Project : "WhereTo?"

- Undocumented PC

09/10
Some people think "undocumented" means priviledged information for the selected. A top secret profile buried deep inside some unknown government department. Well it isn't. It isn't even hard to find. It doesn't always require RE like their thoughts. By correctly studying the target, whenever things that aren't clear appears, it should relate to the undocumented. Undocumented is only undocumented but isn't unknown or hidden. Most books in the "undocumented bookstore" not only just gives you undocumented information, but also gives you WAYS to figure out and study undocumented information.

The Undocumented PC, Second edition: A Programmer's Guide to I/O, CPUs, and Fixed Memory Areas by Frank van Gilluwe
IBM did a great favor for Intel and Microsoft. Made a standard called the good ole open platform "IBM PC" and gave all the advantages to them. (although they are having troubles presently) The CPU used for the platform is made and leaded by Intel(and some others like AMD and Cyrix). The OS used for the platform is made and leaded by Microsoft. Everyone knows that. What everyone doesn't know is that they too did LOTS of undocumentation(?). Microsoft is even sued for putting codes to prevent use of other competitors products (Caldera that is). Caldera is famous for its own DOS product, and Open Linux product. It even once distributed their DOS product's source freely. Anyway, what i want to say is that people are giving lots of effort on uncovering the lids.
The first site to get into is the Intel site itself. The fact that you don't know doesn't mean it's undocumented. Most things are at the site, and most documentation are available online(in my favorite format PDF too:). Never underestimate the target itself :P
Intel Secrets is a site maintained by Robert R. Collins which is a rare site covering the Intel CPU underhood(Great job Collins!). Lots of exciting articles and events are prepared. I've read "Protected Mode Basics" article from this site a long time ago which helped me understand things that weren't clearly understood, and for this month, the article came out to the cover page on demand(prabably).
The FAMOUS sourcer product from V-communications, which the author of this book made, is now available for the windows platform too as an addon called Windows Source. If you go to the homepage of this product(which Clive Turvey maintains) you'll not only find the product information but really a lot more jewels like some dump utilities or some aspects of CPUs. It also has a utility to unpack the W4 format that's used for vxds that contains multiple vxds.
Another great x86 information site is Sandpile. This site gives a heap of hardware aspects of the x86 CPU including the upcoming CPUs like Celeron, Xeon, Etc.