve@mpirbn.mpifr-bonn.mpg.de
                                "A potential Snark may lurk in every tree."