When did LF replace CR/LF in UNIX?
Never. Unix always took LF as newline--an interpretation
blessed by the ASCII standard. The convention was
inherited from Multics.
Interpolation of CRs was the business of drivers, not file
formats.
As far as I know, the only CR/LF terminal that original
Unix dealt with was the model 33 console. That was identified
by the fact that the login name was received in all caps.
IIRC the TTY 37 conformed to Multics practice on the advice
of Joe Ossanna.
Because of the model 33, login names were case-insesitive.
Come to think of it, I don't know whether they still are
in general, though they must be for email to be delivered by
login name.
Doug