Odd problem with AHA1542B, Archive tape, and Micropolis disk

[Karl Denninger]

In article <1990Sep19.042306.261 at esegue.segue.boston.ma.us> johnl at esegue.segue.boston.ma.us (John R. Levine) writes:
>I have a 386 box with an Adaptec 1542B controlling a 660MB Micropolis disk.
>Works great.  I'm trying to add an Archive 2150S SCSI tape drive with no
>success.  The tape's in the middle of the cable with no terminator, and has
>its ID set to 5.  I can't get ISC Unix, which is reported to work perfectly
>well with this drive and controller, to admit that the tape is there.
>
>The problem seems to be that the disk is responding to all 8 SCSI addresses.
>When I run the diagnostic in the adapter BIOS, it reports that there is a
>disk at every SCSI address.  The disk has jillions of jumpers on it, but of
>course arrived in a documentation-free condition.  While I attempt to
>explain to my dealer what the problem is and to get them to find a manual
>for the disk, does this problem sound familiar?

Yeah, a number of disks are crass enough to do this.

Make sure that the disk isn't selected as Unit 7.  Some disk drives like to
show up on all 8 bus addresses if you set it for 7, presumably because that
makes single-drive installation easier (you don't have to change any
jumpers).

I bet your drive is in this condition.  If so, removing one or more of the
drive select jumpers (probably ALL of them) will get you Unit 0, and the
problem will go away.

Note that if you want to boot from the drive it should be at Unit 0, and
further that the tape drive must be at a higher SCSI address than any of the
disks in the system.  I usually use Unit Select 4, since ISC's standard
driver supports 4 SCSI drives (and thus unit 4 is safe no matter how many
drives are actually installed).

--
Karl Denninger	AC Nielsen
kdenning at ksun.naitc.com
(708) 317-3285
Disclaimer:  Contents represent opinions of the author; I do not speak for
	     AC Nielsen on Usenet.