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From: tnixon@hsfmsh.UUCP (Toby Nixon)
Newsgroups: comp.dcom.modems
Subject: Re: V.42bis
Message-ID: <3430@hsfmsh.UUCP>
Date: 5 Jul 90 15:22:08 GMT
Sender: daemon@hsfmsh.UUCP
Organization: Hayes Microcomputer Products, Inc.  Norcross, Georgia
Lines: 25

In article <1990Jul04.130105.3502@nstar.uucp>, Larry Snyder asks:

- Is LAMP a DUPLEX protocol - or a compression form?  

Well, George has the acronym wrong: the error control protocol 
defined in CCITT Recommendation V.42 is "LAPM", which stands for 
"Link Access Procedure for Modems".  It is NOT a data compression 
scheme, but an error-control protocol.  The CCITT data compression 
standard is "V.42 bis"; the compression technique itself is a form 
of Lempel-Ziv-Welch compression, extended for real-time modem 
operation with enhancements designed at British Telecom and Hayes.  
To answer your question, LAPM is a duplex protocol, and V.42bis is 
designed to compress in both directions simultaneous when run on top 
of LAPM.

	-- Toby

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