Path: utzoo!attcan!uunet!aplcen!uakari.primate.wisc.edu!sdd.hp.com!mips!sjsca4!poffen
From: poffen@sj.ate.slb.com (Russ Poffenberger)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: MFM & SCSI controllers co-existing?
Message-ID: <1990Aug29.165815.18685@sj.ate.slb.com>
Date: 29 Aug 90 16:58:15 GMT
References: <2247@sud509.ed.ray.com>
Reply-To: poffen@sj.ate.slb.com (Russ Poffenberger)
Organization: Schlumberger Technologies, San Jose, CA.
Lines: 40

In article <2247@sud509.ed.ray.com> heiser@tdw201.ed.ray.com writes:
>
>I have a 386 machine running Unix (Esix);  the system has an Adaptec
>1542b SCSI controller and a CDC Wren IV drive.  I also have an mfm
>drive that I may take out of another machine, to be used as a backup
>medium while I'm saving my pennies to buy a tapedrive.
>
>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?)
>
>Anyone there with this config doing this?  If so, what kind of mfm card
>should I get, and how do you have your adaptec & mfm cards configured?
>
>Thanks in advance,
>
>Bill
>
>

Yes, the AHA 1542B can co-exist with an MFM controller, I have done it
with a Western Digital WD1003. The only problem is that the 1542 can no
longer be the boot drive, the MFM becomes the boot drive. This is not a
limitation of the 1542, but because of the way the system BIOS works.

The system BIOS will probe for things it knows about (ie MFM controllers,
video cards, etc) before probing for BIOS extensions (such as the one on
the 1542), this means that upon finding the MFM controller, it is assigned
as the first hard disk, then later, as the 1542 BIOS is invoked, it will
install any SCSI drives after the MFM drives.

Just make sure that the BIOS addresses for the controllers are at
different places. The 1542 can be re-configured, many MFM controllers
cannot, so they sit at C800, you will probably want to put the 1542 at
CC00 or D000. (check for video bios conflicts here).

Russ Poffenberger               DOMAIN: poffen@sj.ate.slb.com
Schlumberger Technologies       UUCP:   {uunet,decwrl,amdahl}!sjsca4!poffen
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