3-459
INSTRUCTION SET REFERENCE
ORLogical Inclusive OR
Description
This instruction performs a bitwise inclusive OR operation between the destination (first) and
source (second) operands and stores the result in the destination operand location. The source
operand can be an immediate, a register, or a memory location; the destination operand can be
a register or a memory location. (However, two memory operands cannot be used in one instruc-
tion.) Each bit of the result of the OR instruction is 0 if both corresponding bits of the operands
are 0; otherwise, each bit is 1.
Operation
DEST
<
DEST OR SRC;
Flags Affected
The OF and CF flags are cleared; the SF, ZF, and PF flags are set according to the result. The
state of the AF flag is undefined.
Opcode
Instruction
Description
0C ib
OR AL,imm8
AL OR imm8
0D iw
OR AX,imm16
AX OR imm16
0D id
OR EAX,imm32
EAX OR imm32
80 /1 ib
OR r/m8,imm8
r/m8 OR imm8
81 /1 iw
OR r/m16,imm16
r/m16 OR imm16
81 /1 id
OR r/m32,imm32
r/m32 OR imm32
83 /1 ib
OR r/m16,imm8
r/m16 OR imm8 (sign-extended)
83 /1 ib
OR r/m32,imm8
r/m32 OR imm8 (sign-extended)
08 /r
OR r/m8,r8
r/m8 OR r8
09 /r
OR r/m16,r16
r/m16 OR r16
09 /r
OR r/m32,r32
r/m32 OR r32
0A /r
OR r8,r/m8
r8 OR r/m8
0B /r
OR r16,r/m16
r16 OR r/m16
0B /r
OR r32,r/m32
r32 OR r/m32
