Where can I buy a linux-friendly laptop?

[phiscock-g851W1bGYuGnS0EtXVNi6w at public.gmane.org]

(This is a bit of a preview to the TLUG talk on December 13th, in which
we'll demonstrate new oscilloscope and signal generator hardware using a
usb-serial device.)

In general, the usb-serial ports appear as /dev/ttyUSB0, /dev/ttyUSB1 and
so on. You simply direct your software to write to that 'serial port' as
it would to any serial port.

Now, when you first plug in a USB-serial adaptor, the system allocates one
of these /dev/ttyUSBx devices to it. This is not like a hardware serial
port, for which the device designation is fixed. The system sees which
/dev/ttyUSBx device is available and allocates that, regardless of which
hardware USB port you plug in to.

Thereafter (if you are lucky ;) the system remembers that particular
device  and tries to allocate the same pseudo-serial port as previously.
Obviously this isn't foolproof - if you have two devices that previously
got /dev/ttyUSB1 and you plug them both in at once, the system gets
confused and you have to select the ports manually.

You can see this at work by running 'dmesg' each time you plug and unplug
the USB-serial cable. It tells you which port it's allocating to the
device. There is also a program 'usbview' which shows how the usb system
is configured.

We figured this out by trial and error, not by reverse engineering code,
so additional or different information may apply...

So to answer William's question, I would bet that you link /dev/modem to
one of these pseudo-serial ports.

Peter

> If anyone used USB modem successfully, what device do I
> link /dev/modem to?
>
> --
> William Park <opengeometry-FFYn/CNdgSA at public.gmane.org>, Toronto, Canada
> ThinFlash: Linux thin-client on USB key (flash) drive
> 	   http://home.eol.ca/~parkw/thinflash.html
> BashDiff: Super Bash shell
> 	  http://freshmeat.net/projects/bashdiff/
> --
> The Toronto Linux Users Group.      Meetings: http://tlug.ss.org
> TLUG requests: Linux topics, No HTML, wrap text below 80 columns
> How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml
>


-- 
Peter Hiscocks
Professor Emeritus,
Electrical and Computer Engineering,
Ryerson University
416-465-3007
www.ee.ryerson.ca/~phiscock

--
The Toronto Linux Users Group.      Meetings: http://tlug.ss.org
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://tlug.ss.org/subscribe.shtml