Overland T490 cartridge tape drive and autoloader

nico de jong nico at farumdata.dk
Fri Dec 10 03:35:06 CST 2021

Hello Peter
Yes, the drive is 3480 compatible.
I have only seen them as "normal" SCSI, but that is not the same as 
saying that differential versions do not exist.
I believe I have a manual somewhere, but can't look into it until mid 
next week
I'll get back to you if I find it

On 2021-12-09 22:20, Peter Coghlan via cctalk wrote:
> Many years ago, a friend gave me an Overland T490 tape drive which has
> some kind of autoloader attached which takes ten tapes.  I was told it
> came out of a Tandem system.  The tapes are square cartridges similar
> but different to a DEC TK50.  I can't find very much information about
> the drive on the web but there are some hints that it might be compatible
> with an IBM 3480.  It powers up nicely and the fan works and after a
> short pause, a green LED illuminates.  There are only two buttons on
> the front, "unload" and "format".
> There are two DD50 connectors on the back.  One had a terminator plugged
> into it labelled "SCSI differential".  The other had a ridiculously long
> cable with DD50 plugs on it connected, lending further credence that
> this is a differential (pre-LVD I expect) SCSI device.
> I would like to get this drive working with my Alpha or VAX VMS systems
> but I have never had any luck getting them to talk to it.  Recently,
> I tried a using a DD50-HD68 cable I found somewhere to connect it to
> a differential SCSI card in my Alphaserver 800 but I could not get VMS
> to see the drive.  Not knowing what SCSI id the drive is likely to be
> using makes it hard to know where to start looking for it.
> There are no switches on the outside of the drive which could be used
> to set the SCSI id so I opened it up to see if I could find any hints
> inside.  I didn't see anything that looked like it could be used to
> set the SCSI id inside either.  What I did find is that the interface
> board had a connector labelled "SCSI differential" which had two short
> lengths of ribbon cables plugged into it leading to the two DD50
> connectors on the rear panel and another connector labelled
> "SCSI single ended" with nothing attached.  There were also two ten way
> jumper packs which were labelled "DI" and "SE" on each side.
> So, not having any luck with differential so far, I tried moving the
> two jumper packs from "DI" to "SE" and moving the ribbon cable to the
> "SCSI single ended" socket.  I used a short, known good DD50-DD50 SCSI
> cable to connect the drive to my VAX 4000-100A and replaced the
> differential terminator with a known good single-ended terminator.
> VMS didn't see the drive.  VMS has a utility called scsi_info which can
> be used to send a SCSI inquiry command and read mode pages etc.  Trying it
> against each unused SCSI id results in "device timeout" every time.  The
> system disk is on the same SCSI bus before the tape drive and a SCSI
> scanner can be connected after it on the bus.  Both devices work fine so
> the SCSI bus cabling and termination is in good shape on both sides of
> the tape drive.  I've tried moving the system disk SCSI id from 0 to 1,
> changing the initiator SCSI id from 6 to 7 and replacing the scanner with
> a terminator in case there is any sort of SCSI id conflict but scsi_info
> still doesn't show up anything that could be the tape drive.
> Does anyone have any information about this drive, particularly
> whether it should behave like a standard SCSI tape drive and what
> SCSI id and/or lun it is expected to use or if there is some trick
> required to get it to start talking? Maybe it doesn't like SCSI
> inquiry commands?
> Extra bonus points awarded for details on how to control the autoloader.
> Maybe I did some damage to it when I was trying to get it to work when
> I first got it?
> Regards,
> Peter Coghlan.

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