I-Modem protocol - test-drb@ccmp.vtda.org

6 Nov 2001

...
  What I am looking for is the specs needed to write an
implimentation of 
 it. I have a system that can only send files via i-modem, and I want to 
 write a new program to talk to the server. Right now I use Procomm Plus 
 1.1b since it is the only application that I have found that supports 
 imodem. I would like to write a custom front end to the system, so I can 
 make access safer, easier, and more automated.

 If anyone has specs, or source code for imodem they can send me, it woud 
 be very helpful. 
This really is a tough one- it's possible some of the stand-alone
transfer protocol modules might have implemented it, but didn't
include any info in the docs... as a search yielded no more than
you found.

Two thoughts: The WildCat BBS has (IIRC) the IMODEM protocol; contact
the WildCat prople and ask them for just that single module (they
want about $800 for the BBS source code).

Secondly... reverse engineering by setting up a second PC running
any terminal emulator, try sending a file from the IMODEM-only device,
surely it will respond to ACK/NAK... try NAKing some packets, ACK some
others, dump the result, start hacking...

Be sure to filter out the ACKs/NAKs you're sending from the
dump, no need to confuse yourself...

hth,
-dq