Once you have telnet you just get an SDF account and do anything you want with a Unix shell. And, if you fire up Emacs, you are god. IRC, EMail, Jabber, Mastodon, gopher, gemini, a calculator, a Lisp environment, play ZMachine games with Malyon (and spawn full v5 and v8 games unlike the Speccy which could just handle v3 ones)...