Thread

1. 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. throwaway2037 · 1790419792 · focus · HN ↗

      This is a great post. How does someone write software that needs to run for ~50 years where the hardware will need to be replaced with non-equivalent, newer hardware? If I were facing this issue today, I might start with an OS that has excellent emulation. Example: Can I run 32-bit MS Windows 95 via emulation on a variety of current 64-bit OSes, like MS Windows, Linux, AIX, HP-UX, etc. If yes, then we can assume(?) this emulation will remain relatively stable even if we upgrade our hardware later. Maybe I am overthinking the whole problem: Can VMs do exactly what I want today? Will VMs running ancient OSes, such as 32-bit MS Windows 95, continue to be stable/viable in the future? I am unsure.

      1. jl6 · 1790424085 · focus · HN ↗

         > How does someone write software that needs to run for ~50 years where the hardware will need to be replaced with non-equivalent, newer hardware?

         Some ideas:

         Write it in a popular language/ecosystem, stick rigidly to well-defined APIs, use commodity hardware, flatten out any malignant cleverness, maintain documentation on why every part does the thing it does, and make the source code readily available.

         This is based on working with some very old systems, and each point above is the opposite of something that made life harder.

         1. inopinatus · 1790435665 · focus · HN ↗

            Unfortunately, “popular language/ecosystem” includes JavaScript and PHP.

            I’d go for “universal and timeless”, which has meant C for several decades now. There is, I’d concede, a reasonable chance that Rust obtains that label in our lifetimes.

            1. cozzyd · 1790448086 · focus · HN ↗

               And worse for posterity, Python
            2. asa400 · 1790450368 · focus · HN ↗

               Yeah agreed. Popular is a good first approximation, but to be more precise I think you want tools where the incentives in the community reward stability over features that require breakage, which would include languages and runtimes like Erlang and Clojure.

               Neither is popular when compared to for example Python or PHP, but they both have cultures that care about stability in the core runtime and the libraries. Most folks probably don’t know that about Erlang and maybe think it’s some new whiz-bang thing, but Erlang is incredibly stable and well supported by a dedicated team that has been doing it for years and years at this point. I don’t know if Erlang will be more or less popular in 20 years but it 100% will be around and be receiving updates, I would put money on it.

            3. very-old-sw · 1790474967 · focus · HN ↗

               My C programs from a few decades ago, before namespaces were invented, no longer compile. However, the old executables still execute. The old C compilers are available but not supported; ChatGPT warns to expect trouble. Perhaps maybe there are compatibility switches that work correctly. Using them would require changing the makefiles.

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