Old hardware or emulation of old operating systems on new hardware.
Quite common on old industrial machinery and other capital equipment like lab equipment. San Francisco BART for example has to scrounge eBay for old motherboards that still allow DMA to parallel ports via southbridge because it’s too expensive to validate a new design for controllers.
I have a G5 with a bunch of old boxed software that runs as well as it did the day I bought it. And an Xbox 360 with the same. Not everything has to keep up with the times.
I remember visiting a doctor, about ten years ago (so well into the 21st Century). His laptop was an old one, running NT.
The software they would buy, cost tens of thousands of dollars, and they couldn’t afford to keep upgrading (or the original vendor went belly-up).