MNP Modems
Richard,
The benefits of an MNP modem are many, especially if your phone line is
subject to occasional fits of noise.
Make sure that the MNP error correction is done in hardware, the software
versions of this mode do not do it justice.
Although an MNP modem must be connected to your computer at a baud rate
that is higher (usually two or four times) than the connection rate in
order to have a gain in throughput, it will never achieve the 4800bps rate
that the marketroids like to claim for these things.
The two most common levels of MNP today are 4 and 5. Level 4 provides a
solid 17% perfomance gain by stripping the start and stop bit for each
character transmitted. Level 5 adds data compression to the picture, for
text only transfers, the performance gain is incredible. But for most file
transfers with a protocol such as ZMODEM, it can actually degrade
throughput due to archived binary files usually being the object of the
transfer.
Average speeds of an MNP level 4 ZMODEM transfer can range between
250-270cps, depending on the data in the file.
Text will look somewhat choppy in the way it is received with level 4.
With level 5, a full screen of text can sometimes pop up, but it too will
usually have a choppy look to it. Some people find it a bit disturbing to
look at at first, but the lack of "modem puke" (noise) far outweighs the
disjointed appearence of text output.
An MNP modem requires CTS/RTS (7 wire) handshake in order to work without
data loss, I don't think games that have a modem mode are sophisticated
enough to provide this, although I may be wrong on this, I'm not a gamer.
As for actual brands, I can recommend the MultiTech 224EH, although it is
a good deal more expensive than most others available today, it is one
solid product.
If your budget allows and you plan on doing a decent amount of long
distance calling, I'd have to say the 14.4kbps HST is the most economical
modem in the long run. Not only does it fall back to standard 2400bps with
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