Re: LSSM VAX-11/780 success - HECnet

27 Nov 2025

   A few additions.  Owen and I were working on it most recently; Matt 
and Richard are not in town now.  But both have put effort into it.  A 
lot of us have; this poor machine took a lot of work to get going.

   You missed its initial troubles just before your first visit.  We 
picked up the machine that summer of 2017 and it was a MESS.  From 
memory, I hope I don't miss anything, here are the things we worked on 
initially:

   It had an FP785 installed; we removed it and installed baffles. (will 
an FP785 even work in an 11/780??)  We left the first power supply in 
place in case we find an FP780 board set.

   Three of its four power supplies needed bench work.  The fourth was 
fine. (We don't know the status of the FP780 power supply yet; we'll 
look into that if we ever find an FP780.)

   The console PDP-11/03 was missing, I built one from parts.

   The backplane covers were missing and there were a few groups of 
mashed pins.  We straightened those, and found and installed the covers.

   There was a UBA, but no Unibus chassis.  We put together a BA11-K for 
that.  (We later found its original Unibus chassis.)

   Later after Terri spent DAYS tediously combing out the huge mess of 
board revisions (the previous owner kept swapping things around trying 
to get it running) she got all that straightened out and then figured 
out what WCS version we needed.  Mike up at RICM was able to supply a 
copy, but their disk imaging system was down so he just sent us the 
whole box of disks.  We imaged them and sent them back, and I pieced 
together what should look like an original distribution 11/780 console disk.

   This was a big thing for me personally too.  All my life I've been a 
"DEC guy"; I've had VAXen at home since I was 20 years old, which was 36 
years ago, almost as long as I've had PDP-8s and PDP-11s.  My first 
"real" industry job was as an admin on a set of VAXen, one of which was 
an 11/750.  But until last night, I had never been in the same room as a 
running 11/780.  It hit me deeply and felt really, really good.

   And it was fitting for Owen; he was at the console during the first 
complete boot, and yesterday was his 65th birthday.  A few of us took 
him out for tasty Indian food right after that boot.

              -Dave

On 11/27/25 04:45, Terri Kennedy wrote:
...
  On 2025-11-27 02:56, Keith Halewood wrote:
  Great news. I hope you'll be publishing some
pictures (perhaps before,
 during after) of the restoration on the website?  
    There aren't a lot of pictures (at least I didn't take many).

    A lot of it was just basic mechanical stuff - fixing a seized
 spindle and decayed drive belt on the floppy drive and then im-
 aging a number of floppies with the console software and a bunch
 of diagnostic discs. Dave did all of that.

    Then there was an interesting project to come up with outlet
 strips to plug all of the individual component AC power cords
 into, since there wasn't an L21-30R receptacle there at the time
 to plug the single "official" power cord into. This will be ad-
 dressed now that it is a functional exhibit.

    After reseating some cards, Dave and I were able to use a
 cheat I knew of to get past the console complaints about mis-
 matched hardware and we got the first ">>>" prompt in over a
 decade. At that point, "BOOT DU0" would actually go initialize
 the disk controller and turn on the port select on the drive,
 but not go past that point. At that point, we knew we at least
 had a VAX, although a very sick one.

    At that point, Dave imaged some other console discs and I
 then edited the contents using RT-11 on another system (the
 LSI-11/03 that controls the VAX runs a very modified version
 of RT-11).

    Next, there was an assortment of boards which were neither
 compatible with each other, nor with the console microcode.
 I discovered the Museum had nearly a complete 780 board set as
 well as some 785 boards, and spent several days with all of
 the boards and DEC's official "VAX-11/780 & VAX-11/782 Revis-
 ion Control" document to bring the system up to revision 8.B
 which is the newest 780 revision. I then spent a few more
 days weeding out bad boards.

    At that point, the system went from saying "Help me!" (see
 the first photo) to actually booting to the VMS version banner
 for the first time in many, many years (second photo) but then
 hanging.

    Dave, Owen, Richard and Matt P (apologies if I missed any-
 one, I'm doing this from memory) then discovered that I'd
 missed a bad board, which caused "console transit done" in-
 terrupts to not be seen by the VAX. This past evening, they
 got the 780 to boot, first NetBSD and then VMS. It is also
 now passing diagnostics.

    Now the work begins to neaten things up, get it the power
 cabling it wants, and configure the console floppy so that
 it can boot VMS, Ultrix-32 or NetBSD, depending on what sort
 of demo will be given.

    Dave says this is the first time he has been in the same
 room as a working 780. Yay! And a big shout out to all of
 the volunteers who have been working to get this system run-
 ning, with work starting all the way back in 2018!

    Th last picture is the inside of the 780 in all of its
 glory. It isn't on in this picture because the air baffles
 need to be in place in front of the cards to keep the CPU
 from overheating and going into thermal shutdown. So this
 picture was "posed" to show the board set, before putting
 all of the air baffles back in place.

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-- 
Dave McGuire, AK4HZ
New Kensington, PA