Date   : Sun, 12 May 1985 17:35:04 GMT
From   : Chuck Forsberg WA7KGX <caf%omen.uucp@BRL.ARPA>
Subject: Re: MODEM7 PROTOCOL

> A recent file was distributed outlining the CHECKSUM and CRC protocol used
> in the modem7 (CHRISTENSEN) program series.  It was named MODMPROT.003.
> This was great,  as I was working on a modem program to be compatable with
> these protocols.  However,  it was missing the BATCH protocol.
> Is there any documentation on the BATCH protocol commonly used in modem7?
> The file names are transferred as well as the data for each file. 
> This is the most useful protocol for mass transfers between machines.

The MODEM7 batch protocol has many problems besides being tied too closely
to CP/M filenamne conventions, to wit:

     03-Mar-85  19:54:22
 Fm: Ward Christensen 76703,302
 To: Paul Ferrara    70075,252
 
 Modem7 batch was pretty poorly implemented ... complaint was that a
 character-by-character echo was used, which is not a generally recognized
 technique.  It should instead have been something like Forsberg uses with
YAM -
 a block 0 with the filename.  I have had transfers drive me nuts, because the
 other end echoing the outgoing filename causes enough distortion that
it tried,
 and tried, and tried, and tried..   but when it finally made it, the FILE
 itself made it with no hitch.  The weakness was the echoing.

I posted an article recently concerning the availibility of the YMODEM spec
that Ward is writing up for an article in Byte.  If there is sufficient
demand, I will post the file to net.sources or somewhere directly.
-- 
Chuck Forsberg WA7KGX  ..!tektronix!reed!omen!caf
Omen Technology Inc 17505-V NW Sauvie IS RD Portland OR 97231
Voice: 503-621-3406    Modem: 503-621-3746 (Hit CR's for speed detect)