You could add multi-protocol networks to the list. Almost all sysadmins today only have to worry about TCP/IP versus back in the 90s your network usually suppor

You could add multi-protocol networks to the list. Almost all sysadmins today only have to worry about TCP/IP versus back in the 90s your network usually supported at least two and possibly all of the following protocols: TCP/IP, IPX, VIP, DECnet, LAT, SNA, and NetBEUI. There are plenty I'm leaving off the list. Token ring was mentioned but other LAN technologies around in the 90's that are dead or mostly dead include 100VG-AnyLAN, ATM LANE (emulates an ethernet network over ATM), FDDI, TCNS (basically 100Mbs ARCNET), proprietary pre-802.11 wireless technologies, proprietary layer 3 ethernet switching technologies (looking at you Cabletron and 3COM). I worked with all of these at some point during the 90s. Some were a pleasure to use and some were not, but ATM LANE deserves a special place in hell. I started out the 90s connecting systems to 9600bps x.25 networks and ended them deploying millions of dollars of Juniper M40 routers and Fore ASX-4000s ATM switches per day. Both of those vendors would have probably appreciated my employer actually paying for them. It was a crazy decade.