Those were fun times, for sure. I got on the Internet fairly early (1991-ish), mostly through not-quite-legit means. Later on I got some jobs at early ISPs and helped a couple others get started. In those days, if you could configure a T1 and set up a couple static routes, you were considered a god.
I helped start a pretty successful ISP in Chicago (EnterAct) in --- I think? --- 1995, and it was bizarrely easy. By then, CLECs would deliver you a PRI (I think?) that would terminate calls from every suburb in Chicago, so you just needed a rack, an ethernet connection to an upstream, the PRI, and a couple of terminal servers to get started. We had a DS1, connecting our cage at MFS to our offices, but our actual upstream was just 10bT.
For a long time, I routed the whole thing with proxy ARP. :)
PRIs arrived a bit later around here, and definitely changed the game. I think it was late 1996 when they started getting popular. Before that, it was stacks and stacks of modems! I remember going into one of the main POPs and there were metal shelves, over 150 modems (Microcoms, I think?), power strips 3 layers deep, individual serial cables to terminal servers, and a river of RJ11 phone cables coming out of the wall. All this was in an unconditioned basement in a small office park. All those blinking lights sure looked cool though.
Our upstream was a couple T1's to two different providers. At some point, there was a billing dispute and one of the T1's got shut off. Everything was lagged for weeks. I forget the brand of terminal servers, but they booted off floppies, and stored their password file there, too (this was before RADIUS was deployed.) Crazy times.
