> I just read a TTY model 28 manual about the stunt box and I didn't see anything specific about FS/GS/RS there.
The Model 28 was a 5-bit Baudot (ITA2 code) machine with a stunt box. The Model 35, an ASCII machine, had a similar system, with different coding.[1]
The term "Selective calling" replaced "stunt box".
ASCII-67 is modern ASCII, but there was previously ASCII-63.[2] That keyboard has special keys for selective calling. WRU, RU, EOT, EOA, TAPE, ~TAPE, etc. Codes didn't become standardized industry-wide until ASCII-67. Before that, there were lots of variations.
Here's a popular view of the process in the Baudot era.[3] That big switching center is essentially Sendmail built from of relays and paper tape equipment. It was called "Plan 55-A".[4]
The Model 28 was a 5-bit Baudot (ITA2 code) machine with a stunt box. The Model 35, an ASCII machine, had a similar system, with different coding.[1] The term "Selective calling" replaced "stunt box".
ASCII-67 is modern ASCII, but there was previously ASCII-63.[2] That keyboard has special keys for selective calling. WRU, RU, EOT, EOA, TAPE, ~TAPE, etc. Codes didn't become standardized industry-wide until ASCII-67. Before that, there were lots of variations.
Here's a popular view of the process in the Baudot era.[3] That big switching center is essentially Sendmail built from of relays and paper tape equipment. It was called "Plan 55-A".[4]
[1] https://www.smecc.org/teleprinters/35selcall001.pdf
[2] https://lostbits.net/blog/the-teletype-model-35-character-se...
[3] https://youtu.be/PKJyGuhCQdQ?t=369
[4] https://en.wikipedia.org/wiki/Plan_55-A