Date   : Sun, 28 Jul 1985 22:43:00-EDT
From   : ABN.ISCAMS@USC-ISID.ARPA
Subject: USR Autolink Modem Problems

Netlandians,

I've been working through a US Robotics Autolink 212A 300/1200 baud modem
from my micro thru a local TAC to my host on the ARPANet.  The local TAC uses
Racal Vadic 1200 baud modems, and the TAC wizards tell me it's a Bell 212
protocol modem, not the 212A.

Never thought that made a real difference, but I got problems!

During fast typing in terminal mode (right here in the editor of my mailer,
Hermes, for instance), I will suddenly get a short burst of garbage and a
lockup!  My modem lights indicate I continue to send out, but NO incoming
data.  Thought for a while the TAC modem was hanging up, but not true:
it continues to receive my commands (transmitted in the blind as it were)
and respond to them.

After much experimentation, it appears that MY USR modem is somehow losing its
incoming data!  Turning it off somewhere on the board or something.  If I very
quickly pulse the on/off switch (and am lucky enough not to have the phone
or far modem hang up on me!), I regain the incoming data channel again!

I also experience this lockup when running Kermit on my host - usually at the
exact same packet - and when doing a straight upload (using XON/XOFF flow
control at the TAC to insure I don't overflow its buffers) into a text editor.
(Sorry, during Kermit, that's during Sends to the distant Kermit only.)  So
the problem appears to be related to my modem sending somehow!

I've turned off echo at the TAC (running with local echo), and that seemed
to help a little but no guarantees - it may still lock up, but now at a
different place during the transfer.

I've experienced no such problems when dealing with other modems in the
local area, cross-country, etc.  (Of course, haven't been able to find another
Racal Vadic Bell 212 either.)

The USR Autolink 212A documentation is sketchy, to say the least!  No software
commands are documented at all (do any exist?), and only the autoanswer switch
on the back is explained.  Word length and stop bits are settable internally,
but remain at the factory default 8 bits, 2 stop bits.

Any suggestions, ideas, similar experiences?  This is bad news when I can't
upload ANYTHING anymore!  (Still works fine at 300 baud (Bell 202), but ugh.)

Thanks in advance (and sorry for the length).
David Kirschbaum
ABN.ISCAMS@USC-ISID