Rescuing two PDP-11s from a former British Telecom underground shelter (2023)

108 mhh__ 21 7/23/2025, 6:02:40 AM forum.vcfed.org ↗

Comments (21)

timonoko · 8h ago
I saw PDP-8 and two ASR-33 on a garbage pile in around 1980. I knew that if I take them, it will destroy my life, I would do nothing else than tinker those for the rest of the millennium.
PaulHoule · 4h ago
If you think the 6502 doesn't have enough registers and addressing modes... Try the PDP-8.

The PDP-11 on the other hand has a lot of registers and addressing modes. A kid with a TRS-80 in 1980 might have thought the "16-bit" PDP-11 looked like the future although it really was the past, as it dated from 1970. The greatest weakness of it was that the user had a 16-bit address space so a PDP-11 running RSTS/E gave everybody a BASIC experience a little bit better than an Apple ][ or alternately the ability to run applications similar to CP/M. The machine as a whole had more than 64k of RAM but as a user you got 64k of code and 64k of data -- so it was a little bit better than the 8-bitters of 1980 but not as good as the IBM PC for having a bigger "problem space" to work on bigger problems.

My high school got a VAX to replace our PDP-8 and the computer club got it. We had two video terminals and a printing terminal, originally the printing terminal was the main terminal that was used when the machine was brought up in single-user mode. I swapped in one of the video terminals in this role, powered it up, and had the VDT catch on fire -- so we cleaned up the other terminal before bringing the machine up with that.

dhosek · 4h ago
That’s why, when the local college was decommissioning their IBM minicomputer, I opted not to buy it (it would have been under a thousand bucks, as I recall, although I probably would have spent that much a month on air conditioning if I set it up in my apartment, not to mention the overall impracticality of it.
SoftTalker · 5h ago
Working on a teletype at 110 baud gets old really fast.
WalterBright · 3h ago
I couldn't stand those ASR-33's. I'd wait until a Decwriter was available (300 baud).
glimshe · 3h ago
When I started doing BBSs, I used 300 baud at times. Unbearable. "Nobody ought to need more than 2400 baud" is what I felt with the upgrade! Until 14400 came along, of course...
jandrese · 3h ago
It got really bad when the BBS got all fancy and colorful with the ANSI graphics. Every character displayed might require 6 or 7 bytes down the wire to change the foreground and background color so your 2400 baud modem acted like a 300 baud modem or worse.
dkdbejwi383 · 12h ago
These tunnels are in the process of being turned into a spy-themed tourist attraction. I assume anything else of interest has been stripped out and scrapped by now.

https://www.architectsjournal.co.uk/news/wilkinsoneyres-220m...

thomasjb · 9h ago
This reminds me of a pet idea of mine, to write an interactive fiction / text-based dungeon crawler based around trying to navigate underground tunnels and interacting with various weird computers throughout them to progress (take the TTY from the seismometer and use it to access the ventilation control computer, find the datatape of the plans for level IX to then find the hydraulic controls for the main blast door ect.)
schlauerfox · 4h ago
Don't let dreams be dreams. Try a little work on it over time.
cjs_ac · 11h ago
In Kelvedon Hatch in Essex is the Secret Nuclear Bunker[0], which was first used as a RAF command post in the Second World War, but ended up as a Regional Government HQ for use in the event of a nuclear war. The room which was intended to be used for communication with surviving civil servants is filled with '80s microcomputers, and there's a manually operated telephone exchange (the automatic one having been removed when the bunker was decommissioned). The scariest part is probably the manikin of Margaret Thatcher in what would have been her private quarters.

[0] https://secretnuclearbunker.com/

mnw21cam · 5h ago
The road sign pointing to the Secret Nuclear Bunker is perhaps one of the more surreal road signs you'll see.
WalterBright · 3h ago
I gave away my Heathkit H11 (it's a PDP-11).

Always regretted that move. The person I gave it to threw it away. There's a picture of it on my twitter profile.

citizenfishy · 11h ago
Working in Post Office Research in the 1990's I watched a couple of PDP-11's being hoicked into a skip near our labs. Sadly I lived in a shared house with no room for them....
arethuza · 10h ago
At some point around '92 or '93 I was offered a Xerox lisp machine by the university I worked at - living in a small flat at the time I don't think I would have been popular if I had taken that home.
cjrp · 8h ago
Out of Adastral Park?
zkmon · 12h ago
Worked at a research institute which had a monitoring system for seismic activity that used PDP-11. Hardly ever knew how it worked, but the whole thing looked damn cool with circular tape drives and LEDs all over. Very unlike the bland rack servers of today (no circular stuff).
coldfireza · 12h ago
no updates in awhile sadly
roygbiv2 · 11h ago
Yeah I wonder where they are now.
vgb2k18 · 12h ago
> I'd point out of course that it appears that those folks are trespassing on private property - possibly in an environment that is quite unsafe. I hope nobody on here is daft enough to follow their lead.

Said the guy who proceeded to follow their lead. I get it he was a BT employee so may have not been trespassing, but he appeared to have a change of mind about the possibly quite unsafe environment.

bjord · 12h ago
it's clear in the thread that he got permission to do so

it's also reasonable to assume he had more information about the state of the location given his access as an employee, particularly given that it was a full two months before he actually retrieved them