Just to be "that guy" for a minute...
Windows 98? The DLR (Docklands Light Railway) still uses computers from the 80s for their self driving and signalling systems. They have a room full of them and when the last one dies, that's it.
London Underground were at one point the worlds largest manufacturer of vacuum tubes for their signal systems (can't buy them, I guess we have to build them)
Train systems are one of the ultimate examples of people not thinking long term, complex systems and infrastructure that cannot be closed even for a few days. So you often get these weird special cases.