Am I the only one laughing at the thought something from the early 90s is now considered antique?
Ha, darn kids probably can't fathom the idea that there were real computers in use by companies and organizations before those flashy single chip microprocessor based PCs were all the rage.
Thankfully there was at least mention of Zilog's Z80, terminal servers, RS-422/485, and green screens.
Bunch of whiny kids. Next they'll complain their first automobile or hand-me-down cathode ray tube colour television doesn't have WiFi and a web browser. Get old my lawn.
Heck, I develop, maintain, and extend software that's over 20 years old. I've worked on software written before I was born. Software approaching 50 years old is more like what I would consider ancient. Like much of the insurance and banking industry in Europe and North America.
So. my serious bit: Learn about industrial computer market, products, and vendors. Use industrial USB to RS-232C converter in most cases (where timing or bit banging isn't used), not the $5 USB-to-serial adapter from the big box electronics store. Take a class from your local community college if PLC or ladder logic is relevant to your environment.