The Maverick Operating System
NeoDOS
FreeDOS

Paul Hsieh's x86 Asm Page
Ralf Brown's [DOS] Interrupt List DOS/Windows disassemblers
Alin Consatin's Most Useful Links
File System Programming The Bochs IA32 emulator
FAT32 resource page
fat_paper.pdf
Extensible Firmware Interface
Description of FAT32