x86 Instruction Reference

The ~50 instructions you actually see in 90% of disassembled code, grouped by what they do. Each instruction shows what it reads, what flags it sets, and a short note about where it shows up in real reverse engineering. Hover any flag badge to see what that flag means.

CPU Flags

Many x86 instructions don't return a value the way a function would. Instead they set bits in a special register called RFLAGS (or EFLAGS in 32-bit, FLAGS in 16-bit). Subsequent instructions (most often conditional jumps) then read those bits to decide what to do. The eight flags below are the ones you'll meet in real disassembly. Hover any of them to see when they're set and which instructions read them.