Half-duplex VT420?

From: Iggy Drougge <optimus_at_canit.se>
Date: Tue Oct 9 18:23:08 2001

Tony Duell skrev:

>> from the terminal. So I tested it with my DECstation. No response there
>> either. So I hooked it up to my Amiga. Typing at the keyboard, there was
>> output in NComm, but doing the opposite didn't work at all.

>I reat this as you can send from the terminal to the amiga, but not the

I'm sorry, I sent that message off before I'd finished it. But your
interpretation is correct.
I've also tested the cables.
With the nullmodem I'm using right now, I get a whole line of reverse question
marks when the HP does its double-beep to signal that it's entered the self-
test sequence. It works fine when the Amiga's acting as a terminal, both ways.
The VT seems to sense that there is communication going on, though, since
whenever I press return, and the HP generates a new prompt, additional
question marks are printed.

>> So we have only one-way communication. What could be the problem?

>Well, most setup faults (like enabling handshake lines) stop the terminal
>from sending, not receiving, so we can discount those.

>Most likely it's a hardware problem in the terminal. My first suspect
>would be the RS232 receiver chip, which may have been damaged due to a
>spike on the comms line. Open up the terminal and trace the receiver input
>from the RS232 connector (pin 3 if it's a DB25 connector) to the chip. It
>may be a 1489, it may be something more exotic (I don't have the prints).
>Change it and see how you get on.

Will do, as soon as it discharges.
BTW, the VT420 service manual has recently been uploaded to
http://www.vt100.net/, though it's a bunch of multi-page TIFFs, so I'm unsure
what programs will support those.

En ligne avec Thor 2.6a.
Schont die Sockel, wenn ihr die Denkm?ler st?rzt. Sie k?nnten noch gebraucht
--- Stanislaw Jerzy Lec
Received on Tue Oct 09 2001 - 18:23:08 BST

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