HP 88780 / 7980XC Interface Question

From: Frank McConnell <fmc_at_reanimators.org>
Date: Thu Apr 11 11:27:43 2002

"Douglas H. Quebbeman" <dquebbeman_at_acm.org> wrote:
> I see lots of references to these drives...
>
> Do they possess multiple interfaces, or do you get
> one that has the interface you need?

You get one that has the interface you need, but I think you
can swap interfaces; e.g. I've swapped a single-ended SCSI
interface board into one that I got with a differential SCSI
interface. Note that the interface board is screwed to the
back plate which has the cutout for the connector, so if
you get a different interface board you may also want to get
the appropriate back plate for it.

> I've seen one with an HP-GPIB interface connector
> on the back, and was wondering if I pull that rear
> cover off, will I find a set of Pertect interface
> connectors hiding there? Or is that simply a different
> model?

I haven't looked inside one with a Pertec interface, but the SCSI
interfaces expect to plug into a flat cable that is in the base of the
drive and I expect the Pertec interface would too.

There's also a four-slot card cage in the right side of the drive,
accessible by removing a top cover. The boards installed in this cage
make a difference too. Later drives have only three cards installed
(the read/write/PLL boards and formatter board were replaced by a
single board).

7980A and 7980XC are HP-IB-interface drives sold into the HP
minicomputer markets. The XC suffix means the drive was sold with a
variant board that supports data compression (meaning you can write
tapes that are only readable by other 7980XCs).

7980S is the same drive with a SCSI (single-ended I think) interface,
sold into the HP minicomputer market. At one point HP offered a
field upgrade kit to change your HP-IB drive to a SCSI drive.

There is also a variant board that supports 800 BPI (in addition to
1600 and 6250). I believe that 800 BPI and XC compression are
mutually exclusive (you can't have one drive that does both).

7979A is an HP-IB-interface flavor of the drive that supports neither
6250 BPI nor data compression. I'm not sure but this may simply be a
different-variant board as well.

88780 are drives sold outside the HP minicomputer markets, including
OEMs like IBM, Sun, and Tandem. Of course the OEMs came up with their
own model numbers.

I have some notes that say data compression was option 400 and 800 BPI
was option 800, but I'm not sure whether this applied to a 7980 or
88780.

-Frank McConnell
Received on Thu Apr 11 2002 - 11:27:43 BST