Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.dcom.modems
Subject: Re: Modem for Laptop
Summary: host software based MNP
Message-ID: <1711@neoucom.UUCP>
Date: 6 Sep 89 15:03:33 GMT
References: <4317@emory.mathcs.emory.edu>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 22


One way to achieve MNP connectivity on a laptop computer is to use
a host (i.e. the laptop) based MNP protocol realization.  I use a
Tandy 1400 with a Tandy, A.K.A. Ventel, 1200 bps modem.  The Tandy
modem does have an adaptive eqaulizer that allows it to handle many
poor quality lines, but there are occasions where there are noise
impairments other than impedance-mismatch echoes.  In such cases I
switch from using the Procomm terminal emulator program over to
Mirror III with the MNP add-in module.   The Mirror module supports
MNP level 3.  The host-based MNP seems slower than the AT&T 2224CEO
modem that I use that has built-in MNP.  There seems to be about a
two second pause as the MNP packets are assembled with the
software, while the modem based MNP seems to require about half
that amount of time.  The software lag is not CPU bound, as I tried
running on an IBM model 80 with an IBM modem and saw similar
delays.  None the less, if you need error correction and have to
live with a certian modem, the MIrror III MNP add-in (~$40US for
the add-in plus whatever Mirror III costs these days) is a
reasonably inexpesive and reliable solution.  Any generic 1200 or
2400 bps modem seems to be acceptible for use with the software.

Bill