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From: leonardr@svc.portal.com (Leonard Rosenthol)
Newsgroups: comp.dcom.modems
Subject: Re: How to increase throughput on 9600 bps modem?
Message-ID: <1990Dec14.174237.1708@svc.portal.com>
Date: 14 Dec 90 17:42:37 GMT
References: <9PF^W}#@ads.com> <17@ghost.UUCP>
Sender: news@svc.portal.com
Reply-To: leonardr@svc.portal.com (Leonard Rosenthol)
Organization: Software Ventures Corporation.
Lines: 27

In article <17@ghost.UUCP>, kianusch@ghost.UUCP (Kianusch Sayah-Karadji)
writes:
> ... if you modems have compression mode don't use Zmodem
> (use Y/X modem instead) ... if you do want to use Zmodem ... turn modem
> compression of and use only local error correction... same thing with
> compressed files, (zoo, compress, zip, ...) dont use Zmodem or Modem
> compression at all.
> 
> The reason is that each of those try compress the data... 
> 
	THIS INFORMATION IS INCORRECT!!  It is true that you do not want
to send compressed files across a modem on which compression is enabled -
but the protocol doesn't make a difference, especially ZMODEM.  All of the
current Macintosh ZMODEM implementations, and most of the PC/UNIX, etc. DO
NOT support compression!  The ZMODEM spec does provide hooks for RLE
compression, but Forsberg never recommended implementation due to lack of
standardization.  His new ZMODEM-90 (Moby-Turbo) provides for a standard
RLE compression across ZMODEM implemenation, so some newer products may offer
it as an option, but you will not yet find one on the Mac or UNIX (rzsz).
And to my knowledge, only dsz on the PC has the ZMODEM-90 extentions.

--
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+ Leonard Rosenthol              | Internet: leonardr@sv.portal.com  +
+ Software Ventures              | GEnie:    MACgician               +
+ MicroPhone II Development Team | AOL:      MACgician1              +
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