Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1603

NOP—No Operation
Opcode
90
Description
Performs no operation. This instruction is a one-byte instruction that takes up space in
the instruction stream but does not affect the machine context, except the EIP register.
The NOP instruction performs no operation, no registers are accessed and no
faults are generated.
Flags Affected
None.
Exceptions (All Operating Modes)
None.
Volume 4: Base IA-32 Instruction Reference
Instruction Description
NOP No operation
4:301