sounds like the definition has changed since you were in college:
'A programmable logic controller (PLC) or programmable controller is an industrial digital computer' [0]
PLCs that are computers with digital processors have been around since about 1984. It is exceedingly rare for any digital equipment to still be in service that is more than 30 years old. The equipment may still be working fine but nobody is around who knows how it works, how to program it, or what to do if it stops working. A real con for digital and pro for mechanical systems!
Of course all of the analog systems that preceded the digital ones have been ripped out too. Nobody could be bothered to learn how they worked, parts became scarce, and digital is so much cheaper and faster to develop and own!
Maybe I'm mis-remembering plD where D was device, but at the same time a single letter of differentiation, and one that is pronounced similarly, is asking for this kind of error in communication/memory.
'A programmable logic controller (PLC) or programmable controller is an industrial digital computer' [0]
PLCs that are computers with digital processors have been around since about 1984. It is exceedingly rare for any digital equipment to still be in service that is more than 30 years old. The equipment may still be working fine but nobody is around who knows how it works, how to program it, or what to do if it stops working. A real con for digital and pro for mechanical systems!
Of course all of the analog systems that preceded the digital ones have been ripped out too. Nobody could be bothered to learn how they worked, parts became scarce, and digital is so much cheaper and faster to develop and own!
[0]: https://en.wikipedia.org/wiki/Programmable_logic_controller