Path: utzoo!utgpu!cunews!bnrgate!bigsur!bnr-rsc!bcarh188!lalibert
From: lalibert@bcarh188.bnr.ca (Luc Laliberte)
Newsgroups: comp.sys.ibm.pc
Subject: Re: what is the quickest (most efficient?) File xfer protocol?
Summary: Don't use ZMODEM on noisy lines
Message-ID: <3765@bnr-rsc.UUCP>
Date: 29 Nov 90 17:36:31 GMT
References: <33558@netnews.upenn.edu> <aRHDT2w163w@cybrspc>
Sender: news@bnr-rsc.UUCP
Reply-To: lalibert@bcarh188.UUCP ()
Organization: BNR Ottawa, Canada
Lines: 13

My brother once set up a download using ZMODEM.  He came back an hour
later expecting to be logged out.  (Autologout when download completed.)
But the modem was still chugging along with a block size of 1 byte!
He quickly brok out and used XMODEM.  Turns out if ZMODEM feels too many
errors are occuring it decreases the block size to reduce retransmission
time.  But if the trouble clears up, it doesn't increase the size.
What likely happened is the phone got picked up, giving mega noise, and
dropping the block size.
Otherwise ZMODEM is exceptionally fast, unless you are using MNP5 as well.
(The two blocking processes can interfere with each other) in which case
there's a YMODEM varient for that reason.  SEALINK and TELELINK also work
well if Y or ZMODEM are unavailable.