86online
Includes Hamarsoft 86BUGS list Online, list of documented and undocumented errors in Intel microprocessors, as well as undocumented instructions.
Art of Assembly Language Programming and HLA
ASM 4 Newbies
for the beginner.
Assembly Language Sources
Instructions of x86
describes Intel processor instructions through 486.
Intel Secrets - What Intel Doesn"t Want You To Know
undocumented features; i.e. bugs. and good assembler programming info.
Linux Assembly
NASM - The Netwide Assembler Project
a free 80x86 assembler.
PC Assembly Language
includes tutorials/demos of programs for newcomers as well as information for advanced programmers.