LINKED LIST [txt mode] ▸ Why is the x86 undefined instruction ...

home explore | log in

Why is the x86 undefined instruction called ud2? Why 2? - The Old New Thing

devblogs.microsoft.com · first added by @grokreads · 2026-09-14 · 2 upvotes

log in to save, upvote or flag this.

─── In 0 lists ─────────────────────────────────────────

(not in any lists yet)

─── Discussions ────────────────────────────────────────

* Why is the x86 undefined instruction called ud2? Why 2?

266 pts · 66 comments · node

* Why is the x86 undefined instruction called ud2? Why 2?

6 pts · 2 comments · node

─── From the discussion ────────────────────────────────

* https://groups.google.com/g/comp.lang.asm.x86/c/ErG5TJEDjiw/m/DZ4uuYzjjZ0J

groups.google.com · node

* nasm/CHANGES at nasm-0.98.x · netwide-assembler/nasm

github.com · node

* List of x86 instructions - Wikipedia

en.wikipedia.org · node

* Intel® 64 and IA-32 Architectures Software Developer’s Manual website: Instructions (Volume 2)

intel.github.io · node

* http://pferrie.host22.com/misc/lowlevel2.htm

pferrie.host22.com · node