386, 486, good grief! Why on Earth are you keeping that junk? Let me guess...you keep using the same toothbrush until the last scraggly tuft falls out.
Because you find various perfectly servicable industrial machines that have an integrated controller with early 3/486 cpus in them. Nothing wrong with the machine, but you can't update the software any more, and you can't change the controlling machine because it uses some weird proprietary hardware so what to do? If you can put Linux on it chances are you can hack together some working control code, which is a damn sight easier than trying to work out how to get a modern PC to talk to whatever the hell it is.
Biting the hand that feeds IT
