I know of a small company run by a retired man, that designed and installed several industrial control systems. All of these are air-gapped and run by very old computers on DOS 3, I think they might be 16-bit. It's run by him and him alone. He travels out to fix them in different cities once in awhile. I asked in passing if he tried moving to VMs, he has but didn't describe it, he said it didn't work out.
I wrote a pizza ordering application back in 96 using turbo pascal 7. The software got pirated and is still used by some places where they take phone orders.<p>Most software at the time used mouse clicks, mine had an interface where you could use keyboard shortcut to add ingredients. It was like 20 times faster to take an order.