THE
80286
INSTRUCTION SET
IDIV
-Signed
Divide
Opcode
F6
/7
F7
/7
FLAGS MODIFIED
None
Instruction
IDIVeb
IDIVew
FLAGS UNDEFINED
Clocks
17,mem=20
25,mem=28
Overflow, sign, zero, auxiliary carry, parity, carry
OPERATION
Description
Signed divide
AX
byEA
byte
(AL=Quo,
AH=Rem)
Signed divide
DX:AX
by
EA
word (AX=Quo,
DX=Rem)
/
IDlY
performs a signed divide. The dividend
is
implicit; only the divisor
is
given
as
an operand. If the
source operand
is
a BYTE operand, divide AX by the byte. The quotient
is·
stored
in
AL,
and the
remainder
is
stored
in
AH.
If
the source operand
is
a WORD operand, divide DX:AX
by
the word.
The high-order
16
bits of the dividend are in DX. The quotient
is
stored in AX, and the remainder
is
stored in DX. Non-integral quotients are truncated towards
o.
The remainder has the same sign as the
dividend and always has less magnitude than the dividend.
PROTECTED MODE EXCEPTIONS
Interrupt 0 if the quotient
is
too big to fit in the designated register (AL or AX), 'or if the divisor
is
O.
#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
InterJillpt 0 if the quotient
is
too big to fit
in.
the designated register (AL or AX),
orif
the divisor
is
O.
Interrupt
13
for a word operand
at
offset OFFFFH.
8-43
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