View Full Version : Another academic PDP11 emerges -

December 25th, 2009, 05:02 PM
So here's the story to date -

Jason posted a notice re the system at approximately 2:00 AM Thursday
morning; I saw his note at 6:45 AM and responded to the Craig's list
advertiser, indicating that I could get the system on Friday. I planned on
renting a van for the retrieval. I didn't hear back from him until I was
already at work and his answer wasn't good. He informed me that the system
had to be removed immediately since the scrapper was due on Friday (they
were having a building-wide cleanup at the IIT Engineering Center).

I mentioned my predicament to a co-worker who just happened to have driven
his van to work that day (he usually takes the train). Mark thought the
rescue would be fun (really - no arm twisting!) and I didn't try to
discourage him. At 2:00 PM we were on our way to the IIT campus which is
only 10 minutes from work. It had been an extremely busy day and I didn't
have any tools or any more info on how to attack the drive to lock the heads
but just figured we'd wing it.

When we finally found the right building, right entrance and right driveway,
Alex, the Craig's list advertiser, was already outside looking for us. He
took us down to the basement and guided us to the appropriate area then left
to go back to work. We found a full DEC rack, including a pristine PDP-11
"crest", with the 11/34, Telex 9-track tape drive and third-party 8" floppy
drive. Next to it was a "high boy" cabinet with an RL02. Next to that was
another 8" floppy drive and another RL02. Nearby were 8 disk packs and
various PDP-11 manuals. A carton contained several 8" floppy boxes,
including several with RT-11 system labels. Lots more debris - mostly
glassware, commodity PCs and monitors, weird componentry, etc. There was a
port on the back of the rack labeled "Tek 4010" but no sign of the terminal
- finding that would have really made this an otherwordly experience! The
engineering students scurrying by seemed only moderately interested in
watching two geriatric-types pawing through the piles of discards.

First step was the big rack. Once we got it on the elevator and out to the
van, it was clear that not only was it very heavy but that it would pretty
much fill the available space (Mark's van is a Toyota with flip down but not
removeable seats). With a lot of grunting, we got the rack tipped and up
onto the seat backs. From there, sliding it into the van wasn't too bad but
it was clear that we could only fit the one rack and not the other cabinet.
We managed to fit most of the other relevant "stuff" in and around the rack.
This meant that we were taking the loose RL02 without being able to open it
to check for disk pack or head lock. At this time I hadn't heard back from
Ethan nor had I been able to access bitsavers to check the docs so when the
disk cover didn't release, I had no idea what to do next. I tried to get a
few students to log me onto a public station to I could use the 'net but
they didn't have current IDs (or maybe they were just freaked out by my
request). We very carefully carried the drive out to the van and loaded it
onto the front seat for the short ride back to work. I rationalized by
thinking that it had already been moved around the basement and we were only
increasing the risk of damage slightly. We'll see. Once back, unloading was
easy with help from a couple of maintenance workers and the system was
stowed securely in my coms room. Mark had to go back to work but he let me
take the van to get the other drive.

I now had time to hit bitsavers and see how to open the drive and lock the
heads. Armed with knowledge and the appropriate tools (Leatherman), I headed
back. Locking the drive heads was easy - four screws to remove the top cover
(glad I did - there as still a disk in place, dated 1984) and a small screw
to position the locking plate. Done. But I couldn't figure out how to unrack
the drive. I spent at least 20 minutes messing around with screws and
latches but couldn't find the final release to get the unit out of the
cabinet. I could extend it, retract it, lock and unlock the shipping plate,
etc. but I never found the secret release. In the process, I found out that
the bottom of the cabinet contained some sort of auxiliary processor with
coaxial feeds and paddle cable connects back to the main system. I couldn't
ID it but it was definitely heavy. I did manage to remove it from the
cabinet - _this_ rack worked in a straight forward way with a few detents to
release the unit - and lower it to the floor. With the heads locked and the
bottom components removed, I went back to trying to remove the RL02. I still
couldn't get it done - even with the cabinet tipped sideways on the floor
and the actual rack screws removed. I tried to remove the rack side panels
so that I could remove the top trim pieces and take to drive out from the
top but I couldn't get them off. Finally, I just stuffed the drive back into
the cabinet. Alex was still there and he helped me to get the cabinet and
final bits into the van.

I was finally done and ready for beer by 7:00PM. Everything is safe at work
but I won't be able to inventory it until I go back in on Monday. At that
time, I'll have pictures and a better idea of what I've truly rescued.

Thanks to everyone who offered help and encouragement, and especially to
Jason for spotting the ad in the first place.

(pix and description to follow in subsequent messages)


December 25th, 2009, 05:36 PM
OK, so here are the details -

One full size (H960)rack cabinet containing (from the top down) -

DEC PDP-11 crest
Telebyte TDX 1/2" tape drive
PDP-11/34A w/ full programmer's console
Data Systems Design (DSD) 880-120
homebrew connector panel
Wesperline I/O unit

One "corporate highboy" cabinet (VAX style, don't know the p/n)

RLO2 drive
BA11-KE chassis

non-racked items -

2nd RLO2 drive
DSD twin floppy system, 110/430

additionally -

8 disk packs + "pack rack"
several boxes of 8" floppies, including an install set for RT-11 V5.1c, configured by Cambridge Digital, dated 1984

card inventory (by chassis slot) -

- 11/34A (chassis marked 11/34A XX)
(1) M8266 control module (KD11-EA)
(2) M8265 datapath module (KD11-EA)
(3) M8267 floating point (FP-11A)
(4) M7859 programmer cons (KY11-LB)
(5) M8268 cache board (KK11-A)
(6) M7801 data word cntrl (MC11)
(9)<->(11) M9202 backplane jumper
(12) DSD 808830 controller for DSD 880-120
(13) DILOG DU130 tape controller
(14) M7865 SLU+RTC (DL11-W)

- BA-11-KE
(3) M7860 parallel I/O (DR11-C)
(5)&(6) MSP-3/A, MSP-3/C Computer Design Assoc. boards
(8 ) M7762 RL02 disk controller (RL11)
(9)<->(11) M9202 backplane jumper
(12)&(13) MDP-3/M CDA boards (includes 4 AMD 2903 SuperSlice chips)

Reviewing the list, I'm pretty sure that the card in slot 6 of the CPU chassis must be an M7891 variant; probably 128KW of MOS memory.

Pictures at: http://tinyurl.com/pdp1134a


December 25th, 2009, 06:13 PM
Wow. What a rare find. At the right place at the right time.

December 25th, 2009, 07:33 PM
I'm thinkin 5 to 8 grand.

December 29th, 2009, 09:05 AM
Nice find! I have a similar system which awaits restoration.

January 12th, 2010, 05:38 PM
So here's the story to date -

Jason posted a notice re the system at approximately 2:00 AM Thursday

So Jason is the person who saw my post on cctalk at first ?