If you are interested in development kit that this project uses, visit:
1. http://www.delorie/djgpp/ - GNU project, ported to DOS
2. http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/index.html - GNU project, ported to OS/2
3. http://sourceware.cygnus.com/cygwin - GNU project, ported to Win32
4. http://www.leo.org/pub/comp/os/os2/leo/gnu/emx+gcc/rsxnt/index.html - another GNU project for Win32 EMX based.

Documentation and instruction sets of processor families can be found at the sites of their creators:
http://developer.intel.com/design/PentiumIII/manuals
http://www.amd.com/support/techdocdir.html
http://www.cyrix.com/products

The x86/MSDOS Interrupt List and much more:
http://www.pobox.com/~ralf

Other CPU programming guides:
sandpile.org, x86.org, x86 bugs

Information about character sets can be found at the site Mr. Czyborra:
http://www.czybora.com

Information about internal structures of binary files can be found at:
http://www.wotsit.org