[tex-k] Why write_ln is used before final_end in tex.web?

[Igor Liferenko]

Hi Karl,

I don't know any other people than you who can help
with the "last newline" problem.
I googled everywhere I could but failed to find any
information.

Please put description of how DEC PDF-10 _exactly_
behaves with regard to terminal output. TeX's excellent
documentation alone is not enough. We need to
know the idiosyncrasies of particular platform on which
TeX was written in order to adopt its behavior to other
platforms. While I was trying to
"reverse engineer" the behavior of PDP-10 I was totally
confused (no consistency here).
A video of an example TeX session on PDP-10 would
definitely be the most one could desire...

Specific questions:

1) if a program outputs nothing,
is an empty line printed between shell prompts?

2) is "line separator" printed before shell
prompt or after shell prompt?

3) is "line separator" printed in the beginning of
current line? (as opposed to "line terminator" which
is printed in the end of current line)
print_nl() procedure strongly suggests that this is so.
Again, to *separate* current line from previous line.

BTW, I found in tex.web why log file does not have the
"last newline" problem. This is because wlog_cr is
done explicitly before closing the log file, whereas
for terminal output wterm_cr is not issued.

    begin wlog_cr; a_close(log_file); selector:=selector-2;
      if selector=term_only then
        begin print_nl("Transcript written on ");
    @.Transcript written...@>
        slow_print(log_name); print_char(".");
        end;
      end;

Thank you,
Igor