3 ms·
About the teletype -- I didn't think they used RS-232, but a current loop (like a telephone) with some early pre-ascii (5-bit?) encoding?
by ams6110 9y ago
About the teletype -- I didn't think they used RS-232, but a current loop (like a telephone) with some early pre-ascii (5-bit?) encoding?
- mhandley 9y agoIt's been a long time, but I'm fairly sure it was 110 baud RS232, 7 bit ASCII, all upper case. I think it was an ASR 33, or at least I recall it looking like this: https://en.wikipedia.org/wiki/Teletype_Model_33 https://en.wikipedia.org/wiki/Teletype_Model_33 Unfortunately I don't have it any more - my parents threw it out a few years after I left home. Wikipedia certainly implies the ASR 33 used current loop. If I recall correctly, mine had a DB25 connector, which likely indicates RS232, and is probably how I figured out it was RS232 in the first place, as information was hard to come by back then. I do know I used a 24V power supply from a cash machine, using a potential divider to create a +/- 12V signal, which is consistent with the model I had having an RS232 interface. Getting the timing right in software was a lot of trial and error. Edit: this page indicates that RS232 was available as an option on the ASR-33 teletype: http://bytecollector.com/asr_33.htm http://bytecollector.com/asr_33.htm
- raphlinus 9y agoI had one of those too, an ASR 33 with RS-232. I connected it to an Intel SDK-85, which had optional RS-232 stuff on it. Fun times! If I recall, the teletype was sourced from the Green Bank Observatory, which had some really impressive old equipment - racks of hardware with nixie tube displays, all that kind of stuff.