80386 Programmer's Reference Manual -- Opcode NOT

NOT -- One's Complement Negation

OpcodeInstructionClocks DescriptionExample
F6 /2notb r/m8 2/6 Reverse each bit of r/m bytenotb %dl
notb (%ebx,1)
notb m8(%ebx,1)
notb m8(%ebx,%ebp,1)
F7 /2notw r/m16 2/6 Reverse each bit of r/m wordnotw %cx
notw (%ebx,1)
notw (%ebx,2)
notw (%ebx,%ebp,1)
F7 /2notl r/m32 2/6 Reverse each bit of r/m dwordnotl %ecx
notl (%ebx,2)
notl (%ebx,4)
notl (%ebx,%ebp,1)


r/m := NOT r/m;


NOT inverts the operand; every 1 becomes a 0, and vice versa.

Flags Affected


Protected Mode Exceptions

#GP(0) if the result is in a nonwritable segment; #GP(0) for an illegal memory operand effective address in the CS, DS, ES, FS, or GS segments; #SS(0) for an illegal address in the SS segment; #PF(fault-code) for a page fault

Real Address Mode Exceptions

Interrupt 13 if any part of the operand would lie outside of the effective address space from 0 to 0FFFFH

Virtual 8086 Mode Exceptions

Same exceptions as in real-address mode; #PF(fault-code) for a page fault

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