Anyone Remember multi person Gaming ( max 2 ) via Serial null modem cables
Ah Those were the Days
Before Networks Gained popularity
Ps Still have one in my Cable store
Many, but much later (mid-to-late-90's for me). My school had no network in the computer lab, so we used to bring null-modem cable to play Heretic w/ my friend.
Then, when we finally got our own PCs in college, and even though Ethernet/cable was already affordable in my area, we were still experimenting with stuff like dial-up private networks, ppp laser connections etc... The speed was horrible for anything other than IM or playing turn-based games, like Heroes of Might and Magic 2, But the geek-factor was through the roof.
I still have one cable in my workshop for diagnosing managed switches and other networking equipment, which my neighbor brings-in for repair. I also hate USB-RS232 converters and cables, cause they always break in the most unexpected situations. Usually it's either my stationary SFF PC w/ Serial port, or my old D620.
P.S. Also forgot one important example: digital coin/token/bill acceptors and most embedded credit card readers also use serial communication (except those shitty chinese coin acceptors w/ pulse signaling). If you ever had a chance to look into one of those payment terminals or ATMs, you'd probably notice something like a typical SoC board, but with 3-4 or more serial headers for all peripherals. There is a local company in my area which makes those from surprisingly mundane parts, like old cheap Atom N570 boards w/ LVDS interface, some serial bill acceptors and card readers, logitech webcam and the cheapest available laptop LCD screens w/ chinese 15" digitizer panels. All communication is done through 2G, cause there is not much traffic from each terminal, and some local cell service providers now offer cheap IoT plans at less than $0.40/mo per device.