Back in 1982 or so, when I was 15 or 16, my school was throwing out an ASR33, so I appropriated it. I had a Jupiter Ace microcomputer, whose claim to fame was

Back in 1982 or so, when I was 15 or 16, my school was throwing out an ASR33, so I appropriated it. I had a Jupiter Ace microcomputer, whose claim to fame was that it was programmed in Forth rather than Basic. Great little machine, commercial flop, so there was very little software and no hardware add-ons available. I decided to use mine to build a micromouse for a school project; a friend and I designed a parallel I/O board using TTL logic and veroboard to control the robot. Parallel port worked well, the robot sort of worked - had to build everything from scratch in the school metalwork shop. And then the teletype turned up, and I really wanted to use it as a printer. I remembering scouring the town libraries trying to find anything that explained this mystery RS232 protocol. I also had the usual teenager problem of lots of time and no money. In the end, I implemented RS232 using a 24V smoothed power supply scavenged from a scrapped ATM to give +/- 12V, a couple of power transistors desoldered from some other scrap board to switch the 12V rails, and bit-banged the protocol in Forth using one pin of the home-brew parallel port. Took a lot of trial and error to get the timing right, as I didn't have any test gear. Worked great in the end - as far as I know, I had the only Jupiter Ace with a printer, and it cost me precisely nothing. Happy days. The skills learned back then figuring things out for myself have served me well over the years in research.