Same with industrial automation. There’s some robotic arms, assembly lines, etc in use today that still use PCs with ISA slots - the predecessor to PCI, which was the predecessor to PCIe. Old 16-bit bus that could only transfer a max of around 5Mbps. That’s why you’ll occasionally see newish “industrial” motherboards that have ISA slots and parallel ports.

A project I worked on at university (way back in 2010) was for one of the largest providers of air traffic control systems. Our project was interesting - usage of eye tracking and screen recording via VNC for training of air traffic controllers - but it was even more interesting to learn about some of their processes.

Whenever they built an ATC system for a client, they’d build one or two spares at the same time, with exactly identical hardware. They did this for two reasons:

1. If the hardware breaks down, they can supply a new system that exactly matches the hardware that was verified.
2. If a client has an issue with their system, they can try and replicate the issue on a clone of that client’s system.

We got to see a storage room with a large number of these systems. Lots of different PCs anywhere from a month to maybe 15 years old. :)