9 ms·

Legacy Train Control System Stabilisation (2012) [pdf]

140 points by sohkamyung 5y ago

disposedtrolley 5y ago
This appears to be quite an old document (2012 judging by some of the dates in the screenshots, and the network map) but fascinating nonetheless, thanks for posting! I'd be interested in learning how the signalling tech has evolved over the years. There has always been a push by PTV (the government body responsible for public transport in Victoria) to establish a "turn up and go" timetable where trains depart often enough that you shouldn't need to plan ahead. One of the restrictions of the old signalling system was a fairly large minimum distance between trains that prevented frequent service. This caused some congestion, especially in the hub and spoke model of the Melbourne network where many lines converge to share tracks as they approach the CBD.
- jojobas 5y ago
  The signalling tech is old as mammoth's turd, "boomgates down/trains crawling" is a normal occurrence on quite a few lines.
- skissane 5y ago
  > This appears to be quite an old document (2012 judging by some of the dates in the screenshots, and the network map) but fascinating nonetheless, thanks for posting! Yeah, is this factoid - central Melbourne train signals being controlled by an emulated PDP-11 - still true in 2021? I don’t know. Definitely this is known to have been true some years ago but can anyone confirm if it remains true today? The construction of the Melbourne Metro requires new signals, which I assume would be controlled by a brand new control system not the old PDP-11-based system. But if you are going to introduce a new system for one line, wouldn’t it make sense to try to migrate the existing lines to it as well?
  - sytringy05 5y ago
    According to this web page - https://vicsig.net/infrastructure/signalbox/Metrol https://vicsig.net/infrastructure/signalbox/Metrol - it seems yes, it has been replaced. > Train Describer replaced with TCMS in 2014-2016.
- sytringy05 5y ago
  IIRC high speed signalling is coming with the Melbourne Metro trains (and the existing lines those trains will run through). Replacing train management systems like this with new ones seems to be all but impossible, my brother in law worked on one in the UK that was designed, built and implemented and the controllers basically said "no thanks". It only got implemented when they rebuilt the UI and control panels to look like the old one.
emmelaich 5y ago
I assumed it was software pdp11, but no, it is an "FPGA implementation of PDP-11" http://www.strobedata.com/home/ospreydx.html http://www.strobedata.com/home/ospreydx.html
- andrewl 5y ago
  Strobe Data's site reminds me of Berkshire Hathaway's: https://www.berkshirehathaway.com/ https://www.berkshirehathaway.com/ I think neither business needs to convince anybody of anything. If you need what Strobe is selling and can afford it, they probably made the sale.
  - foo92691 5y ago
    "Copyright © 1978-2021 Berkshire Hathaway Inc." Ok the web page looks old but maybe not that old
    - lukeh 5y ago
      Could be auto-generated.
    - zeckalpha 5y ago
      A subset of the content could be that old.
      - eesmith 5y ago
        The oldest I found was from 1977 - https://www.berkshirehathaway.com/letters/1977.html https://www.berkshirehathaway.com/letters/1977.html . Here's the 'Chairman's Letters To The Shareholders (Historical Compilation)' from the 1997 version of their site - https://web.archive.org/web/19970530212045/http://www.berkshirehathaway.com/letters/letters.htm https://web.archive.org/web/19970530212045/http://www.berksh... , with yearly publication.
- deleted 5y ago
  [deleted]
- 5y ago
userbinator 5y ago
As the old saying goes "don't fix it if it ain't broke"... but I wonder how long this new system will last. The PDP-11 ran for a few decades, but will the replacement outlast it?
- tus89 5y ago
  More like "who wants to change this code and cause a train crash?". Not I.
- EdwardDiego 5y ago
  There's a surprisingly large number of train systems using Kafka as a backbone. (Well, I consider it surprisingly large, as it's greater than zero.)
jakecopp 5y ago
Melbourne's new Metro tunnel (and Cranbourne, Pakenham and Sunbury lines) will use high capacity moving block signalling, with a minimum headway of 120 seconds!! [1] I assume this will be similar to the European Train Control System Level 3 [2] (which does not exist in a cross-vendor spec yet afaik) - it's being built by Rail Systems Alliance, a consortium made up of CPB Contractors, Alstom and Metro Trains Melbourne. [1]: https://bigbuild.vic.gov.au/projects/metro-tunnel/about/technology/high-capacity-signalling https://bigbuild.vic.gov.au/projects/metro-tunnel/about/tech... [2]: https://en.wikipedia.org/wiki/European_Train_Control_System https://en.wikipedia.org/wiki/European_Train_Control_System
- throwawaythekey 5y ago
  > [1]: https://bigbuild.vic.gov.au/projects/metro-tunnel/about/technology/high-capacity-signalling https://bigbuild.vic.gov.au/projects/metro-tunnel/about/tech... This video was great thanks! My naive assumption was that as trains operate in a relatively controlled environment a headway much smaller than 120s would've been easy to achieve. Cars regularly drive sub one second from each other! Is it just about minimizing the chance of catastrophe or is there more to it?
  - alfiedotwtf 5y ago
    Even though Melbourne trains are slow, I'd assume you'd want a long stopping distance and time for a train
  - jakecopp 5y ago
    Car stopping distances from 60mph/100kph are ~100 metres. 39,888 people died in the US in 2018 from car crashes. [1] Emergency braking distance of a TGV from 300 kmph (186 mph) is something like 3,500 m [2], carrying ~450 people. Moving block signalling systems take into account the current positions and velocities of both trains, and generate a maximum speed and braking curve. See [3] for the details, it's pretty fascinating systems design! [1]: https://en.wikipedia.org/wiki/List_of_countries_by_traffic-related_death_rate https://en.wikipedia.org/wiki/List_of_countries_by_traffic-r... [2]: https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/16334/1991_SAFETY%20RELEVANT%20OBSERVATIONS%20ON%20THE%20TGV%20HIGH%20SPEED.PDF https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/16... [3]: https://en.wikipedia.org/wiki/European_Train_Control_System https://en.wikipedia.org/wiki/European_Train_Control_System
Animats 5y ago
Due to the core software limitation (no source code available) Oh. So that's the real problem. They lost the source.
- mikewarot 5y ago
  Disassemblers have been around forever... recreating a working codebase that compiled to the same executable is definitely doable, however the fact that it runs a piece of infrastructure critical to the public makes the cost of being even one bit off unacceptable. This is the reason for going with emulation. Its a smaller change, and thus a smaller risk.
deleted 5y ago
[deleted]
grumblepeet 5y ago
More details in the linked PDF of the software used. https://webinfo.uk/webdocssl/irse-kbase/ref-viewer.aspx?refno=1559669757&document=2.10%20strangaric%20-%20legacy%20train%20control%20system%20stabilisation.pdf https://webinfo.uk/webdocssl/irse-kbase/ref-viewer.aspx?refn...
FireBeyond 5y ago
I know that a company I worked for bid for the platform information system to be revamped from old CRTs that would draw at 1200bps to show next train info across the system, and at that point, the PDP11 was still being used. I got to spend a few hours in there with it trying to debug a serial protocol that, again, was poorly documented, that was being used to render that information. "Not fun". Kinda glad we didn't get the contract.
1MachineElf 5y ago
Meanwhile, Sidney is eyeing quantum computing for their metro system: https://news.ycombinator.com/item?id=29139633 https://news.ycombinator.com/item?id=29139633
- nsonha 5y ago
  what on Earth could possibly be the logic behind this?
beachy 5y ago
> Due to the core software limitation (no source code available) we were compelled to integrate some original PDP-11 computer cards into the final product and this resulted in a hybrid PC platform. Amazing. I've never been anywhere that lost their source code. Would love to know how it happens.
- sushsjsuauahab 5y ago
  Breakdown of communication among key stakeholders, and nobody sufficiently motivated enough to stick their neck out :)
- sverhagen 5y ago
  I have been in two different situations many years ago, neither of which I take responsibility for, ha-ha: 1. Contractor relationship gone sour, turned out they had withheld source code from us. This lead to a dispute regarding the code ownership. Meanwhile we were running the corresponding binaries in the wild. We ended up reverse engineering the missing parts. 2. Source code is centrally managed on a server, hard disk failure, restore not working or backups wholly missing, don't remember. This was the pre-git era, probably Visual SourceSafe, which was entirely centralized. For me personally, let's just say I feasted my eyes and learned a lot. But I wager that there is still a lot of companies vulnerable in very similar ways today.
  - lagerstedt 5y ago
    Sourcesafe is a 90-era product. PDP-11 was discontinued long before Sourcesafe was even released. There were version control software around in the 70’s but I do not think that the adoption rate was very high. I think it’s reasonable to assume that they didn’t use it in this case.
    - eesmith 5y ago
      The SCCS paper (https://ieeexplore.ieee.org/document/6312866 https://ieeexplore.ieee.org/document/6312866 ) says the adoption rate at Bell Labs was high. > The Programmer's Workbench has proven to be very popular with both management and programmers, and is now used by almost all software projects at the author's installation. The followup paper https://dl.acm.org/doi/10.1145/800283.811111 https://dl.acm.org/doi/10.1145/800283.811111 at https://dl.acm.org/doi/pdf/10.1145/800283.811111 https://dl.acm.org/doi/pdf/10.1145/800283.811111 comments: > SCCS is used extensively within Bell Laboratories. For example, at one installation more than 3 million lines of source code are controlled with sccs. These 3 million lines represent 5000 files and the work of approximately 500 programmers. Additionally, sccs is used at many installations outside the Bell System.
ebanana 5y ago
if it aint broke
- themitigating 5y ago
  Wait until it does but by then you might not get replacement parts or the skills needed to fix the code might be rare.
shoo 5y ago
> The next challenge was the choice of the operating system for the host platform. We choose Windows XP because the Proprietary Co-processor card at the heart of the system was especially adapted to run under Windows XP. This operating system is not the best ‘choice for real time applications’ therefore special attention was required in the method of integration. Running the Windows operating system in cut down mode by disabling unnecessary apps and keeping it free of all ‘gadgets’ (Office software etc.) increased the system stability sufficiently > Due to the core software limitation (no source code available) we were compelled to integrate some original PDP-11 computer cards into the final product and this resulted in a hybrid PC platform. There are two very distinct hardware technologies in use in each complete system. The PC environment which is the host platform and the DEC environment which is the ‘legacy’ system. The connection is made using a proprietary Unibus adapter that links the Osprey co-processor to the short Unibus. This Unibus which is totally contained inside the special PC housing allows us to retain some key legacy DEC PDP-11 cards that in turn deceives the software ‘to think’ it is still running in a full DEC system in terms of timing. A marriage of ‘old’ and ‘new’ was borne One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.
- azalemeth 5y ago
  Am I the only one to whom the phrases "windows XP" and "trains" in the same sentence makes your blood chill a little? Also -- what about virtualizing the OS with pcie passthrough and being able to regularly snapshot it / migrate as running to other hosts (if they have enough odd cards, etc)
  - okl 5y ago
    I once worked on a project migrating a central component used on trains from Windows 95 to Windows XP... this year.
  - bluGill 5y ago
    XP had a solid base in NT. If you don't use the desktop it is very solid. I wouldn't connect it to the internet, but I wouldn't do that anyway .
niyaje 5y ago
this is not accurate/correct (anymore). there was a point in time when Melbourne was not "the worlds most livable city" and as such we have/had a train network from the 1950s, including the control systems which mostly ran up untill 2009 under connex' tenure post privatisation. Metro Trains which is a consortium took over the train network at this point and was contractually obligated by the state to upgrade all core and edge technology systems. I worked at MTM circa 2016/2017 and all the truly legacy operation control systems had been replaced. there was a heap of funding allocated for fun things like maintaining OCMS/IT systems and updating customer facing/passenger information systems.
- h0l0cube 5y ago
  Not sure how I missed this, but the comment on the mastodon post points this out too: > that emulated PDP-11 system was replaced in 2014-15 by an off-the-shelf “Westrol” system from vendor Invensys.
Sunspark 5y ago
You can still buy new physical PDP-11 CPUs from Russia.
- mikewarot 5y ago
  They're clones, not the original, and thus not likely to be exactly the same.
  - p_l 5y ago
    They aren't even clones, the surviving models are mostly compatible but independent implementations - of your system somehow manages to gain a dependency on undocumented quirk of a different CPU, they are unlikely to work.
- xvilka 5y ago
  A link, please?
  - Sunspark 5y ago
    KR1801VM2 (KP1801BM2) are on eBay. You won't be able to use them in a system at the current time though.
    - xvilka 5y ago
      Thank you! > You won't be able to use them in a system at the current time though. What do you mean? Why?
      - Sunspark 5y ago
        Well it's just the CPU. You still have to plug it in somewhere.
TMWNN 5y ago
Yet again I point to Vernor Vinge's A Deepness in the Sky, which describes in some detail the job position of programmer archaeologist (<https://en.wikipedia.org/wiki/Software_archaeology https://en.wikipedia.org/wiki/Software_archaeology>) thousands of years from now.
deleted 5y ago
[deleted]
varjag 5y ago
A legacy system you can't quite replace is called state of the art.
shoo 5y ago
Strobe Data Inc's list of customer success stories: http://www.strobedata.com/success/index.htm http://www.strobedata.com/success/index.htm
- p_l 5y ago
  Some success stories have interesting language :D > Valuing Navy personnel highly, the Navy elected to field test with one contractor and nine Marines.
thisrod 5y ago
People say that the Melbourne city loop was the world's first computerized train line. If that's true, this hardware and software had some serious heritage value. It's a pity that Museums Victoria didn't try harder to preserve it when these replacements were made.
- skissane 5y ago
  > People say that the Melbourne city loop was the world's first computerized train line. If that's true, I don't believe that is true. The Melbourne city loop was using the Ericsson JZA 715 system. According to page 9 of [0], Melbourne's implementation of JZA 715 went live in 1982, but Oslo's JZA 715 implementation went live in 1979. Furthermore, JZA 715 was an evolution of earlier Ericsson computer-based rail traffic control systems, going back to the JZA 410 which went live in Stockholm in 1971 and Copenhagen in 1972. So, if these Ericsson systems were in any sense a "world-first" (don't know enough about the history of this technology to say), it looks like the "world-first" happened in Scandinavia, and Melbourne may have simply been "Australia-first" (or "Southern Hemisphere-first" or maybe even "not-Scandinavia-first") [0] https://www.jonroma.net/media/signaling/articles/ericsson/L.%20M.%20Ericsson%20Review.%20Control%20and%20Supervision%20System%20for%20Railway%20Traffic.%20Von%20Linde%2C%20Otto%20Berg.%201982.pdf https://www.jonroma.net/media/signaling/articles/ericsson/L....
yangkuki 5y ago
this is awesome, try it out! https://word-unscrambler.io https://word-unscrambler.io
spacehunt 5y ago
> Dark territories where there is no remote control or indications feeding back to Metrol and Voice Communication is the only means of control. I did not realise just how much of the network is Dark -- for instance, everything beyond _Burnley_ (just 3 stations away from Flinders St) is Dark!

140 points by sohkamyung 5y ago

This appears to be quite an old document (2012 judging by some of the dates in the screenshots, and the network map) but fascinating nonetheless, thanks for posting! I'd be interested in learning how the signalling tech has evolved over the years. There has always been a push by PTV (the government body responsible for public transport in Victoria) to establish a "turn up and go" timetable where trains depart often enough that you shouldn't need to plan ahead. One of the restrictions of the old signalling system was a fairly large minimum distance between trains that prevented frequent service. This caused some congestion, especially in the hub and spoke model of the Melbourne network where many lines converge to share tracks as they approach the CBD.

jojobas 5y ago
The signalling tech is old as mammoth's turd, "boomgates down/trains crawling" is a normal occurrence on quite a few lines.
skissane 5y ago
> This appears to be quite an old document (2012 judging by some of the dates in the screenshots, and the network map) but fascinating nonetheless, thanks for posting! Yeah, is this factoid - central Melbourne train signals being controlled by an emulated PDP-11 - still true in 2021? I don’t know. Definitely this is known to have been true some years ago but can anyone confirm if it remains true today? The construction of the Melbourne Metro requires new signals, which I assume would be controlled by a brand new control system not the old PDP-11-based system. But if you are going to introduce a new system for one line, wouldn’t it make sense to try to migrate the existing lines to it as well?
- sytringy05 5y ago
  According to this web page - https://vicsig.net/infrastructure/signalbox/Metrol https://vicsig.net/infrastructure/signalbox/Metrol - it seems yes, it has been replaced. > Train Describer replaced with TCMS in 2014-2016.
sytringy05 5y ago
IIRC high speed signalling is coming with the Melbourne Metro trains (and the existing lines those trains will run through). Replacing train management systems like this with new ones seems to be all but impossible, my brother in law worked on one in the UK that was designed, built and implemented and the controllers basically said "no thanks". It only got implemented when they rebuilt the UI and control panels to look like the old one.

emmelaich 5y ago

I assumed it was software pdp11, but no, it is an "FPGA implementation of PDP-11" http://www.strobedata.com/home/ospreydx.html http://www.strobedata.com/home/ospreydx.html

andrewl 5y ago
Strobe Data's site reminds me of Berkshire Hathaway's: https://www.berkshirehathaway.com/ https://www.berkshirehathaway.com/ I think neither business needs to convince anybody of anything. If you need what Strobe is selling and can afford it, they probably made the sale.
- foo92691 5y ago
  "Copyright © 1978-2021 Berkshire Hathaway Inc." Ok the web page looks old but maybe not that old
  - lukeh 5y ago
    Could be auto-generated.
  - zeckalpha 5y ago
    A subset of the content could be that old.
    - eesmith 5y ago
      The oldest I found was from 1977 - https://www.berkshirehathaway.com/letters/1977.html https://www.berkshirehathaway.com/letters/1977.html . Here's the 'Chairman's Letters To The Shareholders (Historical Compilation)' from the 1997 version of their site - https://web.archive.org/web/19970530212045/http://www.berkshirehathaway.com/letters/letters.htm https://web.archive.org/web/19970530212045/http://www.berksh... , with yearly publication.
deleted 5y ago
[deleted]
5y ago

userbinator 5y ago

As the old saying goes "don't fix it if it ain't broke"... but I wonder how long this new system will last. The PDP-11 ran for a few decades, but will the replacement outlast it?

tus89 5y ago
More like "who wants to change this code and cause a train crash?". Not I.
EdwardDiego 5y ago
There's a surprisingly large number of train systems using Kafka as a backbone. (Well, I consider it surprisingly large, as it's greater than zero.)

jakecopp 5y ago

Melbourne's new Metro tunnel (and Cranbourne, Pakenham and Sunbury lines) will use high capacity moving block signalling, with a minimum headway of 120 seconds!! [1] I assume this will be similar to the European Train Control System Level 3 [2] (which does not exist in a cross-vendor spec yet afaik) - it's being built by Rail Systems Alliance, a consortium made up of CPB Contractors, Alstom and Metro Trains Melbourne. [1]: https://bigbuild.vic.gov.au/projects/metro-tunnel/about/technology/high-capacity-signalling https://bigbuild.vic.gov.au/projects/metro-tunnel/about/tech... [2]: https://en.wikipedia.org/wiki/European_Train_Control_System https://en.wikipedia.org/wiki/European_Train_Control_System

throwawaythekey 5y ago
> [1]: https://bigbuild.vic.gov.au/projects/metro-tunnel/about/technology/high-capacity-signalling https://bigbuild.vic.gov.au/projects/metro-tunnel/about/tech... This video was great thanks! My naive assumption was that as trains operate in a relatively controlled environment a headway much smaller than 120s would've been easy to achieve. Cars regularly drive sub one second from each other! Is it just about minimizing the chance of catastrophe or is there more to it?
- alfiedotwtf 5y ago
  Even though Melbourne trains are slow, I'd assume you'd want a long stopping distance and time for a train
- jakecopp 5y ago
  Car stopping distances from 60mph/100kph are ~100 metres. 39,888 people died in the US in 2018 from car crashes. [1] Emergency braking distance of a TGV from 300 kmph (186 mph) is something like 3,500 m [2], carrying ~450 people. Moving block signalling systems take into account the current positions and velocities of both trains, and generate a maximum speed and braking curve. See [3] for the details, it's pretty fascinating systems design! [1]: https://en.wikipedia.org/wiki/List_of_countries_by_traffic-related_death_rate https://en.wikipedia.org/wiki/List_of_countries_by_traffic-r... [2]: https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/16334/1991_SAFETY%20RELEVANT%20OBSERVATIONS%20ON%20THE%20TGV%20HIGH%20SPEED.PDF https://railroads.dot.gov/sites/fra.dot.gov/files/fra_net/16... [3]: https://en.wikipedia.org/wiki/European_Train_Control_System https://en.wikipedia.org/wiki/European_Train_Control_System

Animats 5y ago

Due to the core software limitation (no source code available) Oh. So that's the real problem. They lost the source.

mikewarot 5y ago
Disassemblers have been around forever... recreating a working codebase that compiled to the same executable is definitely doable, however the fact that it runs a piece of infrastructure critical to the public makes the cost of being even one bit off unacceptable. This is the reason for going with emulation. Its a smaller change, and thus a smaller risk.

deleted 5y ago

[deleted]

grumblepeet 5y ago

More details in the linked PDF of the software used. https://webinfo.uk/webdocssl/irse-kbase/ref-viewer.aspx?refno=1559669757&document=2.10%20strangaric%20-%20legacy%20train%20control%20system%20stabilisation.pdf https://webinfo.uk/webdocssl/irse-kbase/ref-viewer.aspx?refn...

FireBeyond 5y ago

I know that a company I worked for bid for the platform information system to be revamped from old CRTs that would draw at 1200bps to show next train info across the system, and at that point, the PDP11 was still being used. I got to spend a few hours in there with it trying to debug a serial protocol that, again, was poorly documented, that was being used to render that information. "Not fun". Kinda glad we didn't get the contract.

1MachineElf 5y ago

Meanwhile, Sidney is eyeing quantum computing for their metro system: https://news.ycombinator.com/item?id=29139633 https://news.ycombinator.com/item?id=29139633

nsonha 5y ago
what on Earth could possibly be the logic behind this?

beachy 5y ago

> Due to the core software limitation (no source code available) we were compelled to integrate some original PDP-11 computer cards into the final product and this resulted in a hybrid PC platform. Amazing. I've never been anywhere that lost their source code. Would love to know how it happens.

sushsjsuauahab 5y ago
Breakdown of communication among key stakeholders, and nobody sufficiently motivated enough to stick their neck out :)
sverhagen 5y ago
I have been in two different situations many years ago, neither of which I take responsibility for, ha-ha: 1. Contractor relationship gone sour, turned out they had withheld source code from us. This lead to a dispute regarding the code ownership. Meanwhile we were running the corresponding binaries in the wild. We ended up reverse engineering the missing parts. 2. Source code is centrally managed on a server, hard disk failure, restore not working or backups wholly missing, don't remember. This was the pre-git era, probably Visual SourceSafe, which was entirely centralized. For me personally, let's just say I feasted my eyes and learned a lot. But I wager that there is still a lot of companies vulnerable in very similar ways today.
- lagerstedt 5y ago
  Sourcesafe is a 90-era product. PDP-11 was discontinued long before Sourcesafe was even released. There were version control software around in the 70’s but I do not think that the adoption rate was very high. I think it’s reasonable to assume that they didn’t use it in this case.
  - eesmith 5y ago
    The SCCS paper (https://ieeexplore.ieee.org/document/6312866 https://ieeexplore.ieee.org/document/6312866 ) says the adoption rate at Bell Labs was high. > The Programmer's Workbench has proven to be very popular with both management and programmers, and is now used by almost all software projects at the author's installation. The followup paper https://dl.acm.org/doi/10.1145/800283.811111 https://dl.acm.org/doi/10.1145/800283.811111 at https://dl.acm.org/doi/pdf/10.1145/800283.811111 https://dl.acm.org/doi/pdf/10.1145/800283.811111 comments: > SCCS is used extensively within Bell Laboratories. For example, at one installation more than 3 million lines of source code are controlled with sccs. These 3 million lines represent 5000 files and the work of approximately 500 programmers. Additionally, sccs is used at many installations outside the Bell System.

ebanana 5y ago

if it aint broke

themitigating 5y ago
Wait until it does but by then you might not get replacement parts or the skills needed to fix the code might be rare.

shoo 5y ago

> The next challenge was the choice of the operating system for the host platform. We choose Windows XP because the Proprietary Co-processor card at the heart of the system was especially adapted to run under Windows XP. This operating system is not the best ‘choice for real time applications’ therefore special attention was required in the method of integration. Running the Windows operating system in cut down mode by disabling unnecessary apps and keeping it free of all ‘gadgets’ (Office software etc.) increased the system stability sufficiently > Due to the core software limitation (no source code available) we were compelled to integrate some original PDP-11 computer cards into the final product and this resulted in a hybrid PC platform. There are two very distinct hardware technologies in use in each complete system. The PC environment which is the host platform and the DEC environment which is the ‘legacy’ system. The connection is made using a proprietary Unibus adapter that links the Osprey co-processor to the short Unibus. This Unibus which is totally contained inside the special PC housing allows us to retain some key legacy DEC PDP-11 cards that in turn deceives the software ‘to think’ it is still running in a full DEC system in terms of timing. A marriage of ‘old’ and ‘new’ was borne One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.

azalemeth 5y ago
Am I the only one to whom the phrases "windows XP" and "trains" in the same sentence makes your blood chill a little? Also -- what about virtualizing the OS with pcie passthrough and being able to regularly snapshot it / migrate as running to other hosts (if they have enough odd cards, etc)
- okl 5y ago
  I once worked on a project migrating a central component used on trains from Windows 95 to Windows XP... this year.
- bluGill 5y ago
  XP had a solid base in NT. If you don't use the desktop it is very solid. I wouldn't connect it to the internet, but I wouldn't do that anyway .

niyaje 5y ago

this is not accurate/correct (anymore). there was a point in time when Melbourne was not "the worlds most livable city" and as such we have/had a train network from the 1950s, including the control systems which mostly ran up untill 2009 under connex' tenure post privatisation. Metro Trains which is a consortium took over the train network at this point and was contractually obligated by the state to upgrade all core and edge technology systems. I worked at MTM circa 2016/2017 and all the truly legacy operation control systems had been replaced. there was a heap of funding allocated for fun things like maintaining OCMS/IT systems and updating customer facing/passenger information systems.

h0l0cube 5y ago
Not sure how I missed this, but the comment on the mastodon post points this out too: > that emulated PDP-11 system was replaced in 2014-15 by an off-the-shelf “Westrol” system from vendor Invensys.

Sunspark 5y ago

You can still buy new physical PDP-11 CPUs from Russia.

mikewarot 5y ago
They're clones, not the original, and thus not likely to be exactly the same.
- p_l 5y ago
  They aren't even clones, the surviving models are mostly compatible but independent implementations - of your system somehow manages to gain a dependency on undocumented quirk of a different CPU, they are unlikely to work.
xvilka 5y ago
A link, please?
- Sunspark 5y ago
  KR1801VM2 (KP1801BM2) are on eBay. You won't be able to use them in a system at the current time though.
  - xvilka 5y ago
    Thank you! > You won't be able to use them in a system at the current time though. What do you mean? Why?
    - Sunspark 5y ago
      Well it's just the CPU. You still have to plug it in somewhere.

TMWNN 5y ago

Yet again I point to Vernor Vinge's A Deepness in the Sky, which describes in some detail the job position of programmer archaeologist (<https://en.wikipedia.org/wiki/Software_archaeology https://en.wikipedia.org/wiki/Software_archaeology>) thousands of years from now.

deleted 5y ago

[deleted]

varjag 5y ago

A legacy system you can't quite replace is called state of the art.

shoo 5y ago

Strobe Data Inc's list of customer success stories: http://www.strobedata.com/success/index.htm http://www.strobedata.com/success/index.htm

p_l 5y ago
Some success stories have interesting language :D > Valuing Navy personnel highly, the Navy elected to field test with one contractor and nine Marines.

thisrod 5y ago

People say that the Melbourne city loop was the world's first computerized train line. If that's true, this hardware and software had some serious heritage value. It's a pity that Museums Victoria didn't try harder to preserve it when these replacements were made.

skissane 5y ago
> People say that the Melbourne city loop was the world's first computerized train line. If that's true, I don't believe that is true. The Melbourne city loop was using the Ericsson JZA 715 system. According to page 9 of [0], Melbourne's implementation of JZA 715 went live in 1982, but Oslo's JZA 715 implementation went live in 1979. Furthermore, JZA 715 was an evolution of earlier Ericsson computer-based rail traffic control systems, going back to the JZA 410 which went live in Stockholm in 1971 and Copenhagen in 1972. So, if these Ericsson systems were in any sense a "world-first" (don't know enough about the history of this technology to say), it looks like the "world-first" happened in Scandinavia, and Melbourne may have simply been "Australia-first" (or "Southern Hemisphere-first" or maybe even "not-Scandinavia-first") [0] https://www.jonroma.net/media/signaling/articles/ericsson/L.%20M.%20Ericsson%20Review.%20Control%20and%20Supervision%20System%20for%20Railway%20Traffic.%20Von%20Linde%2C%20Otto%20Berg.%201982.pdf https://www.jonroma.net/media/signaling/articles/ericsson/L....

yangkuki 5y ago

this is awesome, try it out! https://word-unscrambler.io https://word-unscrambler.io

spacehunt 5y ago

> Dark territories where there is no remote control or indications feeding back to Metrol and Voice Communication is the only means of control. I did not realise just how much of the network is Dark -- for instance, everything beyond _Burnley_ (just 3 stations away from Flinders St) is Dark!