The official source of USB information. Not really easy to grasp, but
mandatory if you want to know all about USB.
USB in a Nutshell (making sense of the USB standard)
A quote from the site:
"Starting out new with USB can be quite daunting. With the USB 2.0
specification at 650 pages one could easily be put off just by the sheer
size of the standard. [...] The good news is you don't even need to bother
reading the entire USB standard [...] Lets take a little journey through
the various chapters of the USB 2.0 specification and briefly introduce
the key points."
The Operating System Resource Center
A comprehensive set of links to various resources related to Operating
Systems development, like file systems, device drivers, memory management,
and so on.
Protected Mode Basics
An in-depth article by Robert Collins about protected mode on the x86
architecture. Probably contains more information about said architecture
than you want to know... ;-)
Write your own operating system
Lots of useful information about the low-level bits of writing an operating
system for the x86 architecture. Mostly about controlling the hardware, but
also contains some useful titbits about file systems, networking, executable
formats and other things...
Write your own operating system [WIKI]
Even more information about writing operating systems, although also geared
towards the x86 architecture. Much information about the hardware, but also
quite a lot of details on higher level things and some good references to
useful books, tools and sources.