Zmodem file transfers via Annex ?

[Stephen G. Simpson]

Can someone tell me why Chuck Forsberg's Zmodem file transfer program
doesn't always work right for PC to Sun transfers via an Annex command
interpreter?

The details are as follows.

Zmodem is a file transfer protocol in wide use on IBM PC bulletin boards,
etc.  It is extremely fast and robust.  The inventor, Chuck Forsberg, also
distributes a version of the program for use on VAX and Unix machines.  It
is available on his bulletin board, Telegodzilla, 503-621-3746 (US phone
number), in the form of a compressed archive called RZSZ.ZOO.

I often dial in to a Sun 3 from home on my IBM PC clone, using a 2400 baud
modem and ProComm communications software (doing VT100 emulation).  The
dial-in goes by way of a gadget called the Annex command interpreter.  I'm
not sure what this Annex thing is.  When I dial in, I get an Annex prompt.
>From there, I have to issue an rlogin command to reach the Sun.

I thought it would be neat to use Zmodem for file transfers.  So, I got
hold of RZSZ.ZOO, extracted the files, uploaded them to an empty directory
on the Sun, and issued the command "make bsd" as per instructions.  The
make went fine and created two executable programs, rz and sz, on the Sun.

The sz program (for sending files) works fine.  I type sz <filename>, then
escape to my local Zmodem on the PC to receive the file.  It's much faster
and smarter than Kermit.

The rz program (for receiving files) doesn't work.  Well, it sometimes
works, maybe once in ten tries.  What usually happens is the following.  I
type rz to receive a file, rz responds and waits to receive the file, then
I escape to my local Zmodem and issue the command to send the file.  The
local Zmodem starts to send the file, but somehow it doesn't get through.
Instead, the connection to the Sun gets broken and my local Zmodem finds
that it is transmitting to the Annex prompt.  The Annex doesn't understand
what Zmodem is throwing at it, so I have no choice but to stop the file
transfer.

It seems that the dial-up connection via the Annex is somehow not
sufficiently transparent.  Somehow Annex seems to be responding to some
escape or control characters that cause it to place the Sun session in the
background, where my local Zmodem can't talk to it.

Does anybody know anything about how Annex works?  Any suggestions on how
to make it more transparent?  Is the Annex really the source of the
problem?  Has anyone had any similar problems with an Annex using other
file transfer protocols?