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This HTML version of the file intel.doc from the
PC Game Programmer's guide was produced by Zack T Smith. Fancy HTML modifications are copyright ©
2005 by Zack T Smith, all rights reserved.
This information is provided in the hope that it will be useful,
but without any warranty. It is provided AS-IS,
without even the implied warranty of fitness for a particular purpose.
D Instructions
DAA - Decimal Adjust for Addition
Usage: DAA
Modifies flags: AF CF PF SF ZF (OF undefined)
Corrects result (in AL) of a previous BCD addition operation.
Contents of AL are changed to a pair of packed decimal digits.
Clocks Size
Operands 808x 286 386 486 Bytes
none 4 3 4 2 1
DAS - Decimal Adjust for Subtraction
Usage: DAS
Modifies flags: AF CF PF SF ZF (OF undefined)
Corrects result (in AL) of a previous BCD subtraction operation.
Contents of AL are changed to a pair of packed decimal digits.
Clocks Size
Operands 808x 286 386 486 Bytes
none 4 3 4 2 1
DEC - Decrement
Usage: DEC dest
Modifies flags: AF OF PF SF ZF
Unsigned binary subtraction of one from the destination.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 3 2 2 1 2
mem 15+EA 7 6 3 2-4
reg16/32 3 2 2 1 1
DIV - Divide
Usage: DIV src
Modifies flags: (AF,CF,OF,PF,SF,ZF undefined)
Unsigned binary division of accumulator by source. If the source
divisor is a byte value then AX is divided by "src" and the quotient
is placed in AL and the remainder in AH. If source operand is a word
value, then DX:AX is divided by "src" and the quotient is stored in AX
and the remainder in DX.
Clocks Size
Operands 808x 286 386 486 Bytes
reg8 80-90 14 14 16 2
reg16 144-162 22 22 24 2
reg32 - - 38 40 2
mem8 (86-96)+EA 17 17 16 2-4
mem16 (150-168)+EA 25 25 24 2-4 (W88=158-176+EA)
mem32 - - 41 40 2-4
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