[mark-r]

The standard line ending of the '70s was CR/LF, because the printers commonly used as interactive terminals required them both. I wonder how that worked on the first Unix systems?

[cesarb]

> I wonder how that worked on the first Unix systems?

Probably the same way it still works on today's Unix systems: it converts NL to CR+NL on output. See the manpage for the stty command:

  Output settings:
    [-]onlcr
      translate newline to carriage return-newline