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From: mju@mudos.ann-arbor.mi.us (Marc Unangst)
Newsgroups: comp.dcom.modems
Subject: Re: V.42 questions on T2500 -- How?
Message-ID: <FkFR41w164w@mudos.ann-arbor.mi.us>
Date: 19 Jun 91 00:10:38 GMT
References: <1991Jun17.225901.10900@coplex.uucp>
Organization: The Programmer's Pit Stop, +1 313 665 2832
Lines: 34

dean@coplex.uucp (Dean Brooks) writes:
> 1)  How do I get V.42/V.42bis to be automatically recognized?

For V.42 operation, set S106=1 (V.42 auto-detect) and S97=1 (V.42
enable).  For V.42bis operation on top of V.42 operation, set S98 to
1, 2, or 3 (depending on whether you want to compress transmitted
data, received data, or both, respectively).

> 2)  What in the world is LAP-M?

Link Access Protocol for Modems, aka V.42 and V.42bis.

> 3)  Is any of this stuff synonymous to MNP-5?

Sort of.  V.42 is the CCITT equivalent of MNP-4 (i.e., it does error
detection and correction), but is *not* the same protocol.  V.42bis is
the CCITT equivalent of MNP-5 (i.e., it does realtime compression of
data), but is *not* the same protocol (the most important feature over
MNP-5 is that it does not attempt to compress already-compressed data;
under MNP-5, already-compressed data can expand to 120% of its
original size after "compression").  You want to use V.42 and V.42bis
over MNP-4 and MNP-5 whenever possible, since they're generally faster
and more robust than their MNP counterparts.

> 4)  Help!

All of this is explained nicely in the release notes for the GF7.00
T2500 ROMs.  If you have a ROM revision earlier than GF7.00, V.42 and
V.42bis aren't supported, and you'll need to get new ROMs from Telebit.

--
Marc Unangst               |
mju@mudos.ann-arbor.mi.us  | "Bus error: passengers dumped"
...!hela!mudos!mju         |