There were
real semaphore systems used for communication. Then he layered a lot of early telegraph stuff on top of that, popped some of his own invention into the mix and finally used the rest to parody internet and mobile phones. It's magnificent really.
Speaking of sci fi - have you read Strata and Dark Side? They're pastiches of Asimov and Niven and so on, but he has some really neat ideas in there as well. I particularly like his notion of vacuum tube technology taken to its limits in Strata.
If ever I needed proof of the non-existence of a benign all powerful god then the fact that someone who loved writing that kind of intricate and clever sophisticated humour would be so cruelly struck down with Alzheimers would suffice.
"A life with footnotes", the biography of him by Rob Wilkins is excellent and very moving.