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I’ve always wondered: does the carriage return key on an actual teletype machine do CR+LF in one button press? I know these were separate levers on old typewrit

by pram 4y ago

I’ve always wondered: does the carriage return key on an actual teletype machine do CR+LF in one button press? I know these were separate levers on old typewriters, but it seems like the “return” key has always done both.

blueflow 4y ago
It doesn't. It only sends LF. The tty line discipline patches that up. Edit: LF, not CR, but its not universally like that.
- pprotas 4y ago
  The Carriage Return key doesn’t send CR, but sends LF instead? I am so confused
  - blueflow 4y ago
    I was correct in the first try, it does send CR, and the tty subsystem replaces it with a LF (icrnl setting in stty).
defrost 4y ago
The Teletype Model 33 ASR keyboard has two seperate keys, one for carriage return, one for line feed [1], [2]. These correspond to the it primarily being a printer with control codes, with keyboards, tape punches and tape readers being additional (in various incarnations of the larger Teletype device family). The codings are distinct to enable overstrike and faster "next line w/out return" mechanical performance. [1] https://en.wikipedia.org/wiki/Teletype_Model_33 https://en.wikipedia.org/wiki/Teletype_Model_33 [2] https://en.wikipedia.org/wiki/File:Mappa_Teletype_ASR-33.jpg https://en.wikipedia.org/wiki/File:Mappa_Teletype_ASR-33.jpg