Date   : Fri, 16 Nov 1990 02:59:31 GMT
From   : bbn.com!gonzalez@eddie.mit.edu (Jim Gonzalez)
Subject: Anyone Built and Used CMODEM?

Now that I have the HSIO (many thanks to those who responded) working, my 
attention has turned to terminal emulation and file transfer software.  

Included with the commercial distribution of BDS C is the source for a 
program called CMODEM.  It claims to implement the MODEM7 protocol, which
Jay Sage told me is also known as XMODEM.

I've successfully compiled and linked CMODEM, and the terminal emulation
component seems to work well enough (I'm using it to enter this posting,
for example).

When I attempt to transfer files from various boards that support nMODEM
(where n is X,Y, or Z), I get nothing.  I tell the remote host that I want
to do an XMODEM transfer, escape to CMODEM's command level and tell it to
receive the file.  It sits there doing retries, showing no errors or
received packets.  Aborting the transfer from my end, using ^X, and
returning to terminal mode shows that the remote host received the abort
signal (a pass-through of the ^X I typed, according to the source) and 
is waiting for me at command level.

Has anyone here successfully built and used CMODEM?  Perhaps I'm specifying
the wrong protocol to the remote host (Jay indicated that specifying XMODEM
*without* batch mode or 1K mode was the way to go; I tried 128 and 1K, CRC
and checksum in various combinations).  

                               -Jim.