You should take a look at serial-to-ethernet converters like the USR-TCP232-T2. I use one with my VIC-20 to telnet into BBSs. Uses a modified AT command set,

You should take a look at serial-to-ethernet converters like the USR-TCP232-T2. I use one with my VIC-20 to telnet into BBSs. Uses a modified AT command set, so you can actually control it a bit like a modem. Picked it up for $10 off eBay a few years back.