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

I'm researching how businesses still rely on legacy DOS systems: dBase/Clipper/CLARION/Paradox or other DOS RAD environments on period hardware, CNC mills/spectrometers/microscopes controlled by ISA cards (bespoke or GPIB), and parallel port dongles. I want to hear your experiences, not to sell anything, but to explore an idea for keeping these running on modern hardware.

  1. freeli

    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 […]

  2. shakna

    dBase, MS-DOS 3.x, not using industrial anything. And as its a front of house tally machine, there's literally zero incentive to ever upgrade it. Downtime is measured in the yearly reboot, but there are non-operational business hours, so everything is just scheduled around that.

    We've already got it running on modern hardware. It's running under qemu. And the dBase stuff gets ripped out and sent to a REST server for broad monitoring and so on.

    We... Have one small oddity? There's a tape backup system, that throws everything through the soundcard. (Sound Blaster only.)

    Would be nice if onboarders didn't see dBase and just throw everything at AI instead of actually learning the skills they'll need when data migrations happen. But that's a people problem that can't be solved with tech.

  3. dazhbog

    I run 2 old Juki pick and place machines. They run DOS 6.22 on a 486 I think. My biggest pain points are, 1) booting them up without errors, and 2) transferring files to them wirelessly without any floppies. (without installing any DOS software)

    Closest I got was with a GOTEK and an ESP32 emulating a USB. But it was flaky so I dropped it for now.

  4. Felger

    Not DOS, but I sold a '99 HP computer running win98 last month, to replace an identical failed system. It was used to control a 50 meters long custom industrial paint booth line for special equipments (like 57" rims). Luckily, their HDD was OK. Urged them to make a few sector-to-sector copies of it on a few spare HDD. This $100 sell surely has prevented this business from massive bills or even going bankrupt in the meantime from production loss.

  5. EvanAnderson

    A Customer of mine has an 386 machine with an ISA interface board connected to an optical comparator instrument. I believe they also still have some MS-DOS-based computers connected to CNC machines, too.

    I have two Customers who use DOS applications under DOSBox (a Clipper-based accounting package at one, and a Symantec Q&A-based application at another).

  6. MarkSweep

    A company I used to work at still ships a piece of hardware with an Intel 186 microcontroller in it. The compilers are 16-bit DOS applications and the tool to program the DIP packages with the program was also a DOS application. I’m not sure what the physical interface between the programmer and computer was.

  7. londons_explore

    This thread reminds me that there is a huge benefit to using a super common OS+hardware.

    In 30 years time it will all be outdated... But emulators will exist and a business process in 2050 that still depended on something I built today could still run with minimal effort or risk.

  8. andix

    I had to keep an old clipper/dbase application running until recently. It worked perfectly seamless with vdos (vdos.info). It's commercial software, but very reasonably priced. Dosbox is another alternative, but didn't work as well with printing and I think also wasn't able to do row locking of dBASE databases over the network.

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2026-09-25