[TriLUG] how do USB disks and USB wifi cards work?

[Joseph Mack NA3T]

I have assumed that a USB disk worked something like this

o the USB driver arranged for the USB transport hardware to 
deliver whatever was at the end of the USB cable to the OS. 
The OS saw a disk and loaded the disk driver code. The OS 
talked to the disk without knowing (or maybe not caring) 
that an intermediate layer was carrying the bits back and 
forth to the disk.

This was fine till I wondered if a USB wifi card worked the 
same way. I assume that the manufacturers use their standard 
wifi hardware and instead of using a PCI or pcmcia 
interface, they put in a usb interface. Presumably then the 
standard Linux usb code would handle the usb link, and the 
OS would use the standard wifi driver for that piece of wifi 
hardware.

However I went to the madwifi webpage to find that they 
don't support USB wifi cards (because of difficulties 
writing the code). Presumably my model of how USB connected 
devices work is wrong.

Anyone fill me in?

Thanks Joe

-- 
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!