AAD              ASCII Adjust before Division        Flags: O D I T S Z A P C
?       * * ? * ?

Logic:    AL   AH * 10 + AL
AH   0

AAD converts the unpacked two-digit BCD number in AX into binary in
preparation for a division using DIV or IDIV, which require binary
rather than BCD numbers.

Operands                  Clocks   Transfers  Bytes   Example
no operands                 60         -        2     AAD

AAD modifies the numerator in AL so that the result produced by a
division will be a valid unpacked BCD number. For the subsequent DIV
to produce the correct result, AH must be 0. After the division, the
quotient is returned in AL, and the remainder in AH. Both high-order
nibbles are zeroed.

Note:          Unpacked BCD stores one digit per byte; AH contains
the most-significant digit and AL the least-
significant digit.

See also: AAA
See also: AAS
See also: AAM
See also: DIV
See also: IDIV
See also: Flags

AAD ASCII Adjust before Division