Maxim pioneered the charge-pump-on-a-chip concept with their groundbreaking MAX232, the first time you could get a single chip RS232 interface going without having three power supplies. Fantastic little device.
Came here to say exactly that. The MAX232 is a staple of RS232 connections to microcontrollers. +5v/-5v (maybe it goes higher?) with a couple of electrolytic caps and that's it
