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

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.

I wouldn't call them business-critical computers, but I do have about 3-4 computers under one of my workbenches dedicated to certain work I did for a client. One of them has an EPROM programmer set-up, which includes a custom ISA-card, and a ribbon cable to an external box with a ZIF-socket. The software for that requires MS-DOS. To network that box, which is a 486SX, I run WFWG 3.11. Since these never go on the enternet or anything outside 'the lab', I don't worry about the old MS networking.

A second computer has an MS-DOS program that captures data input on a pair of RS-422 ports (two more special ISA cards) That let me look at packet data at a low level and watch which serial port received what data, and track character-level handshaking of a proprietary protocol.

A third computer under Windows 2000 ran a 68HC11 cross-compiler that didn't require a dongle. I also used this to run a remote debugger that allowed me to single-step through the 68HC11 code running on the target but moved to the target's RAM. To do this 'properly' I was constantly generating hard-copies from the compiler which would show me the C-code, and the resulting assembler code that I'd track through the debugger. I used a lot of paper on a project sometimes.

A fourth computer with MS-DOS, with WFWG3.11 also installed on it, had all my old CAD programs on it, from before they required dongles, so that I could pull-up drawings of some of the hardware I designed. Some of those were finicky about which mouse I use. I still have an old Logitech mouse C7 that two of my CAD programs required.

I was working on a replacement platform that put this into an Atmel-based controller, shipped a couple of samples, then went blind in one eye, while my client had a stroke and was out of action for a year. Between both of our health problems, that project kind of died.

[Source: Was NT developer - have code in NT 4.0...]

The big problem will almost always be some hardware dependency that breaks, almost always in I/O. I've seen video software used by TV producers that depended on an ISA (not EISA nor PCI, ISA) card to read NTSC input and impose text over it. And it broke as they were getting ready to add commentary to a live broadcast of a race (which I was driving in.)

The world is full of machine tools and metrology devices that are stuck on some ancient computer/software because they made a weird proprietary protocol over the top of a centronics connector, or some other "WHAT were they thinking??" construction...

All of these could be overcome with a new I/O device, and/or writing a device driver. So using say a raspberry PI that talks ethernet to your "monitor" PC is probably relatively change proof.

If there is any documentation, if anybody can find said docs, if there's budget for a new I/O card and the device driver to go with it. Often the parties who have those resources would rather sell you a new machine tool, metrology machine, or I suppose, nuclear reactor (:-)

Of course, certification is a big deal... A particular certification structure led to the 737 MAX tragedies. And since certifying authorities don't always have detailed tech knowledge of what things are, they have a hard time saying "no, you can't slide that by, you have to build and certify a new thing".

Not MSDOS, but I feel obliged to shared the story of an auto shop in Poland using a Commodore 64 to run the calibration and wheel balancing some years back. It was viral news at the time but worth sharing again.

https://www.youtube.com/watch?v=tXdLtnt-nvE

Original Polish article - https://www.trojmiasto.pl/wiadomosci/Warszatat-samochodowy-z...

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.

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.

Not any longer. Back in the mid-2000s the company I worked for sold point-of-sale systems based upon a multi-user 4GL application (TAS Pro). Similar to dBase/Clipper etc., using the Novell Btrieve ISAM database engine.

With the advent of USB and SATA we ceased to be able to source industrial embedded x86 boards which could run the application. At the time this was with Novell DR-DOS, which was relatively modern in terms of hardware support but still behind the times and we were struggling to manufacture new systems. The company was very small, so a full rewrite was investigated--I did a prototype using PostgreSQL and Gtkmm--but it wasn't realistic. Today, an AI could probably do a full rewrite in a day or two, including migration tooling. Back then, it would have been a multi-year effort for one person given the application's size and complexity.

My solution was to run Linux since it had full support for the hardware. Debian Sarge at the time. This used a Perl frontend and dialog(1) to present a simple menu system at startup. This did backups, software updates (over dialup!), remote access for support (again over dialup), ran backups and ran the main application. It would start DOSEMU which provided the application with VGA display, COM ports and parallel ports for the application to drive "directly" (from its perspective). It also used Samba and CUPS to provide the DOS environment with shared network drives with exclusive byte-range file locking needed for the multi-user network database to work with concurrent users without data corruption, and also multi-user report printing and receipt printing.

I left the company a year after this was put into full production, but the last I heard it kept the company viable with a supportable product for many years after until its owners retired. This kept software from the early 1990s running well into the 2010s, and there are likely still sites running it to this day.

I worked in a state gov't agency as a temp, twice, in the same department. Several of us had shared access to a PC that let us log-into a special terminal program and read records on some mainframe someplace. That PC had a 233-MHz cpu, I'll assume single-core. At that time, it ran Windows NT 4.0, and it had been patched to use a USB mouse. But we didn't rate an optical mouse, so someone would come in twice a day with a tote of cleaning supplies and clean the mouse ball.

After September 11, 2001, somebody came in from the federal government and ordered Windows XP to be the minimum OS for some security issue. The person who had to update that system said a 233 MHz machine was too-slow for XP, and she didn't have a replacement computer, she was already short on computers.

The next time I saw it, it was running XP.

I had a functional STA Compact [1] coagulation analyzer until 2022. It ran a customized DOS version on a ITX computer board that was integrated into the analyzer. UI was in text mode and used the keyboard only. It had no mouse. The video in the link shows the UI for a few seconds at the end. We kept it functional as a backup and even used it a few days when the replacement broke down. It was one of the best analyzers I ever used.

The newer version of that anaylzer, STA Compact Max [2] has mostly the same analyzer hardware, but newer ITX board inside. It runs Windows (XP, 7, 10...). Bugs galore.

I know labs that used a Beckman-Coulter HmX hematology analyzer [3] until 2015 or so. That machine is attached to an external MS-DOS computer via a very thick cable and an ISA board. The cable connector looked a bit like a 68-pin SCSI-3. The software used VGA graphics mode.

  [1] https://www.youtube.com/watch?v=Kti6Zdyp8dQ
  [2] https://www.youtube.com/watch?v=MJan25vkpEA
  [3] https://www.soriaudio.com/index.php?mid=m_eqp&document_srl=62138152

I know a shop that still runs an Apple ][: they have a Numerical Control machine. For those who don't know, NC is the predecessor to Computer Numerical Control, i.e. CNC machines.

They run on punch tape.

So this Apple ][ is connected to simulate the punch tape reader, and send the (I think) G-code commands to the machine. So it's now a CNC, managed by an Apple ][.

2014-2017 I was supporting a clipper setup for issuing work order and many other tasks for an old civil aviation repair plant. I’ve ended up virtualising and moving it to a hyperv cluster. Definitely the case of “if it works, don’t touch it”. Also set up a closed network for CNC machines to let engineers in the shop send jobs over the net instead of running around with floppies or manually entering gcode through the console. Fun times.

If "a few years ago" counts, a relative of mine abroad used an MS-DOS application attached to an Epson dot-matrix printer that supported a PITA foreign script to print invoices. It wasn't too painful, since the system supported batch jobs fed by a format that Excel could export.

Not DOS, but two similar era cases.

A FTSE 100 company I used to work for, still maintains a SCO UNIX machine that was first installed in 1993. It hasn't had any upgrades since, has specialist hardware in it, and still has an IP stack that is classful (ie. no subnet masks, 10.x.x.x is always a /8). It runs in a 100% airgapped network, and it isn't essential to keeping the core companies operations, but it is a ticking time bomb nobody seems to want to address that will cause a lot of distruption when it finally dies.

Also I was recently (very lightly) involved in a consultancy project to remove an OS/2 based point of sale system for a small local retailer with 6 stores.

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.

We have a client (a factory) I wrote a massive (for one person without AI) Clipper system for that runs the factory; this is decades ago but it just works and when they tried to replace it (not by us, but promises by others), it was worse and they did not switch. Cheating, but another client is a bank; they found its is really inefficient to not use DOS. Their machines use Windows but fullscreen DOS box you cannot close or minimize with the app in it.

Half of our system is running on 2002 versions software. To my desperation, my calls for updating has been persistently denied. There're no technical reasons to keep it as is, it's more about wetware issues.

We still use dBase files in some point as transient format, not using dBase as such though. Oh, and plenty of positional text files, but that's more a question of interop with partners.

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.

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.

An old story. I used to work for Fox Home Entertainment (CDs etc)this is 20+ years ago. And we had proper DOS running on old machines. We used it to do all our finances (including all of Japan, Asia sales). Most of the money we made on movies like Titanic were tracked on DOS. Until about 2003 if memory serves me where we moved to SAP. Why this was worrisome was how easily fraud occurred. In my tenure there $5-10M was stolen. At the time sent to companies in Brazil. I'm still surprised by larger firms where they keep these things alive to retain the data. CocaCola did it. A few large Insurance firms too. Crazy.

The Detusche Bahn still runs DOS and Window 3.11 in their ICE I trains! They searched for admins 2 years ago. https://www.tomshardware.com/software/windows/ms-dos-and-win...

AND more to the question - the contractor who remodeled my house in 2014 was still using some ancient DOS app, possibly running on a DOS machine or at least an emulator of one, to generate billing. Which was handed to me on paper....

(He was a good contractor, so clearly having the latest billing software is not the deciding factor in that.)

Not DOS but we recently had to virtualise a Windows XP box as it was running crucial software for a visitor attraction. The software was written by a member of staff who sadly passed away and the PC it was running on was approximately 20 years old.

We managed to virtualise it and then run it in a VM, and it needed a couple of USB-to-serial adapters passing through as well.

We're also finding some kiosks are running Shockwave Flash apps provided by companies that are no longer trading. We can decompile the files to extract the assets but at some point it's easier to just replace completely.

Me!

I have a client with some business software that runs on DOS. They have a dozen seats. A single Linux server gives serves a dozen VNC sessions with the software running in DOSEMU. Printing is done with the Linux print stack and three Ethernet print servers.

It has been working without a hitch since 2008. Oh, so has the server, which is a VirtualBox VM.

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.

The Gear cutting job shop I worked for had a CNC lathe running with a GE Computer from the late 1970s that stored data on punched Mylar tape, until it was bought out in 2019.

The bevel gear generator setup was some formula calculations running in version 1 of TK!solver, which would have been a $5000 upgrade to get the latest version, so they ran them under MS-DOS in DOSbox, and saved the grief.

Without that software, they would have to pay Gleason $500+ to do the calculations for each new gear setup.

There are strong and reasonable reasons to keep very old systems alive in offline production environments.

The last company I worked for still had customers they were dragging forward to get upgrades from coax connexted green screen terminals to modern network thin clients. It wasnt on DOS, but very old unix OS, tape drives for backups, parallel for printers, serial for scanners. No USB. Lovely troubleshooting when you were dealing with 30+ year old hardware setups. There was only one company that would even servicenthe green screens if they failed, and you couldn't buy them anymore.

My dad ran a commercial 2-way radio business. There were multiple radios with programming software that would not work on anything above a 386 and DOS. He had a couple computers from the late-80s running for nearly 25 years, though I think he had to replace one of them with another of similar vintage. Also, had a 486 that he used for customer notes in WordPerfect up to about 2015.

I suspect he could have found a way to use a newer computer, but if it ain’t broke…

Siemens Field PG. It is a rugged Notebook for PLC programmers. At least in the last version until last year, the "Field PG M6" was possible to buy the Notebook with a special serial port for old S5 PLCs ant the Step5 software came in a special DosBox version with it.

The Field PG has also another special port called "MPI/Profibus" for S7 PLCs, 2 Ethernet ports and a DVD drive.

https://support.industry.siemens.com/cs/document/109766662/d...

Does the idea make use of https://86box.net? Just heard of this recently on hn and it seems promising for anything that requires low level/cycle accurate emulation vs. your typical high level emulator.

One of our vendors is a contract electronic manufacturer (circuit board stuffer) that has a wave soldering machine running MS-DOS on a PC that's built into the control cabinet. It uses the parallel port to communicate with Opto22 industrial i/o modules, which then is wired to all the temp sensors, relays, etc. It just keeps working.

I work at a multi billion dollar facility for a Fortune 100 company and we still depend on DOS. Keeping the mandatory DOS machines going is an exercise. Especially integrating them into modern systems.

Edit: There is no required hardware, however maintaining a stable serial connection through a VM and timing issues due to faster hardware has been fun.

Just out of curiosity: is it possible to somehow attach an ISA Adapter via USB to a VM? ISA does depend a lot on DMA and timing, but the clock is only 8 mhz and gives a software layer on a modern cpu a lot of time to do stuff between ISA bus cycles.

Keeping old hardware running is very fragile. Most spare parts are decades old now too, and nobody knows if they still work properly.

Not DOS but another dad in my town works for one of the opera houses in NYC.

They have what are called "supertitles" [0] so that people can follow along with what the opera singers are actually saying. There is one on the back of each seat in the theater.

As near as I can figure, it's basically hundreds of LCD displays on some kind of bus network and connected to a computer via serial connection aka "D pin connector".

The software only runs on Windows XP and he has to keep finding old Windows XP machines on eBay in order to keep it working. I think he also has a couple hard drive images of the working OS + software.

I had suggested using a USB to D pin adapter and then use an LLM to sniff the protocol and then reverse engineer it.

His response:

"It HAS to work correctly. In 30 years we've never had an outage with the old system."

0 - https://en.wikipedia.org/wiki/Surtitles

It's not totally for business, but I run some antennae and radio telescopes that feed through a Gateway 386/33/16MB RAM. As well as a Getac, no idea what model, but it's from the early 2000s. They both feed through to a A/B switched Paradise CRT (so cute). dBase is on the list.

It's been a few years now, but I know a major manufacturer had some windows XP boxes around because they were the newest hardware/software they could get with native parallel port support to interface with their machines.

To give you an idea of the complexity of the manufacturing lines, shutting the machines down and starting them back up again was measured in days. Upgrading them would be obscenely expensive, let alone replacing them, just in the opportunity cost of not making anything alone.

I bet most AI is capable enough now to migrate you away to some emulator for a few dollars.

And I would even bet that in most cases you could run a solution on a sub $10 board from aliexpress.

I've an AMD K5 processor machine running at 100 mhz. for testing Transputer ISA cards when someone buys one, I also use the same machine to format and copy my Pascal compiler into a pair of 5 1/4" floppy disks. All using DOS.

Do scanners count?

I'm pretty sure they moved on from them, but a while ago I did seasonal work for a company that rented out scanners for year end inventory (tax related, IIRC). The scanners had to be "cooked" (flashed) on racks, boxed, and sent. The flashing usually worked, but on occasion, the scanner would fail the checksum or something and drop you into a DOS prompt.

One interesting thing of living in the AI era is that every single one of these old apps (that people still use and never paid big money to upgrade because it it ain't broke don't fix it) can now be rebuilt for $5 in ten minutes if you really know what to do (YMMV)

If you don't know, you'd have to pay an expert big money to do that and the migration abandoned just like before, so another decade will go buy until AI does that without permission just because it found a possibility for optimization and it is instructed to do so without human approval, because governments

i know still some accountant who use a DOS program to do his work because he hates the fact modern UI has load times. slows him down too much o.O (his program is all keybinds).

i do not have exp myself but i found it a delightful reasoning. i told him modern PC could also do the same on modern OS (ncurses or ratatui or so maybe) but that if he ask a programmer to make an upgrade he'd need to find the right kind of guy. He had someone do it few times but they came back with web interfaces.

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).

Wouldn't an example of the given scenario be writing code 50 or more years ago in mainframe COBOL, and then still expecting to run it to this day?

I don’t know the specifics of their systems but both of my local lumberyards here in SoCal still use DOS systems for their point of sale and inventory management, with slow dotmatrix printers and everything.

They simply have no reason to modernize. The one big benefit they’d have is an online inventory system but they make most of their money from negotiated bulk orders so there’s zero incentive.

I had to keep a disturbingly old machine with GPIB running until a few years back. They are still in operation in Australia (who we sold them to).

It was a test/repair bench for military aircraft avionics, with the only flying platform left using it being the legacy F/A-18 (A/B/C/D). Harris H-100 minicomputer hooked to an HP terminal and several full racks of GPIB test equipment with half of a rack of solenoids for switching between stimulus and response and which pin.

Not what you asked, but the question brought back memories.

I know of a DOS machine at a wool testing place that uses an ISA card based imager for measuring the micron and other things. They also have a supporting DOS machine with a dBase looking database on it. When I spoke to the owner he didn’t really understand the risks involved in running ancient hardware and in fact had a storage room with period PCs in it if the machines failed. He didn’t have much of a backup plan for the imaging hardware though.

My opinion is that if these guys are still running this gear, they already have a strategy in place (no matter how flawed) and would likely retire before throwing money at something they consider a non problem.

Good luck with the idea. It likely is a tiny niche market with customisation for every customer and given they are normally hardware constrained AI may not be much of a help.

All of them have no money as well.

I don't, but the abbey at the city I live has an ancient PC running a program from the 80s that controls the bell ringing.

I recall seeing it connected via a parallel port to a large board that then operates the switches/relays of the hammers.

We were talking about Visual FoxPro only a few days ago. [1] And one of those same companies in my comment [2] uses an old ordering system that is still in DOS and they boot up a VM to use it. They still have a printing machine ( not a normal printer ) for those order printing connected via a Parallel Port. I don't know the details of how that works though.

And by the end of all that, the order will be Faxed. Manually.

Did they tried to email it or automate it. Hell yes. Did it work? No.

[1] https://news.ycombinator.com/item?id=49808023

[2] https://news.ycombinator.com/item?id=49811716

We keep a FreeDOS machine at work for dialing in to configure and service paging terminals and using old two-way radio programming software.

Most of the stuff I've moved over to run in DOSbox but it's still in use occasionally for the software that's difficult to port over.

I did, for a while. Then, I used VMs. I haven't had a Windows VM for years.

If I were a serious gamer (I'm not), then I'd get a hardware rig, but otherwise, I've not needed it.

I had a doctor that kept an original NT machine, for many years, because his bespoke app worked on it.

I do, for two clipper programs. But no extra machine, just a VM. Until not long ago, it was running without VM on 32 bit Windows 10.