Xref: utzoo comp.sys.ibm.pc:47162 comp.periphs.scsi:241
Path: utzoo!attcan!uunet!xstor!iverson
From: iverson@xstor.UUCP (Tim Iverson)
Newsgroups: comp.sys.ibm.pc,comp.periphs.scsi
Subject: Re: MFM and SCSI together ?
Message-ID: <6@xstor.UUCP>
Date: 26 Mar 90 20:19:59 GMT
References: <1969@crash.cts.com>
Reply-To: iverson@xstor.UUCP (Tim Iverson)
Followup-To: comp.sys.ibm.pc
Organization: Storage Dimensions, Inc.
Lines: 64

In article <1969@crash.cts.com> jca@pnet01.cts.com (John C. Archambeau) writes:
>I based my assertion on trying to hang an ESDI and ST412/506 controller
>at the same time on the same machine.  Doesn't work too hot.

This is correct.  Both ESDI and ST506 typically attempt to be WD1003
compatible, since clone BIOSes support that register set directly.  This is
why most *ESDI* and ST506 boards have "IRQ and i/o port wars".  Most SCSI
board vendors have chosen to *not* support the WD1003 register set and
instead to put their own BIOS on the adapter.  This makes the boards more
hardware compatible, but more expensive to design.

>[...] I personally stick with only Western Digital, is
>the same true for the WD7000 SCSI Host Adaptor?  If so, then I'd love to hear
>it.

I've used the wd7000(FASST - a misnomer); I don't care for it.  I haven't
used it sufficiently to comment further - unless lotsa people mail and
beg me for my purely subjective judgements :-).

>Also, I didn't say that what I said was the gospel truth, just an
>educated guess considering I know some of the horrors of SCSI and the IBM
>compatable domain.

Unfortunetly, in the this area your educated guess is serious misinformation
at best - at worst, it is a bald lie.  If you cannot restrict yourself to
reporting facts, do not post.

>[...] Granted, you may be able to
>do it, but also think from the practical standpoint, why would you want to? 
>You have this slow drive that's running ST412/506 MFM and a SCSI controller
>with possibly a Wren IV to VI running like a bat out of hell. I wouldn't do
>it just for the sake of system performance [...]

In your previous article, you lambasted vendors for second guessing the
users' needs.  Here, you are guilty of that yourself.  Perhaps the user
will use the quick subsystem for work and the slow one for backup (after
all, it works and he already owns it).  Also, the presence of an ST506
subsytem in a system with a SCSI subsystem in no way degrades the
performance of the SCSI subsystem - the two are mutually exclusive.

In a multitasking OS, if the subsystems are used concurrently, and if the
SCSI H/A does 1st party DMA, then the 1003 compatible subsystem will
degrade overall system performance more than the SCSI subsytem.  When the
1003 subsystem is not being used, system performance is not impacted at
all.  Running slowly during backups usually considered acceptable.

>As for Novell, the only thing that is 100% Novell approved is Novell's DCB

This is another outright lie.  SDI markets both ESDI and SCSI (non DCB)
subsystems that are 100% certified.  SDI also markets a 100% certified
fileserver (basically a 33Mhz 386 optimized for disk i/o).

> // JCA
> ** ARPANET : crash!pnet01!jca@nosc.mil     | mine.  Bill Gates couldn't buy
> ** INTERNET: jca@pnet01.cts.com            | it, but he could rent it.  :)
> ** UUCP    : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jc

To paraphrase Joe Friday, "Just the facts, man".  Being wrong is no crime,
its the degree of the act that makes it a felony.  Please stick to what
you know to be true when you post as an "authority" on a subject.


- Tim Iverson
  uunet!iverson!xstor