🚀 go-pugleaf

   Flow-Problems with Terminals
   ----------------------------


Hallo everybody,

Does anybody use EMACS with Terminals like DEC VT220 or
TransTec-Terminals emulating VT100, VT200 or VT220 ?

Configuration :

DEC 5000/120, Ultrix V4.2A (Rev. 47), Terminals DEC VT220 
and TransTec GDT6225 with 9600 baud

EMACS 18.58.2.


Problem :

The best way to run EMACS from Terminals is to configure
the Terminals to hardware-handshake. Then one can use
the CTRL+S key to I-SEARCH. This does not work on this DECstation
in principle. It seems to be a hardware or a Ultrix problem.

So we tried the software handshake XON,XOFF. The Terminal works
correctly with normal displaytask like "more .." and the VI editor.

To run EMACS we said in the "~/.emacs" file :

    (global-unset-key "\C-S")
    (global-unset-key "\C-Q")
    (setq search-exit-option nil)
     
Now EMACS should understand XON and XOFF as XON and XOFF.
(to use I-SEARCH we must bring it to another key)

If you start EMACS with a file with only an few lines everything
is ok !
If the file have eg. 100 Lines EMACS comes up with a correct
first display, but if the cursor is moved down the display is not
scrolled correctly.
The Terminal has about 250 bytes of buffer. Only the first half screen
is restaurated correctly and then a XOFF-XON sequence might happen and
the hole second part of the transmission, about 200 bytes, is lost.

Why does the standard tasks run on this Terminal and only EMACS do have
such a typical handshake-problem ?

Of cource the files ../emacs/lisp/term/vt200.el and so on are readable
for the emacs-user and "term" environment is set to vt200.

It really must be a handshake-mistake as Terminals with the same configuration
but a bigger buffer like PCs or Ataris emulation VT200 work on the same 
tty-line without trouble. 


Stefan Ried

Institut fuer theoretische und angewandte Physik, Uni Stuttgart, Deutschland
email: stef@itap.physik.uni-stuttgart.de