[Simh] Simh Digest, Vol 158, Issue 14

[William Pechter]

There were 3rd party Unibus to Qbus converters that would handle the signal
Mux/decus issues on the bus lines. 

I never saw any on 11/780 class boxes. 

Crappy UBA was slow.  Most were used to
put Unibus peripherals on Qbus Vaxes. 

Bill

-----Original Message-----
From: Clem Cole <clemc at ccc.com>
To: William Pechter <pechter at gmail.com>
Sent: Thu, 09 Mar 2017 15:19
Subject: Re: [Simh] Simh Digest, Vol 158, Issue 14

On Thu, Mar 9, 2017 at 2:54 PM, William Pechter <pechter at gmail.com> wrote:

> There was no DH11 driver until the DHV Qbus... And who knows what that was
> compared yo real DH11.


​Let me try to decode that time line and the implications ...


   1. VMS does not officially support the DH11/DM11 combination (ever)...
   (because of your earlier comment about officially not supporting full Unibus
   DH/DM backplane on the UBA - which makes sense.
   2. As Al points out there were DECUS drivers in the wild for them.
   3. At least one of the 3rd party vendors does develop a DH11/DM11
   compatible board which becomes native for UNIX (BTW - we should check the
   Ultrix SPD - I wonder what Ultrix says about -- I bet Ultrix recognizes it,
   but its not in the SPD).
   4. Through the days of the UBA based Vaxen with a full PDP-11 style
   unibus, customers (like me) used either real DH11s with afterwork DH clone
   or in an unsupported bus situation  for UNIX as a minimum. By point 2, we
   can assume the VMS customer are doing the same thing, but we don't have
   anyone that "did it."
   5. Time goes forward, DEC develops the DHV Qbus board.
   6. Was there a Vax based system that had a UBA that spoke QBUS? I
   don't remember such a beast in ZK in the Ultrix lab, and we did not have
   one in pile of gear we at LCC in those days.
   7. Assuming 6 is yes, does that mean VMS supported the DHV on same?
   Again - I do not know.

William do you agree from the HW standard point...  I can verify the UNIX
side of things, but 10 years  development from 1980-'90 I just was not
close to the Vax as I was doing other things.   I got back in early 90's
when LCC took over Ultrix development and Vax support came with the
contract; but I admit I did not as much atten as I had in the 70s,

Clem