Problems with less,emacs,etc. on VT420 on ttyS0...

[Daniel Freedman <freedman@ccmr.cornell.edu>]

Hi,

I have an actual VT420 terminal connected to ttyS0 of my Linux box,
running Debian woody/testing, and am having trouble using certain
programs (e.g. less, jed, emacs, etc.) on the terminal, though others
(e.g. lynx, vim, more, etc.) run fine.  I've tried configuring the
VT420 through its setup both using Xon/Xoff (software) flow control
and (probably) the preferred hardware (VT420 calls it modem) flow
control (which uses DTR/DSR lines).

I'm runing agetty (Debian's getty) to set up the terminal login
prompt:

getty ttyS0 9600 vt420

(I also use the -h flag when I enable the DTR modem control in the
VT420's setup.)

The primary problem is that less, for example, automatically stops
after displaying the first screen, jed stops immediately upon
invocation, and emacs doesn't like to run with Xon/Xoff at all (which
I believe is a known issue), but also displays lots of junk (probably
buffer overruns) even when I use hardware flow control, which I
believe should stop this.

I thought it might be something with ncurses not getting along with my
flow control, but my TERM environmental variable is properly set at
'vt420', and lynx works fine (and uses, I believe, ncurses).

I'm wondering if, at least for the hardware modem flow control stuff,
it might be that the linux kernel's serial driver doesn't support
DTR/DSR flow control (I'm running 2.4.16 on this box), but I've not
been able to get a good handle on whether this is true.  Grepping
through the serial.c source showed references to DTR/DSR, but none
that enabled me to nail down its level of support.

I believe that my cable is properly wired (followed vt100.net
instructions).  I have an MMJ null-modem cable, and connect TXD+ to
pin 2, RXD+ to pin 3, DTR to pin 8, DSR to pin 7, and TXD- to pin 5 of
my DB9 serial connector on my linux box.

Anyway, bottom line, has anyone had success running these types of
applications on a vt420 (or other vt) in a similar setup?

Thanks so very much for any and all suggestions.

Take care,
Daniel

-- 
Daniel A. Freedman
Laboratory for Atomic and Solid State Physics
Department of Physics
Cornell University