From: John Kim (kim_at_stormhaven.org)
Date: Mon Apr 26 1999 - 13:56:41 EDT
On Sat, 24 Apr 1999, STeve Andre' wrote:
>
> Can someone explain what the MWave modem is? I have a 1451 i series
> TP and wonder if my modem is that kind? tnx
> STeve
MWave is sort of the predecessor to WinModems. All modems
have an A/D and D/A (analog-to-digital, digital-to-analog)
convertor in them which coverts from/to the analog waveform on
the telephone line to/from the 0s and 1s computer use. This is
not a trivial task, and up until the early '90s was almost
always done via hardware. The drawback of doing it in
hardware of course is that once you mold the hardware, that's
what it does for life.
In the early 1990s, specialized floating point processors
(DSPs, digital signal processors) designed specifically for
A/D and D/A processing in software became fast enough that it
could handle the A/D and D/A necessary in a modem (14.4 kbps I
think was state of the art then). IBM came up with the clever
idea of putting one of these DSPs in their Thinkpads to
operate as a modem. The advantage being that since the
hardware is generic, you can reprogram what it does via
software. When a new modem standard (e.g. 28.8) comes out,
you simply reprogram the DSP and what used to be a 14.4 modem
is now a 28.8 modem. IBM dubbed this feature "MWave" (probably
because the other major A/D / D/A component in computers is
the sound input/output - or multimedia).
Anyways, the impression I got was that IBM was having
difficulty releasing up-to-date software drivers for the MWave
to match the rapid advancements in hardware modems. This was
probably coupled with the early MWave DSPs simply not having
enough horsepower to do both 28.8 and multimedia sound at the
same time. And apparently MWave was designed around Windows
so supporting it under other OSes was problematic (other
audio/modem DSPs like the one found on the TP701 do not have
this problem). It was a good idea, but companies could put
out new modem hardware faster than IBM could put out new DSP
software.
WinModems use the same concept, but use the main CPU instead
of a DSP (yes, CPUs have gotten that fast). That's why you
generally want to avoid them unless you don't mind the CPU hit
and an extra 100-200 ms latency (and, as the name implies,
they can only be used under Windows). Because they use the
CPU instead of integrated A/D and D/A convertors, they are
usually about $50 cheaper.
I have no idea what type of modem the 1451i uses. IBM has had
a bad history of releasing timely updates for their MWave (I
don't think 28.8 was available for nearly a year after 28.8
modems started showing up in stores), and Linux support has
been spotty-nonexistent, so I have as a rule avoided TPs with
MWave. But even if you do have one, you can always buy a
PCMCIA/Cardbus modem and use it in lieu of the MWave.
-- John H. Kim kim_at_stormhaven.org
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