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From: glenn@gla-aux.uucp (Glenn Austin)
Newsgroups: comp.sys.mac.comm
Subject: Re: Need help for Zterm file transfer
Message-ID: <0E010021.bztm0h@gla-aux.uucp>
Date: 24 May 91 01:23:10 GMT
Reply-To: glenn%gla-aux.uucp@skinner.cs.uoregon.edu
Organization: The Pit Lane
Lines: 20
X-Mailer: uAccess - Mac Release: 1.0.4a


In article <1991May17.131326.19179@world.std.com>, david@world.std.com (david c spiegelman) writes:
> Note: Zmodem is only slightly faster than XModem-1K

This is not entirely true.  XMODEM-1K still is a half-duplex transmission,
which means that every block must be acknowledged.  ZMODEM only acknowledges
when the transfer is complete, and requests bad blocks as it goes along.
Therefore, a good ZMODEM transfer will have a start send message, then the
file gets sent, and the receiver acknowledges that the transfer was successful.
XMODEM, regardless of flavor, still requires an acknowledgement (positive
OR negative) on every block, which means that the receiver still has to
send that a block was successfully received.

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