Having problems with SCSI MO drives

From: Jerome H. Fine <jhfinexgs2_at_compsys.to>
Date: Wed Sep 8 22:14:58 2004

>Vintage Computer Festival wrote:

> >On Wed, 8 Sep 2004, Jules Richardson wrote:
> > Hmm, do check that the drives don't have their own termination jumper
> > that's set - having the bus terminated twice at one end could cause all
> > sorts of problems (and in theory damage devices on the bus, although
> > I've never seen that happen in practice)
> The problem is I'm trying to get a system working with several different
> old MO drives (Maxoptix Tahiti 1, Pinnacle Micro REO-650/1300, Sony
> <forgot the model>). The Maxoptix is not even being recongized, and may
> well be dead dead dead. The Pinnacle is being recognized but I'm getting
> the errors mentioned. The Sony drive gets recognized OK and the system
> boots but then I get a bizarre message in the Adaptec BIOS that says it's
> not a disk drive(!) Well then what is it? It's a Macinstor drive (ugh,
> can't think...forgot who the manufacturer is).

Jerome Fine replies:

I am not sure if my experience will help or not, but just in case:

BUT, first I should mention that I use an Adaptec PCI card:
an AHA-2940AU with the MO drives on the external connector,
so my experience MIGHT not apply to the ISA 1532 card,
although, IIRC, I think was using a 1532 card in my old system
about 3 years ago with about the same sort of problems!

I have used both Pinnacle Micro REO-650 and Sony SMO S-501
drives at the same time on the same daisy chain. In general, I rarely
have difficulty when there are multiple Sony drives on the SCSI bus.

However, the Pinnacle REO drives are probably NOT cabled correctly
since they usually are a problem, especially when the Pinnacle MO
drive is the first in the chain. If you look inside the box, my experience
has been that the centronics 50-pin connectors are NOT at the ends
of the cable connected to the drive; with my Pinnacle REO-650 drive,
the drive is at the END of the cable and one of the 50-pin centronics
connectors is connected to the middle. While this configuration does
not always cause a problem, even when there are just 2 MO drives
(including 1 Pinnacle REO-650 drive), at this point, I ALWAYS avoid
using any Pinnacle REO-650 drives UNLESS it is just ONE drive on
the SCSI daisy chain.

In addition, even when I used ALL Sony SMO S-501 drives, I found
that the AHA-2940AU was NOT able to support more that 3 such
Sony SMO S-501 drives, IIRC! I might have used 4 drives 1 or 2
times, but certainly NOT on a regular basis since the SCSI daisy
chain seemed unable to support more than 3 SMO drives in my
system. NOTE, however, that part of the problem could have been
a rather long SCSI cable (about 6 feet) prior to where the first
Sony SMO S-501 drive was connected to the SCSI daisy chain.

For a while, I was using the 3 * Sony SMO S-501 drives under
Windows 98 SE with E11 and RT-11. I also had a Sony SMO S-501
drive on a real DEC PDP-11 system with a CQD 220/TM SCSI
host adapter. The primary purpose was for backup on both the
PC and the PDP-11, but on some occasions, I used the MO media
in production on the PC at the end of the session with a RAM: disk
under E11 as the active RT-11 device since the MO media were
so slow.

Sellam, does this information help?

Sincerely yours,

Jerome Fine
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Received on Wed Sep 08 2004 - 22:14:58 BST

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