Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!snorkelwacker!mit-eddie!mit-amt!mjkobb
From: mjkobb@mit-amt.MEDIA.MIT.EDU (Michael J Kobb)
Newsgroups: comp.sys.mac
Subject: Re: MNP-5 with Microphone II
Summary: I'm not sure I follow..
Keywords: modem, MNP-5
Message-ID: <1765@mit-amt.MEDIA.MIT.EDU>
Date: 5 Mar 90 09:59:50 GMT
References: <6408.25e516f9@pbs.uucp> <16381@well.sf.ca.us> <00932CDA.BB401C20@uclapp.physics.ucla.edu> <1967@husc6.harvard.edu> <16506@well.sf.ca.us> <1990Mar4.203716.12505@agate.berkeley.edu>
Reply-To: mjkobb@media-lab.media.mit.edu (Michael J Kobb)
Organization: MIT Media Lab, Cambridge MA
Lines: 40

In article <1990Mar4.203716.12505@agate.berkeley.edu> c60a-3hu@e260-1g (Calvin Cheng) writes:
>
>I've just got thss Everex 24E+ 2400bps MNP-5 modem and am thinking
>of accessing the modem in the MNP-5 mode t connect to campus with a
>computer- modem speed of 19200bps. It seems that alot of special AT
>commands have to be sent to the modem before this can be done. I've
>got little luck fiddling with ZTerm 0.85. Since I'm seriously
>thinking of using Microphone II for communications, I want to be
>absolutely sure if this can be done cleanly (and not after some
>dirty kludges) with Mic II 3.0. By the way, as I'm unfamiliarwith
>the MNP-5 standard, could somebody please enlighten me on the
>protcal and the level of standardization among MNP-5 modems (ie
>what modem is mine equivalent to)?

Hiya,

  First of all, why the 19.2?  With MNP-5 compression, you will be running at
4800 BPS effective throughput on the modems, assuming a good connection.
Using a computer<->modem speed much faster than that doesn't really get you
much.  9600 might be worth it just so that the modem never, ever has to wait
for anything....

  Second, the AT commands aren't any too nasty.  You'll notice that ZTerm has
the "Modem String" option, or somesuch.  Why not just set that to the
apropriate settings.  Or, you could do what I do which is to map a function
key in ZTerm (using MasterStrokes) to the apropriate string.  Then I can just
zap it out to the modem whenever.  You can also define multiple strings for
different purposes.

  As for the protocol, in 100 words or less, it uses some form of checksum for
error detection, and uses a data compression algorithm which basically removes
superfluous leading zeros from bytes and reinserts them on the other end (I
think, from the discussion I had with the algorithm's designer... it was
awhile ago).

  I've never used Microphone II 3.0, since I found their upgrade fee to be
utterly outrageous, and didn't really like the program much in the first
place.  ZTerm does everything I need, except really good vt100.  I'm hoping...

--Mike