Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!decuac!netsys!faatcrl!jimb
From: jimb@faatcrl.UUCP (Jim Burwell)
Newsgroups: comp.mail.uucp
Subject: Re: New UUCP Protocol (was: Re: Zmodem added to UUCP)
Message-ID: <1042@faatcrl.UUCP>
Date: 14 Oct 89 06:23:44 GMT
References: <672.2530C0D4@mudos.ann-arbor.mi.us> <690.25315ee6@simpact.com> <839@omen.UUCP>
Organization: FAA Technical Center, Atlantic City NJ
Lines: 44

caf@omen.UUCP (Chuck Forsberg) writes:


>Perhaps this has changed in newer models, but the TrailBlazers I have
>turn the line around when spoofing UUCP.

Do you have uucp spoofing mode turned on ?  On a Telebit T2500, you would
set s111 to 30 for the 'g' protocol.

>To answer a previous question about ZMODEM framing overhead I must give
>some basics of ZMODEM.  When ZMODEM is in full streaming operation, the
>data in a file is sent as a ZDATA header followed by 0 or more data
>subpackets whose lengths are 0-1024 bytes.  So in a 16K file with no
>errors we could have one ZDATA header (about 11 bytes if CRC-32 is used)
>and 16 data subpackets.  Each data subpacket is terminated by two bytes
>and CRC.  In a long file sent with CRC-32, the framing overhead approaches
>6/1024, or about 0.6 per cent.

Yow!  I assumed that each 1k packet had that long control string embedded
in it  ("**B############", etc).  Zmodem is even more efficient than I thought!
One day I'll sit down and read my zmodem description textfile thouroughly :-).

>To support network operations, ZMODEM protects XON, XOFF, and DLE in both
>parities.  This adds just under 3 per cent overhead on typical compressed
>files.

One of the many reasons I use Zmodem every day.  Great prot. Chuck!

CU,

-- 
+------------------------------------------------+--------------------------+
|          James S. Burwell                      |                          |
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