Simulated disk drive for RT-11? - test-drb@ccmp.vtda.org

6 Jun 2005

...

Subject: Re: Simulated disk drive for RT-11?
   From: "Jerome H. Fine" <jhfinexgs2 at compsys.to>
   Date: Mon, 06 Jun 2005 19:26:16 -0400
     To: General Discussion: On-Topic and Off-Topic Posts <cctalk at
classiccmp.org>

 Ethan Dicks wrote: 
  On 6/6/05,
Kevin Handy <kth at srv.net> wrote:   

 You could make one like DEC used to: Take an
8-slot backplane, and
fill in four of the slots with epoxy. You now have a 4 slot backplane.

 Ahhhhgggg!  Ever seen that with a BA123?  Makes you cry... DEC didn't
want their graphical workstations being converted to departmental
server use, so they plugged up the extra holes in the backplane to
prevent expansion.  For a while, one could order a virgin backplane
from spares, but they eventually caught on (then they stopped hosing
workstation customers so much ;-)

Fortunately, I've only ever seen it at a DECUS (DEC-owned demo
machines); none of the machines I've worked with or personally owned
were broken this way.
 Jerome Fine replies:

In the interest of proving that it was done (I
suppose that this is NOT proof that DEC did the
foul deed), I saved one of those backplanes from
an old BA23 box.  As a matter of record, only the
last 3 slots have epoxy.  If anyone wants the proof,
I will save it for you since it is about time to
toss it in the trash where it belongs.  By the way,
as Antonio states below, this backplane is an 8 * 4
slot from a BA23!!!!!!!!  Maybe Ethan's finger slipped
and added an extra "1" after the "BA"?????????????
I can't see that DEC would have converted a BA123,
but I guess that DEC could have done anything at that.

 Antonio Carlini wrote: 
 This was the (thankfully) short-lived VAXstation
II/RC. The
one I saw came in a BA23, not a BA123. There were companies
around that would (allegedly) remove the epoxy (or whatever
it was they used) and hence restore full functionality. 
Just so I could say I tried, I once spent a few
hours attempting to remove the epoxy - not a cost
effective use of my time.  I suspect that these
companies were more likely to have either purchased
a replacement backplane or found a damaged BA23
with a good backplane and removed the good backplane. 
Thats what FS did!

Note there were differenet backplanes used in the BA23 those
that were compatable with uVAX-1, those that were uVAX-II
and the microPDP-11. Use the wrong one with the desired CPU
and bad results happen.

Allison