Date   : Sat, 03 Dec 1983 04:39:00 EST
From   : revc%CCVAX@nosc
Subject: Tops-20 modem.

Note: The following assumes (ass.u.me) that the tops modem
program that you are refering to uses the Ward Christianson
Modem2 protocol.  If not, then all bets are off.


Insure that the XON/XOFF protocol is disabled on the entire
link.  We ran into that same problem here using the LocalNet.
It turns out that the header for block 19 contains a ^S and
17 contains ^Q.  This caused us to lock up on block 18, with
the same symptoms that you reported at block 16.  Could your
XOFF value have been changed to 11H, the header value for block
17?

I do not believe that speed (1200) has anything to do with your
problem, as the maximum buffer size that you need is one block (128)
and a bit (header and trailer), as the next block will not be sent 
without an ACK, which is generated by Modem, not the tops 20.

The only problems we have ever had with speed, is loss of sync
when printing an error message to the screen on a micro while the
header is being sent, an simple timeouts on the vax due to heavy
system loading.

Bob Van Cleef
Computer Sciences Corporation
Naval Ocean Systems Center
San Diego, CA

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