On 6/20/07, Dave McGuire <mcguire at neurotica.com> wrote:
An RH-11 is a four-slot backplane full of cards.
And the most
static-sensitive piece of DEC equipment I have *ever* seen.
I haven't touched one since about 1988. Didn't blow it up, so I must
have been using reasonable ESD procedures (I used to make Unibus/Qbus
cards, so I'm kinda careful with that stuff).
We had a couple of RM02s attached to something with a Unibus - can't
remember exactly what, but our primary VAX there was an 11/730 (that
managed to survive 4th of July weekend during a heatwave in a closet
when the airconditioner failed - it was well over 110F in there when
we opened the door), and I know we didn't try to use an RH-11 with
that.
It was probably an 11/24 or 11/34, thinking back.
Well I'd love to have one for my PDP-11/70, but
at least I do have
other disk options for it, so it's not as urgent. The KS10, on the
other hand, is a big paperweight without a TU45 and a MASSBUS-
attached disk.
Sure.
Well, with VAXen in mind, I'd be inclined to
agree...though it's
not really that difficult to get non-MASSBUS disks on VAXen.
No, it's not. One of the easiest ways is a UDA50. At Software
Results, we had Massbus disk (RM03 as hot spares, plus an
SI-9900-to-SMD controller) and Unibus disk (UDA50 and RL11) on our
11/750. By the early 1990s, the SI9900 was the fastest, but we tended
to hang new disks off of the UDA50 rather than mess with SMD cables
and distribution cards in the disk box.
I've seen folks talk about a Unibus SCSI controller, but I've never
seen one up close. To me, that'd be a nice thing to have in an
11/750. I keep contemplating turning a COMBOARD into a SCSI
controller, but it'd be slow - the COMBOARD can do DMA to the Unibus,
but its own processor is an 8MHz 68000 which would be lucky to be able
to push over 200Kb/sec from its side (it was designed as a
communication engine, so it only had to be able to keep a 56kbps pipe
full).
Barring a wave of inexpensive Unibus SCSI cards, I think Guy's
approach is quite reasonable - build a core "storage engine" that can
stick onto either a Unibus or Massbus foundation module. That way,
everybody gets to share in economy of scale.
I'd personally be good for at least one of each, and possibly more
than one Unibus bit, if they weren't too expensive.
-ethan