modem education

[Bruce Marshall]

On Sunday 04 June 2006 09:36, Bob Hemus wrote:
> O.K. fellas, I hope this stupidity is not an indication getting older slows
> you down, on the other hand I'd hate to think I was ths stupid all my life?
> But, I thought a modem that ran boh Linux and M$ was just a kind of switch
> with embedded software.  I thought embedded software was burned-in?  I
> googled Linux -> modems -> drivers @ google.com/linux and eventually ended
> up with "ltmodem-kv_2.4.20_4GB-8.26a9-1.i3866.rpm and one for a Debian
> distro.  It was from ActionTec, which is what my modem is and it lsted
> drivers for OS2, Win 3.1 to XP. but nuthin' for my modem which this is
> specifically for the Lucent chip I have??  In the ActionTec Manual for ths
> file it describes how to set up a /dev/ttySx and a /dev/c?ua? (didn't copy
> it down and it won't display on XP), but says after kennel 2.2 that became
> obsolete?
> Would some gracious member of this outstanding group of Ladies&Gentlemen
> give me a hint to educate myself about the functions of modems?  Please?
> Thanks, Bob

A modem takes digital output from your computer and turns it into sounds 
(analog data) which it then sends down a phone line.   The modem at the other 
end takes the sounds it hears and turns them back into digital data which it 
passes to whoever is at the other end.   And the reverse process also takes 
place so that two computers can 'talk' to each other over a normal phone 
line.

Since it is software (really firmware if it is inside the modem proper) that 
is dealing with the sounds to do the translation to digital and vice versa, 
someone decided they could save a $20 chip (probably $3 these days) by 
eliminating that chip and letting a 'driver' on the computer itself handle 
the software tasks.  Thus, for what we call a 'Winmodem', you are really 
looking at only half a modem.  There is a chip or more missing and the 
function of that chip has to be done by the main CPU in your machine.  And 
you need a driver for the modem to do that.

And since most drivers in existence are written for MS Windows, you may not be 
able to find a driver to do the same thing on Linux.

So a modem is not a switch....  and it knows not really which OS you are 
running, as long as there is a driver (if needed) that will make the modem 
work like it is supposed to.

I think I would be safe in saying the *all* external modems are what we 
call 'real' modems.  That is, they do not need a specific driver to make them 
function.   *Some* plug-in PC cards are real modems....  they have all the 
functions on-board.  So when you need to buy a modem for linux, you are best 
to buy a real modem....   not one that needs a driver.

Now...  there are a lot of Winmodems that are supported on Linux, and in my 
Thinkpad X30 which uses a Smartlink Windmodem and used to have a driver for 
it, there is no module for it for SuSE 10.1, the latest release.  But in a 
day or so of looking around...  I found a workaround that uses an ALSA driver 
which does the modem function.  (we're dealing with sounds, remember?)  So in 
your case you might find a driver for your Winmodem...  or maybe an ALSA 
driver for it.

We would need to know the chipset.  I think you said it was Lucent which is a 
pretty well support chipset if I recall from when I used to use one.