Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!dogie.macc.wisc.edu!uwvax!per2!dag
From: dag@per2.UUCP (Daniel A. Glasser)
Newsgroups: comp.sources.bugs
Subject: curses/termcap vs. autowrap on DEC terminals
Keywords: autowrap vt220 vt240 vt340 vt330 curses termcap
Message-ID: <853@per2.UUCP>
Date: 2 May 89 17:52:56 GMT
Organization: Persoft Inc., Madison, WI
Lines: 30

[[ I realize that this has probably been covered before.  I am posting ]]
[[ this because some people are still running into this problem.       ]]

There is a problem with some implementations of the curses library
in its interpretation of the autowrap on DEC terminals (VT100 and
later).

The specific problem is that the curses screen update routines
believe that if a character is written into column 80 that the
cursor is left in column 1 of the next line.  The actual behavior
is that the cursor remains displayed in column 80 and does not
move until the next character is received.  If the next character
is a linefeed, the cursor moves down to column 80 of the next line
and the next character received (assuming it is printable) will be
displayed in column 80 of that line.  This is also true of the
relative up/down positioning sequences.

Many "VT100" clones/emulators do not mimmick the DEC terminal behavior
properly.  Some do.  The best bet when you find programs screwing up
the screen display through curses is to make sure the tab settings
on the terminal are the default 8 column tabs (9 17 25 ...), that
the TERMCAP entry for the terminal has auto margins false and that the
terminal itself has autowrap turned off (this should actually not
be required).

-- 
 _____________________________________________________________________________
    Daniel A. Glasser                           One of those things that goes
    uwvax!per2!dag                              "BUMP!!!(ouch)" in the night. 
 ---Persoft, Inc.---------465 Science Drive-------Madison, WI 53711-----------