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Abbreviations and legends

        286+            Instruction executes only on an 80286 CPU
                        or later. Requires a p286 or p286n directive
                        to assemble. Appears as 'CPU: 286+' in text
                        entry.

        P or p          Instruction is normally used only in
                        system software (protected mode).
        P               Instruction is privileged in protected
                        mode, including V86 mode. Appears as 'Priv'
                        in text entry.
        r               Use of instruction is restricted.

        IO              Instruction is IOPL-sensitive in protected
                        mode, including V86 mode (CLI and STI only).
        IOpm            Instruction is IOPL-sensitive in protected
                        mode (except in V86 mode).
        IOv86           Instruction is IOPL-sensitive in virtual
                        8086 mode (V86) only.

        eBX             BX or EBX, depending on operand-size attribute
                        or address-size attribute.


        acc             AL, AX or EAX unless specified otherwise
        reg             any general register
        r8              any 8-bit register
        r16             any general purpose 16-bit register
        r32             any general purpose 32-bit register
        r/m8            a one-byte operand that is either a byte
                        register or a byte from memory
        r/m16           a word register or memory operand used for
                        instructions whose operand-size attribute is 16 bits
        r/m32           a doubleword register or memory operand used for
                        instructions whose operand-size attribute is 32 bits
        imm             immediate data
        imm8            immediate signed 8-bit value
        imm16           immediate signed 16-bit value
        imm32           immediate signed 32-bit value
        mem             memory address
        mem8            address of 8-bit data item
        mem16           address of 16-bit data item
        mem32           address of 32-bit data item
        mem48           address of 48-bit data item
        rel8            a relative address (distance -128 to +127 bytes)


        Flags           *  Changed to reflect the results of
                           instruction
                        0  Always cleared
                        1  Always set
                        -  Unchanged
                        ?  Undefined after operation (flag may or may
                           not have changed)

        BCD             Binary-Coded Decimal
        CPL             Current Privilege Level (protected mode)
        IOPL            Input/Output Privilege Level (protected mode)
        SMM             System Management Mode



        Instruction timings
        n       generally refers to a number of repeated counts
        m       in a jump or call,
                286:     bytes in next instruction
                386/486: number of components in instruction
                         (each byte of opcode) + 1 (if immediate data)
                         + 1 (if displacement)

        EA      cycles to calculate the Effective Address
                8088/8086:
                  base = 5,  index = 5,  disp = 6
                  bp+di or bx+si = 7
                  bx+di or bp+si = 8
                  bp+di+disp or bx+si+disp = 11
                  bx+di+disp or bp+si+disp = 12
                  segment override = +2
                286 - 486:
                  base+index+disp = +1    all others, no penalty

        NP      not pairable                      } pairing
        UV      pairable in the U pipe or V pipe  } categories
        PU      pairable in the U pipe only       } for
        PV      pairable in the V pipe only       } Pentium



        Instruction length
        The byte count includes the opcode length and length of any required
        displacement or immediate data. If the displacement is optional, it
        is shown as d() with the possible lengths in parentheses. If the
        immediate data is optional, it is shown as i() with the possible
        lengths in parentheses.