Date   : Wed, 28 Aug 1985 01:32:00-EDT
From   : ABN.ISCAMS@USC-ISID.ARPA
Subject: TOPS-20 MODEM

NetLandians,

Has anyone else experienced problems with the TOPS-20 file transfer program
MODEM when working through a TAC?

I've tested the latest from SIMTEL20 PD:<CPM.TOPS-20> (I think .315), and
same problem as the one on my host.

Symptoms:  With two different versions of a micro MODEM using Christensen
Protocol (MODEM901 for the Compupro and MDM730 for my Decision I CP/M),
same error:  Incorrect Record # (or was it Header #).  Program never
begins to download.  Watching and capturing the mainframe MODEM packet,
I see with a DUMP two ASCII 01 characters as a leader.

MODEM used to work for me quite a few months ago, but now no luck.
Uploads ("Sends") also fail -- MODEM first returns an ASCII 87H, and then
as I recall, CRs and sometimes a NAK.  No packets move.  Both Checksum
and CRC fail.

I experimented with toggling my TAC Trap (sending the TAC intercept character
twice), but to no avail.

Sure has me bugged!  Would appreciate any help/suggestions.

Regards,
David Kirschbaum
Toad Hall
ABN.ISCAMS@USC-ISID