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THE
80286
INSTRUCTION SET
MUL-Unsigned
Multiplication of
AL
or
AX
Opcode
F6
/4
F7
/4
FLAGS MODIFIED
Overflow, carry
Instruction
MUL eb
MUL
ew
FLAGS UNDEFINED
Sign, zero, auxiliary carry, parity
OPERATION
Clocks
13,mem=16
21,mem=24
Description
Unsigned multiply
(AX
=
AL
X
EA
byte)
Unsigned
multiply
(DXAX
=
AX
X
EA
word)
If
MUL
has a byte operand, then the byte
is
multiplied
by
AL, and the result
is
left
in
AX. Carry and
overflow are set to
0 if AH
is
0;
they are set to 1 otherwise.
If
MUL
has a word operand, then the word
is
multiplied
by
AX, and the result
is
left
in
DX:AX. DX
contains the high order
16
bits of the product. Carry and overflow are set to 0 if DX
is
0;
they are set
to 1 otherwise.
PROTECTED MODE EXCEPTIONS
#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.
8-76