[net.emacs] VT100"s and the AM capability

mark (03/23/83)

Termcap in fact DOES provide a "weird automargining" capability, it's xn
(eat newline glitch) and was put there specifically for concept 100's and
vt100's.  (Version 3.6 and earlier of vi did not handle it properly on a
vt100 - the fix is trivial and was in 3.7.  You just arrange to output an
extra \r\n in the place where an extra \n was output.  Search for XN (there
are two of them in vi) and fix both, and do it carefully - remember that
putchar takes only single characters and you'll need a set of curly braces.

	Mark Horton

flon%usc-cse@USC-ECL (03/27/83)

The problem that triggered my question was exhibited by libcurses, not
vi or emacs.  In a screen update, with AM in the termcap entry, curses
decided to clear the rest of the current line and get to a position on
the next line by spacing to column 79, then tabbing (it thought with
wrap) to the place on the next line.  But all the tabs got absorbed by
the vt100 without wrapping.  curses behaves correctly (differently) with
AM missing.

Is it perhaps the case that the vt100 is even weirder than one suspects
at first, in that it needs a SPACE to wrap, but won't accept a tab?

	Larry