[rescue] VT420 ConnectivityQuestions

[Jim Carpenter]

On Mon, May 2, 2022 at 8:41 PM Lionel Peterson <lionel4287 at gmail.com> wrote:
>
> I researched this a while ago, but now I can't find it: can I connect to a VT420 terminal through the DB25 connector on the back, or do I have to use either of the MMJ ports?
>
> My initial tests tell me the DB25 is simply for a local printer, the terminal sessions want to be on one of the MMJ ports, correct?

You have 2 MMJ and 1 DB25? That's the international version. You can
use the DB25 or the MMJ next to it. The other MMJ is for the printer
but I think can also be a comm port; the VT420 can do multisession.
You should select the port you're using in the terminal's SetUp.

See https://vt100.net/dec/vt420ps2.pdf , PDF page 23.

> Can someone help me configure a 'no soldering' solution to connect my VT420 to the on-board UART on the RPi 4 GPIO pins? I assume www.pacificcable.com is the preferred vendor, and what I need is a cable to go from MMJ on the terminal to a DB9 Female connector, probably null modem, since I want to hook the terminal to the TX/RX pins on the RPi 4 thru a level converter that takes TTL-level signals to 'proper' RS-232 level.

I'd forget the MMJ and the GPIO pins. A cheap USB->DB25 adapter would
do the job easier and possibly better. (Does the Pi UART support
RTS/CTS??) Just pay attention to gender and whether or not you'll need
a null-modem adapter too.

Jim