[ltp] ThinkPad Modem Madness

Thomas Hood linux-thinkpad@linux-thinkpad.org
06 Oct 2002 09:00:50 +0200


On Sun, 2002-10-06 at 05:16, JC WOODWARD wrote:
> Winmodems are DSP modems.
> 
> DSP modem - a modem that relies on Digital Signal Processing software.
> See Winmodem.

These are unorthodox definitions.  In my experience, the
acronym "DSP" means "digital signal processor"; so a DSP modem
is a modem with a hardware-implemented digital signal processor.

Some winmodems have the DSP (hardware) but no (hardware) UART.
The driver emulates the UART.  Such modems perform about as
well as full-fledged modems, if not better.  The Mwave/ACP
modem on the ThinkPad 600 and 600E and the Lucent LT modem
on the 600X are of this kind.

Some winmodems also lack a (hardware) DSP.  The driver does
the digital signal processing, thus severely taxing the
host CPU.  These are the ones to avoid.

> Linmodem - a winmodem for which driver software has been written to
> run under Linux.  Winmodem manufacturers write drivers for Windows,
> but drivers for Linux often don't exist.

... until they are written by Linux hackers ...

> LTModem - one of the several models of winmodems manufactured by
> Lucent Technologies (now Agere Systems).  The excellent LTModem Linux
> driver works with all the LTModems.  Several Thinkpad models,
> including the 390X, TP570E, A2, T2, X20 and 600X use LTModems.
> 
> Mwave (or ACP) modem - a winmodem used on several Thinkpad models,
> including the 600 and 600E and 770. Linux drivers are available from
> IBM with updates as recently as 7/18/02. I don't know if they work.

They work very well.

The rest of your message was a useful summary.  Thanks.

--
Thomas Hood


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