User's Manual

THE 80286 INSTRUCTION SET
OR - Logical Inclusive OR
Opcode Instruction Clocks
08
Ir
OR eb,rb 2,mem=7
09
Ir
OR eW,rw 2,mem=7
OA
Ir
OR rb,eb 2,mem=7
08
Ir
OR rw,ew 2,mem=7
OC
db OR AL,db
3
00 dw OR AX,dw 3
80
11
db
OR eb,db 3,mem=7
81
11
dw OR eW,dw 3,mem=7
FLAGS MODIFIED
Overflow=O, sign, zero, parity, carry=O
FLAGS UNDEFINED
Auxiliary carry
OPERATION
Description
Logical-OR byte register into EA byte
Logical-OR word register into EA word
Logical-OR EA byte into byte register
Logical-OR EA word into word register
Logical-OR immediate byte into AL
Logical-OR immediate word into AX
Logical-OR immediate byte into EA byte
Logical-OR immediate word into
EA word
This instruction computes the inclusive OR of the two operands. Each bit of the result is 0 if both
corresponding bits of the operands are
0; each bit is 1 otherwise. The result is placed in the first
operand.
PROTECTED MODE EXCEPTIONS
#GP(O) if the result is in a non-writable segment. #GP(O) for an illegal memory operand effective
address in the CS, DS,
or ES segments; #SS(O) for an illegal address in the SS segment.
REAL ADDRESS MODE EXCEPTIONS
Interrupt 13 for a word operand at offset OFFFFH.
8-80