Seem likely. The monitor shown at 1:09, 1:58, and 7:25[1] on the "TSMC Fab Tour" video on this page[2] looks suspiciously like Windows 95, but could be Windows Embedded I guess.
The main defense is a computer at the entrance where technicians are supposed to scan their USB drives. It's a devils choice really...do you put the tools on an externally accessible network? If not how do engineers get data off of tools? how does the factory talk to itself and schedule things?
I don't envy FAB IT. Utterly thankless.
Same thing with your OS/2 system. As long as it's working, there's really no need to change it. The fun begins when it no longer works and needs to be replaced. How much of the factory will then need to be replaced/updated just because the controlling computer can no longer operate the older equipment? That's the type of scenarios that give managers nightmares.