[HN Gopher] Melbourne Train Control System is running on a hardw...
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Melbourne Train Control System is running on a hardware emulated
PDP11
Author : SerCe
Score : 75 points
Date : 2024-12-26 11:17 UTC (3 days ago)
(HTM) web link (mastodon.sdf.org)
(TXT) w3m dump (mastodon.sdf.org)
| FireBeyond wrote:
| Almost 20 years ago I worked for a company that was bidding on
| replacing the CRTs that had been rendering platform train
| information, which was spat out as a stream from said PDP11. I
| even went to Flinders St and got to see it.
|
| It was everything you imagine a 70s era data stream to look like.
| 1200bps, weird control sequences, etc., etc. And no-one could
| really tell us much about it, but there was some poorly
| photocopied incomplete documentation.
| SulphurCrested wrote:
| I worked on this system during its development in the 1980s.
|
| There were actually two PDP-11s, the one to run the platform
| displays running locally-written software.
|
| The "weird control sequences" sent between the PDP-11 and the
| plaform displays were HDLC, a synchronous protocol then common
| in IBM token ring networks as SDLC. This was actually a decent
| technical solution because they only had to run one coax cable
| down each train line and the PIDS could sit there watching for
| their token slot. The hardware for HDLC would have been
| commodity, whereas fibre optic or carrier sense for long-run
| packet was not.
|
| The other PDP-11 that ran the signals (the "train describer")
| could plot the position of trains on glass TTY terminals using
| escape sequences (VT100, same as in xterm today) so our PDP-11
| pretended to be one of those and screen-scraped. So I was told,
| when I asked the guy who wrote it.
|
| All of that was done before I got there. I was called in with 6
| weeks to go before commissioning to fix the bit in the middle
| that recalculated train positions and arrival times.
| aryonoco wrote:
| As a Melburnian and a PDP-11 bits collector, this is just
| fantastic information!
|
| Do you have a blog or somewhere else where you share tidbits
| of information like this? Cause I sure would love to read
| that.
| skissane wrote:
| Apparently, this is no longer the case, and the old emulated
| PDP-11 system was replaced with a new system in 2014-2016:
| https://news.ycombinator.com/item?id=29157259
|
| The old system we are talking about here was Ericsson JZA 715,
| mostly written in Pascal with some parts in PDP-11 assembly,
| running under RSX-11M. Melbourne was the first site in the
| Southern Hemisphere for Ericsson's JZA series train control
| software, going live in 1982. JZA 715 first went live in Oslo in
| 1979. Earlier iterations of Ericsson's JZA software (JZA 410)
| went live in Stockholm in 1971 and Copenhagen in 1972.
| bobthepanda wrote:
| There is also an even newer CBTC system going into use for the
| new metro tunnel.
| rbanffy wrote:
| I wonder how much of that code is the old code compiled for
| the new platform.
| bobthepanda wrote:
| As part of the new system, I don't think very much at all,
| since the two technologies are fundamentally different;
| CBTC is trains talking directly to each other, and
| cab/wayside signalling is the tracks telling the trains
| what to do.
|
| That being said, it's pretty common in retrofits for the
| older system to still be around as a fallback if the CBTC
| fails.
| mrngm wrote:
| The toot itself is from 2021, and links to a 2012 PDF* from the
| "ASPECT 2012 Conference (UK)", specifically 2.10
| strangaric - legacy train control system stabilisation.pdf
|
| [*] Due to the website's interface, navigating directly to
| https://webinfo.uk/webdocssl/irse-kbase/ref-viewer.aspx?refn...
| seems to serve a web page that requires clicking through to
| request the PDF.
| avipars wrote:
| Wayback machine solved the problem for me
| https://web.archive.org/web/20221225231302/https://webinfo.u...
| retrac wrote:
| The largest nuclear power plant in North America, Darlington
| Nuclear Generating Station in Ontario, a bit east of Toronto,
| uses robots for handling the fuel rods. The plant was designed in
| the late 70s and the control software is apparently written in
| PDP-11 assembler. And they will keep using it for the remaining
| lifespan of the plant. So probably long after I retire and I'm
| not old. Now that's an idea for any young coders looking for a
| language that'll still be in use when they retire; they were
| hiring maintenance engineers to help keep it running a few years
| back. Maybe a bit of a dead end skills wise but some of it'll
| transfer to the embedded VAXen that still run half the assembly
| lines in the same region. (That career advice is sarcastic -
| probably.)
| rbanffy wrote:
| > That career advice is sarcastic - probably
|
| If you are into retrocomputing, they'll pay you to have fun
| doing archeology and necromancy. It's heaven.
| madaxe_again wrote:
| And so do several U.K. high street banks, written in COBOL for
| the PDP-11, run via an emulation layer of an AS/400, last I stuck
| my head into that particular hell, and I doubt much has changed.
| avipars wrote:
| Archive link:
| https://web.archive.org/web/20221225231302/https://webinfo.u...
| chasil wrote:
| We still run VAX VMS in production. Sometimes I run it on SimH.
|
| https://en.m.wikipedia.org/wiki/SIMH
|
| You can run it too.
|
| https://gunkies.org/wiki/Installing_VMS_V1.0_on_SIMH
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(page generated 2024-12-29 23:00 UTC)