1. Things like CNC machines and proprietary interfaces to TOL equipment, like bus fare systems, message boards, etc.
2. Don't connect them to the Internet (most can't, anyway, but some systems use a run-of-the-mill PC, so...)
3. Don't install anything on them that wasn't supposed to be installed, even wallpaper as this could fuck up the resolution of a small 240 x 180 screen

We run it in a lab, one of the microscopes we have is no longer maintained, and there is no driver for a modern OS.

It's completely offline though, we copy the images onto a flash drive and then move them over to the production system manually, so there's no need to update or fix anything just yet. It's the same old computer. I've got a full set of replacement hardware though, just in case.

Look man, I just really like Space Cadet Pinball.

Probably plenty of critical infrastructure and medical systems.

I've got a number of embedded systems that use a Java client which can't work on a modern system. I run XP in a VM with an old version of Firefox and Java on it to get into those. Works great!

Up until a few years ago, I had a flight simulator running on Windows 95. It too, ran great and was certified for students to log flight time towards their certifications.

Quite a few people here sound like ideal candidates to try ReactOS. It is an open source implementation of the NT architecture and should generally slot in for most software including drivers. It works quite well and plenty of people have managed to get old hardware working on ReactOS that was not otherwise ssfe to connect to a network. It works just like Windows NT and looks very similar but also supports more modern security standards and software.

We have a few clients that use them to control the CNC machines they have.

The machines are isolated from all other devices on the network and can't see the internet.

The machinists run their gcode files from USB sticks that are walked from their machine to the CNC

Still using W95 to program some FPGA, coupled to a 8086 with a program written in assembler and Ada. It's for aeronautics application. It was proven in the 90s and still used/sold nowadays

I know a doctor who's been running a research project since the 90s using a database application with a proprietary format. Said doctor had the option of upgrading to a version which was a front-end to Excel in the 00's... but didn't... and then the company sold their product to Microsoft and closed down, taking their format conversion app with them.

I also know a test lab using a blood gas analyser running off a built-in Windows NT PC. Those things cost an arm and a leg, so they'll keep running it until it dies and replace it with something more modern.

I've got a couple of old laptops running it. Play a few old games on them occasionally. My only workaround is to never connect them to the internet!

You know i woke up today with a furious urge to buy an old Windows XP computer and play old games on it. Of course i wouldn't ever connect it to the internet.

I suspect i might be setting myself up for major headaches

One of my machines at work is still running on XP. Runs a CAD/CAM program and talks to the PLC of a fair sized 2D CNC mill. I prefer it to the machine running on Millennium.

I have an old CNC machine driven by an XP laptop. XP runs great, I just don't mess with it and of course keep it off the internet.

Airgapped XP Pro on an old IBM laptop (somehow in near mint condition) in order to manage files on a Creative Zen. Linux can see, but not manage. Win10+ can't even see.

Edit: I checked the model, if anyone is interested. It's an IBM ThinkPad R51.

Man, i feel strange still running 10.

At work we have one old PC on Windows XP for the ancient PBX phone system we are currently using. It runs fine, it is only there to run specific programs so it's not like we install/run anything else on it. And it's not exposed to the internet.

The hardware will die eventually but until then my boss is too cheap to spend the money to replace the entire phone system.

i don’t necessarily use it, but i mess around with an xp vm a lot. for web browsing there’s mypal (which is old but still mostly functional firefox) and supermium which is somehow chrome 122 on xp. there’s also one core api for running more modern apps, but i haven’t ever tried it.

overall, xp is surprising usable for most people considering “usable” means “there is a modern web browser” but i still wouldn’t recommend it since xp is 23 years old.

There are some CD-ROM games I run on XP in a vm.

Yes, I have a 2008-era build running it. It's glorious. Not really many fixes other than installing all the updates up to 2019, and making sure to manually run SSD tools to trim my drive.

I have an old film scanner (was pricy back in its day) that doesn't have drivers for 64 bit Windows, and anything newer than Vista. So I have an old XP box that can talk to it.

That's all I use that computer for, so it's otherwise fine with its circa 2009 configuration. Haven't had to do any fixes or workarounds.

My neighbour is. I hear the boot sound about once a week. No idea what he's using it for, but I hope it's not connected to his network.

Every single relevant government office I've been to. How I wish not every single piece of machinery was from 20 years ago.

I have a bunch of retro machines, and one of them is running XP. Not long ago I enjoyed No one lives forever on it. Nothing beats the correct hardware.

Regarding fixes, Service Pack 2 is enough. And since Steam is not supporting retro machines anymore there is no reason to connect it to the internet anymore, thankfully gog let's me download the installers, all the more reason to use gog exclusively. At least for my special gaming tastes.