User's Manual

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.
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