Free PDF Books:

• Mastering GAS: A Complete Guide to the GNU Assembler, Draft 2.44-6, Ayman Alheraki, 2025, SimplifyCpp.Org 

• Mastering NASM: The Ultimate Guide to Assembly Programming, Draft, Ayman Alheraki, 2025, SimplifyCpp.Org 

• Intel x86-64 Instruction Set Quick Reference, Draft, Ayman Alheraki, 2025, SimplifyCpp.Org

Tutorial:

• Little Puppet's x86 Assembly Language - https://wanker742126.neocities.org/ (In Chinese)

Webs:

• SASM - https://dman95.github.io/SASM/english.html

• SimplifyC++ - https://simplifycpp.org/

• FreeBASIC - https://freebasic.net/

• DJGPP - https://www.delorie.com/djgpp/

• FreeDOS - https://www.freedos.org/

• DOSBox, an x86 emulator with DOS

• DOSBox-X - Accurate DOS emulation for Windows, Linux, macOS, and DOS