🚀 go-pugleaf

In article <1991Apr16.110136.6239@wam.umd.edu> bjahn@wam.umd.edu (Guess ???     ) writes:
>In general, what is the standard in 9600 modems, and is there much difference
>in int/ext modems beside personal preference?

Most 9600 bps modems today are V.42bis.  External/internal is really a
matter of personal choice.

>	What is difference between v32, v32.bis, v42, v42.bis and MNP5?

The MNP (Microcom Networking Protocol) is a protocol which is available
on various levels (1-10).  Each level has the benefits of its predecessors
plus some added features.  All levels incorporate error correction for
error-free transmission.
MNP-4 is a slight improvement over MNP-3, which strips the start and stop
bits before transmitting data.  The modem on the other end adds them before
relaying the data to the serial port.  On the average this will increase
throughput by a concrete 20% or so.  By concrete I mean that this value
doesn't change and is independent of the type of data being transmitted.
MNP-5 also incorporates data compression which can increase throughput
by up to 100%, depending on the type of data transmitted.  Text data will
be transmitted approximately 2x faster than if you were using MNP-4.
Compressed data (i.e., .ZIP files) will take _longer_ to transmit since
the MNP-5 protocol is 'dumb' in that it attempts to compress all of the
outgoing data.
CCITT V.32 is a protocol designed for 9600 bps modems that doesn't offer
the error control and data compression that is demanded by most of today's
users.
CCITT V.42 uses the LAPM (Link Access Procedure for Modems) error control
protocol to insure that transmissions are error-free.
CCITT V.42bis adds data compression that yields up to a 4x increase in
throughput.  Unlike MNP-5, V.42bis is a 'smart' protocol which only
compresses data when the resulting block is smaller.  Therefore, there
is no decrease in throughput if compressed data is transmitted.

>What would be a good buy for a modem that won't be outdated or will be off
>standard in the future?

Before true standards such as CCITT V.32 and V.42, 9600 bps modems used
different protcols which made communicating a nightmare.  You had to
buy modems from the same manufacturer if you wanted to be sure that they
would communicate effectively.
However, since the introduction of CCITT standards, this problem has
reduced in magnitude.
So I would recommend that you buy a modem which offers V.42bis, V.32
and MNP-5.  Although MNP-5 is an inferior protocol which will be
obsoleted soon by V.42bis, many sites today offer only MNP-5 and
not V.42.  And MNP-5 is better than nothing.

I admit that I know very little about HST modems.  I believe they
offer 14Kbps connections, but I may be wrong.

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