NOP performs no operation. Its opcode is the same as that
generated by XCHG AX,AX or XCHG EAX,EAX (depending on the
processor mode; see XCHG).
nop
8086 and laterNo Operation
nop | nop r/m16 | nop r/m32 | nop r/m64 | nop imm, reg16, r/m16 | nop imm, reg32, r/m32 | nop imm, reg64, r/m64Loading...
Forms
Every form of nop the assembler accepts, from NASM's own instruction table.
The second column is the processor that introduced the form; a badge marks a form that needs
an extension, that is lockable, or that long mode dropped.
| Form | Since | Notes |
|---|---|---|
| nop | 8086 | |
| nop r/m16 | Pentium Pro | |
| nop r/m32 | Pentium Pro | |
| nop r/m64 | x86-64 | long |
| nop imm, reg16, r/m16 | Pentium Pro | undoc |
| nop imm, reg32, r/m32 | Pentium Pro | undoc |
| nop imm, reg64, r/m64 | x86-64 | longundoc |