Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

Vol. 2 3-7
INSTRUCTION SET REFERENCE, A-M
3.1.1.3 64-bit Mode Column in the Instruction Summary Table
The “64-bit Mode” column indicates whether the opcode sequence is supported in
64-bit mode. The column uses the following notation:
• Valid — Supported.
• Invalid — Not supported.
• N.E. — Indicates an instruction syntax is not encodable in 64-bit mode (it may
represent part of a sequence of valid instructions in other modes).
• N.P. — Indicates the REX prefix does not affect the legacy instruction in 64-bit
mode.
• N.I. — Indicates the opcode is treated as a new instruction in 64-bit mode.
• N.S. — Indicates an instruction syntax that requires an address override prefix in
64-bit mode and is not supported. Using an address override prefix in 64-bit
mode may result in model-specific execution behavior.
3.1.1.4 Compatibility/Legacy Mode Column in the Instruction Summary
Table
The “Compatibility/Legacy Mode” column provides information on the opcode
sequence in either the compatibility mode or other IA-32 modes. The column uses
the following notation:
• Valid — Supported.
• Invalid — Not supported.
• N.E. — Indicates an Intel 64 instruction mnemonics/syntax that is not
encodable; the opcode sequence is not applicable as an individual instruction in
compatibility mode or IA-32 mode. The opcode may represent a valid sequence
of legacy IA-32 instructions.
3.1.1.5 Description Column in the Instruction Summary Table
The “Description” column briefly explains forms of the instruction.
3.1.1.6 Description Section
Each instruction is then described by number of information sections. The “Descrip-
tion” section describes the purpose of the instructions and required operands in more
detail.