Date   : Tue, 21 Apr 1987 00:22:44 CST
From   : jdb@ncsc.ARPA (Brown)
Subject: MEX Batch mode solved

Well, it looks like I wasn't the only one having trouble with batch mode in 
MEX.  Thanks to Steve Grandi at noao.arpa for the solution.

As he (and others) said, MEX uses the XMODEM-BATCH protocol, not the
YMODEM-BATCH protocol. (here I'm only talking about the public domain
version of MEX, version 1.14, I hear the commercial version supports both)
XMODEM-BATCH is a kludgy implementation of a batch protocol, but it works.
YMODEM-BATCH is a more 'elegant' implementation which allows passing of 
much more info about the file and is not restricted to the CP/M notion
of what a file name should look like.  For documentation on the two
protocols, look under pd:<misc.protocols> at simtel20. There is 
documentation on XMODEM-BATCH and a more generic description of both
xmodem and ymodem (don't remember the exact names noe, but they are obvious
if you can get a directory listing).

Steve also provided a copy of his 'xmodem' program which supports x/ymodem
batch protocols, 1K/128 packets, and CRC/checksum in any combination.  As 
it turned out, I had to modify the batch send code to work with my C128.
The time required to create the new file was longer than xmodem wanted
to wait around for the NAK/C following the file name transfer (5 seconds),
so xmodem was giving up before MEX (on a C128) got back to the transfer.

So, the answer is, if you need to talk batch using MEX to UNIX running 
4.2/4.3BSD, Steve's xmodem will do the job.  If you are using a C128,
the file send.c which is part of his package, needs to be modified to
wait longer for the C/NAK following the name transfer.

If anyone has any questions about what is needed, let me know.

david brown
jdb@ncsc.arpa