Thread

Ask HN: Who's still keeping a DOS machine up because the business depends on it?

297 points · 304 comments · mlaux

freeli · 1790375986 · focus · HN ↗
A certain nuclear power plant had a Windows NT 4.0 machine running as late as 2007. The reason is interesting.
The machine's purpose was to report status of the control rods that mitigate nuclear reactions. Basically, "are the rods inserted, and if so, how many / how far?". I want to emphasize that this was reporting only, NOT control.
The original software was written back in the 80's, when the plant was originally commissioned, for AmigaOS. Of course, it's hard to buy Amigas anymore, and the original one died long ago (nobody remembers when).
So in the mid '90s, the utility purchased an AmigaOS emulator that ran on Windows NT 4.0, which was current at the time. The emulator (IIRC) was developed by a firm in the UK. The firm went out of business sometime in the late '90s. The control rod monitoring software ran under this emulator on top of NT4.
Windows NT 4.0 was the last OS to allow the emulation software direct access to the physical hardware that produced the status signal. Later versions of Windows abstracted the hardware access away, and the monitoring software broke. Because the emulation company had gone belly up, there was no way to fix the incompatibility.
So the utility had a choice: get new hardware/software certified (by NRC?), or keep doing what they were doing with the software (and hardware) that they had. They chose the latter.
So this is how, in 2007, during a tour of the facility, I stumbled across a Pentium 1 system running an AmigaOS emulator on Windows NT 4.0 that was responsible for displaying the status of the control rods of a nuclear power plant.
Spare hardware for this setup was purchased off of eBay and stocked on an adjacent shelf.
1. Froedlich · 1790382795 · focus · HN ↗
  A friend works for an airline as a flight simulator tech. Their entire software stack, including the compiler and OS, is FAA-certified.
  Then their ancient Honeywell(?) mainframes reached end-of-life they scouted for compatible hardware, of which there was none. The cost of certifying new software, plus the time involved, was astronomical. So, after consulting with the FAA, they paid a hardware company to clone the ancient mainframes in modern silicon. The FAA signed off on it, and they had all-new computers - much smaller than the originals - running the old stack.
  1. zx8080 · 1790384009 · focus · HN ↗
    It's _very_ hard to believe some company to simply "clone the mainframe" into chip. Mind sharing any link to this effort?
    vincent-manis · 1790386893 · focus · HN ↗
    When Xerox established PARC, they asked the assembled scientists what computer they wanted. The majority view was a DEC PDP-10 KA10, with the BBN memory management unit that let it run Tenex (the ancestor of DEC TOPS-20). Xerox couldn't really buy a competitor's mainframe, so they built MAXC (maximum access computer), which was a complete emulation of the Tenex machines.
    zem · 1790415458 · focus · HN ↗
    very apt that xerox parc was full of tenex engineers!
    fsckboy · 1790440994 · focus · HN ↗
    >MAXC (maximum access computer), which was a complete emulation of the Tenex machines.
    Compuserve also had a software dependency on the PDP-10 and Decsystem 20, and when those machines were no longer available they bought a company making clones so they could continue to manufacture them for themselves. The company they bought, Microsolutions, was Mark Cuban's first startup.
    making clones of mainframes (IBM's) had been a big area of intellectual property litigation, but also facing monopolization investigations, IBM had to allow them. They were referred to as "plug compatibles".
    FrankWilhoit · 1790601625 · focus · HN ↗
    The clone hardware manufacturer was Systems Concepts. Microsolutions was a software play -- I think they had something to do with trying to port 1022/1032.
    znpy · 1790415261 · focus · HN ↗
    Meh, old architectures are relatively simple and you can get 95% of those via fpga softcores (some freely available, some paid) and run them on fpga. The rest can be implemented by a proper ee team.
    theodric · 1790417421 · focus · HN ↗
    I mean...there's some precedent. The XKL TOAD ("Ten On A Desk") implements the PDP-10 instruction set, and will happily run TOPS-10/TOPS-20. LCM had one doing just that.
    <a href="https://www.computerhistory.org/collections/catalog/102773832/" rel="nofollow">https://www.computerhistory.org/collections/catalog/10277383... <a href="https://www.twenex.org/?network" rel="nofollow">https://www.twenex.org/?network
    hapless · 1790448453 · focus · HN ↗
    XKL is still in business (<a href="https://xkl.com/" rel="nofollow">https://xkl.com/)
    as far as i know the control plane on their equipment is still a pdp-10 compatible
    DonHopkins · 1790461747 · focus · HN ↗
    It's tempting to write a PDP-10 emulator for the Atari ST called TOAST.
    FWIW I'm developing "tiny-titan", a stand-in for Cambridge's Titan mainframe that talks to Heinz Lemke's 1972 PIXIE program over an emulated version of Neil Wiseman's PDP-7 <=> Titan link. It doesn't emulate Titan itself, just the conversation PIXIE had with it, so the unmodified 1972 PDP-7 code dials home and uploads its drawings.
    <a href="https://en.wikipedia.org/wiki/Titan_(1963_computer)" rel="nofollow">https://en.wikipedia.org/wiki/Titan_(1963_computer)
    >Titan was the prototype of the Atlas 2 computer developed by Ferranti and the University of Cambridge Mathematical Laboratory in Cambridge, England. It was designed starting in 1963, and in operation from 1964 to 1973.
    <a href="https://news.ycombinator.com/item?id=49407938">https://news.ycombinator.com/item?id=49407938
    <a href="https://news.ycombinator.com/item?id=40617894">https://news.ycombinator.com/item?id=40617894
    Flight of the PIXIE - Yuja Wang:
    <a href="https://www.youtube.com/watch?v=jDrqR9XssJI" rel="nofollow">https://www.youtube.com/watch?v=jDrqR9XssJI
    UNIVERSITY MATHEMATICAL LABORATORY, CAMBRIDGE: Cambridge Supervisor - Planning Document 10 Software for the Titan/PDP-7 link:
    <a href="https://cucps.soc.srcf.net/titan/supplan/pd10.htm" rel="nofollow">https://cucps.soc.srcf.net/titan/supplan/pd10.htm
    Here is a photo of Heinz Lemke operating PIXIE with the light pen and 340 display on the PDP-7 (also seen in the video above):
    <a href="https://www.facebook.com/groups/779220482206901/posts/6297725037023057/" rel="nofollow">https://www.facebook.com/groups/779220482206901/posts/629772...
    theodric · 1790542226 · focus · HN ↗
    Fascinating stuff; thank you for sharing. Can I follow your work somewhere??
    DonHopkins · 1790808630 · focus · HN ↗
    Thanks! I'm in the process of bailing from Medium, and I'm moving my stuff to a reimplemention of HyperTIES, the hypermedia browser I developed for NeWS in 1987-1990 at the University of Maryland Human Computer Interaction Lab, and I'm dogfooding it to publish all my other stuff:
    <a href="https://hyperties.org" rel="nofollow">https://hyperties.org
    Ostensibly the site is about HyperTIES itself, but I'm publishing other stuff there too like a PDP-7 emulator!
    <a href="https://hyperties.org/databases/pixie/pixie-live/" rel="nofollow">https://hyperties.org/databases/pixie/pixie-live/
    Here's a part of the demo I was giving at EduCom in October 1988 at the Sun booth on the trade show floor, across from the NeXT booth, where Steve Jobs and Bill Joy came by. Because he had shaved his beard, I didn't realize it was Bill Joy when I was showing him a demo of his head popping up! He took it pretty well though, better than Jobs.
    <a href="https://hyperties.org/databases/playground/sun-founders-big-heads/" rel="nofollow">https://hyperties.org/databases/playground/sun-founders-big-...
    Here's a paper looking back at HyperTIES:
    <a href="https://hyperties.org/databases/hyperties/a-look-back/" rel="nofollow">https://hyperties.org/databases/hyperties/a-look-back/
    anthk · 1790534233 · focus · HN ↗
    I'd happily run ITS on that.
    mitxela · 1790419194 · focus · HN ↗
    Custom chips aren't as expensive as you think. About a few million dollars for the design and a hundred thousand chips, way out of reach for a hobbyist, but accessible to large enough companies. Just because it's opaque to us software people doesn't mean it's not a real industry you can buy things from.
    realo · 1790426984 · focus · HN ↗
    And all that expensive engineering is still less costly AND faster (!!) than a new software certification.
    Cannot refrain myself from asking why ...
    ianjbutler · 1790428193 · focus · HN ↗
    Situation: Software-1 on Platform-1, both certified.
    Time-evolution: P1 is deprecated, replaced by uncertified P2, but S1 remains certified.. just nowhere certified to run yet.
    Solution: There's another software S2 which originally vouched for P1, itself still certified, which can still be used to certify P2.
    Counterfactual?: If S1 were deprecated in favor of new S3.. there'd be no plan to certify it!
    The problem: None of this actually makes any sense! But we're trying to fake due diligence. Everyone knows the hardware/platforms kinda need to be certified with respect to each other anyway, but if we did it that way it would all be even more expensive an time-consuming.
    mitxela · 1790429547 · focus · HN ↗
    Doesn't seem crazy to me. Which one do you suppose needs more proof of correctness: a cake recipe, or the oven you bake the cake in? The recipe has to be correct or the cake won't work, but the oven just has to hold a temperature.
    realo · 1790435761 · focus · HN ↗
    That "just" is quite the load-bearing seam ...
    Particularly when the task here is "just" to measure some rod positions in a constrained 3D space ...
    starky · 1790440520 · focus · HN ↗
    Ovens vary greatly. There is no consistency in how even the heat is in the space, the airflow through the space, how much and how fast the temperature varies around the set temperature, etc. These things all do affect how things bake up and often people have to tweak recipes for their specific oven.
    In a case where something is safety critical the computer is super important as very subtle errors could cause catastrophic consequences. This is why you get into things like running software on 3+ computers concurrently depending on how fail-safe something has to be.
    flyinghamster · 1790430809 · focus · HN ↗
    It could be an FPGA. Given enough gates, and the know-how to program them, you can make an FPGA emulate anything. Speed and efficiency could be better or worse, but if you're targeting old hardware, better is likely.
    jasomill · 1790467993 · focus · HN ↗
    IBM released the PC XT/370[1], built around a pair of 68000s and an 8087 with custom microcode to emulate System/370 instructions, in 1983.
    It's not hard to imagine a similar system fabricated around an open or licensed processor core today being well within the budget of a major airline today.
    Software emulation would no doubt be less expensive, but there could have been regulatory reasons for building plug-compatible hardware.
    [1] <a href="https://en.wikipedia.org/wiki/PC-based_IBM_mainframe-compatible_systems#Personal_Computer_XT/370" rel="nofollow">https://en.wikipedia.org/wiki/PC-based_IBM_mainframe-compati...

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