System Industries QBus board

From: David Barnes <>
Date: Sat Apr 6 20:24:29 2002

sounds like you got everything but the drives, and of course an actual SI 9900
disk controller, ths 9900 controller was a rackmount box a little smaller than a
rackmount BA23 would look like... not as deep front to back.... the SMD drives
hooked to this controller, then the qbus (or UNIBUS) interface cards connected to
the controller itself... they supported an early cluster called SI CLUSTOR which
predated VMS Clustering, and also allowed multiple PDP 11's to share the same
disks... interesting to say the least... unfortunately I disposed of all my SI
docs and software in 95...

Doc wrote:

> On Sat, 6 Apr 2002, David Barnes wrote:
> > This is an SI (System Industries) interface card to the SI 9900 controller,
> > and its variants... The 9900 allowed you to attach SMD disk drives, and
> > it did RM (later MSCP) emulation with VMS... It was also supported in
> > PDP's. I used to have some of these.... interesting technology..
> Ahhh, the dawn begins to break. There's an empty 4-bay drive drawer
> that doesn't have any visble connectors, and a very beefy
> PSU/transformer set. There are also a couple of Berg connectors on the
> main bulkhead that I haven't ID'ed. The one descriptive link I've found
> for a Systems Industries 9900 refers to "its own rackmounted drawer."
> So, I have 2 identical QBus boards, and maybe the drive drawer. What
> components (including drive types) are missing here?
> Thanks for the information, too. That's miles farther along than I
> started.
> Doc

David Barnes
OpenVMS , Tru64, Netbsd, Linux guru
and collector of DEC equipment
Received on Sat Apr 06 2002 - 20:24:29 BST

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