Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!zephyr.ens.tek.com!tektronix!psueea!parsely!escargot!chrisb
From: chrisb@escargot.UUCP (Chris Bradley)
Newsgroups: comp.mail.uucp
Subject: Zmodem added to UUCP
Message-ID: <3602@escargot.UUCP>
Date: 23 Sep 89 22:05:24 GMT
Reply-To: chrisb@escargot.UUCP (Chris Bradley)
Distribution: usa
Organization: Coredump Central
Lines: 91

Greetings again everyone!

   I have spoken briefly with Chuck Forsberg himself, and he says that there
isn't a Zmodem standard for UUCP. I would like to elect myself as "Head of
the project", so to speak. I have come up with, what I believe to be, a
very good extension to Zmodem. Not only is it versatile, it's very simple to
understand. I would like to open it for debate to the net, therefore, I'm
posting the protocol description. Please feel free to e-mail or post responses.
Chances are there is something I have overlooked, but if you find something,
please let me know.

------

             Zmodem Protocol Extension To UUCP Startup Sequence
	     --------------------------------------------------

    This file describes the zmodem extension to the UUCP protocol. UUCP Is
started up as a normal UUCP session with the addition of the "z" to the list. 

Sender                                           Receiver
------                                           --------
	                       <-------          \020Shere\0

\020S<mastername> <sw>\0       ------->

                               <-------          \020ROK\0
			       
			       <-------          \020PgXyz\0  (1)

\020Uz\0                       ------->

			       <-------          ZACK
				  or
                               <-------          ZCAN, ZCAN, ZCAN, ZCAN, ZCAN

(1) Capital X, lower case y, and z have been reserved for Xmodem, Ymodem,
    and Zmodem respectively.

At this point, the receiver can back out of Zmodem if it can't link to its
Zmodem program. Otherwise, it tells the sender to go ahead and sent the files
in Zmodem batch mode.

ZRQINIT                        ------->
	          (Normal Zmodem batch takes place)

ZFIN                           ------->          

			       <-------          ZFIN

OO                             ------->

The "OO" is a Zmodem "Over And Out" standard. It isn't a requirement that the
receiver hear the two "OO"'s.

Once the initial transfer has completed, both machines know that it's time to
turn the line around. Therefore, the receiving computer, below, says "Let's
use the Zmodem protocol".

                              <-------          \020Uz\0

ZACK                           ------->
				  or
ZCAN, ZCAN, ZCAN, ZCAN, ZCAN   ------->

Here again, it gives the sender the opportunity to cancel out if it can't
link to the Zmodem receive program.

Upon receipt of five ZCAN's, the two systems will disconnect.

			       <-------          ZRQINIT
                 (Normal Zmodem batch takes place)
			       <-------          ZFIN

ZFIN                           ------->

			       <-------          OO
                         (Systems disconnect)

Not much more to be said. Fairly self-explanatory.

I kept in mind to keep the above exchange as simple as possible to keep
programming time and complexity to a minimum.

-------

Comments anyone?

-->Chris

UUCP: ..tektronix!tessi!escargot!chrisb     "I didn't like the Mercury Sable,
Phone: (503) 644-3585 (Call anytime!)       So I bought a Ford Taurus instead!"