Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!snorkelwacker!apple!altos!altos86!rcollins
From: rcollins@altos86.Altos.COM (Robert Collins)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: MFM & SCSI controllers co-existing?
Message-ID: <3878@altos86.Altos.COM>
Date: 29 Aug 90 19:16:08 GMT
References: <2247@sud509.ed.ray.com>
Reply-To: rcollins@altos86.UUCP (Robert Collins)
Organization: Altos Computer Systems, San Jose, CA
Lines: 30

In article <2247@sud509.ed.ray.com> heiser@tdw201.ed.ray.com writes:
>
>Can I use an MFM card along with the SCSI card?  I would want to keep
>the scsi drive as the "primary drive" (LUN 0), and have the mfm 
>drive something after that.  (is this possible?)
>
It is possible for SCSI and ST506 to coexist.  If both controllers have
adaptor ROMs then one will have to be jumpered so it doesn't interfere
with the other.  As for the SCSI LUN=0, that will have no effect on 
which device appears as device 80.  If the ST506 is supported by the BIOS,
then the MFM will appear first as device 80.  This is because ST506
gets installed before adaptor ROMs.  If however both the ST506 and SCSI
are on cards that have adaptor ROMs, I think if you jumper the SCSI before
the ST506, then the SCSI would be device 80.  But, the monkey wrench is
that I seriously doubt the ST506 code is on adaptor ROM -- as all 386
BIOSs support ST506.  

At my work, I wrote the entire SCSI code, and encorporated it into the
Phoenix BIOS.  I deviced a technique known here as "drive mapping" that
allows you to map the SCSI as device 80 and make ST506 the next logical
device.

The answer to your question is that it is possible, but you would most
likely have to modify the BIOS -- which would require the source code.

-- 
"Worship the Lord your God, and serve him only."  Mat. 4:10
Robert Collins                 UUCP:  ...!sun!altos86!rcollins
HOME:  (408) 225-8002
WORK:  (408) 432-6200 x4356