Most of them in my experience. Many industrial machines have lifespans well beyond 15years. Big companies buy the state of the art and when they decide to replace the old machines they resell them to smaller companies who can't afford to buy the newest model.
I know many people on HN work in web technologies where last year's technology is already obsolete but I've worked in small hardware companies that still used industrial equipment controlled using a serial keyboard with a DIN connector and a monochrome CRT. I've seen people order parts for 20+yo industrial soldering ovens.
You can't really tell somebody with a highly expensive, perfectly functioning industrial machine that they have to buy a new one because you can't find the driver for the motherboard of the controller.
Back in my IT days we used a laptop that had a windows NT 4.0 sticker on it (running windows 2k) to run the ID printer that printed company IDs. These kinds of setups aren't that uncommon. At small scale it's easier and cheaper to keep old stuff running than to migrate.
I work in Manufacturing IT, I can confirm that there is considerable legacy equipment. Thing is, these machines typically cost more than a house, some as much as $2.5M+ dollars. Would you demo your house and rebuild in 20 years because of a leaky roof? These machines are mortgaged the same way, the bank secures the asset. They will work for 20+ years if you maintain them, and continue to produce.
I know many people on HN work in web technologies where last year's technology is already obsolete but I've worked in small hardware companies that still used industrial equipment controlled using a serial keyboard with a DIN connector and a monochrome CRT. I've seen people order parts for 20+yo industrial soldering ovens.
You can't really tell somebody with a highly expensive, perfectly functioning industrial machine that they have to buy a new one because you can't find the driver for the motherboard of the controller.