BA23 vs. BA123 vs. 42" cabinet?

From: Andreas Freiherr <Andreas.Freiherr_at_Vishay.com>
Date: Sat Apr 6 14:53:23 2002

Doc,

in a 42" unit rack, the term _Micro_VAX wouldn't quite correctly
describe the machine.

> I'm not enamored of the idea of running a 240VAC rack in my garage if
> not necessary. That leaves me with two other ideas.
>
> 1) The "drawers" are simply BA23 enclosures, right? Any reason I can't
> use the primary enclosure as a stand-alone unit? It's going to be
> running a minimal set of hardware:

No reason not to do this. DEC made plastic covers to hold these boxes in
exactly this position on a desktop. The same skin with a floor stand
attached to its left side was the pedestal box.

> KA655 CPU
> Dataram 63016 16M RAM
> DMV11 (simply to occupy the last CD slot)
> DEQNA/DELQA (whichever I can scrounge cheapest, first)
> TQK50 (undecided)
> RQDX3 (with probably only the RX50 or an RX33 attached)

Looks OK. However, you should be able to omit the DMV11 if you don't
actually want to use it: the DEQNA and DELQA are dual-width modules, so
each of them will nicely fit into the A/B alots without touching the C/D
interconnect.

> That _is_ the right bus order, isn't it?

I think so, too.

> Will either the power requirements or cooling be a problem? What if I
> decide to run the RD54 instead of the TK50? Is it OK to run the BA23
> without skins, lying flat?

Without actually adding up the power requirements: You should be able to
run a RD54 _and_ a TK50 in the same box. Many MicroVAXes were configured
that way. Even if the KA655 uses significantly more power than the
KA630, you will most probably be safe because you don't have too many
modules in the bus.

> And, if I want to run the second backplane and extra drives, can I
> just stack them?

You can, but wouldn't it then be easier to use a BA123 right away? It
provides almost exactly the same features as two BA23s, but it doesn't
need the cables between the halves of the bus, it has only one power
cable and switch, etc. etc.

> 2) I can put all the above in the BA123 lurking downstairs. But it
> seems a huge waste of space & power over the BA23. Plus, I don't have
> cooling vanes for the dual cards in the added CD slots, or enough
> D<mumble>11 boards to go around. Plus, the BA23 I can wedge into my
> office, but the BA123 would have to live in the garage.

Must be a very small office. Anyway, living in the office sounds better
than living in a garage, so why not go for the BA23?

Andreas
Received on Sat Apr 06 2002 - 14:53:23 BST