rcw@qetzal.UUCP (Robert C. White) (12/20/87)
[Dick Dunn relates a problem with his modem using System V/AT in
the following article. Please send speculation/answers using the
"R" key. Summaries will be posted. --Robert White]
I've had a problem with a modem getting stuck in a strange state when using
uucp. I don't know whether it's a problem with the modem, the software, or
the combination.
Behavior: Uucp will run fine for a while--anywhere from a couple of
sessions to a dozen or so. Then it starts failing and won't work again
until I cu directly to the modem and sweet-talk it into listening again.
The problem, in the wedged state, is that the modem doesn't respond. The
uucp log messages are like:
someone!uucp (12/19-5:15:58) (C,1456,0) DIALER (No answer)
someone!uucp (12/19-5:15:58) (C,1456,0) FAILED (call to someone )
Here's the fun part: When I connect directly to the modem with cu, the
first character I type is echoed wrong! All characters after that look OK.
It's always one character echoed wrong (for particular input; read on),
and it's systematic: If I type any of the characters A thru G, the
character echoed is q thru w, correspondingly. For example, if I try to
type "ATE1", what gets echoed is "qTE1" and the modem doesn't recognize it.
However, some characters WILL get echoed right in this condition--if I
type an H, it echoes correctly! I haven't had the patience to try all
possible characters as the first one in the wedged condition, but it seems
that A-G or a-g give the q-w echo (echo is lower case for either upper or
lower case typed), while H-Z or h-z echo correctly. There seems to be some
relationship of bit patterns of character to whether it's echoed wrong and
to what the wrong character will be.
It would be kind of an entertaining problem if I didn't want to depend on
uucp.
The hard part of the problem is figuring out where to start--the fact that
the condition goes away after one character makes it nasty. Whatever it is
that uucp (or the dial code) does, it doesn't manage to tickle the modem hard
enough to unstick it.
Vital characteristics:
OS - Microport Sys V/AT 286, Version 2.2.0
Modem - Leading Edge "Model L" 2400 (used at 1200)
Machine - NEC APC IV
Anyone have any idea what causes this? Anyone else seen it or have any
suggestions? (Talking to the modem manufacturer is of no use at all--
they're happy enough to help as long as you're running DOS.)
---
Dick Dunn {hao;nbires}!ico!raven!rcd (303)494-0965
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