AAD: ASCII Adjust for Division though the names of these 2 instructions (AAM and AAD) seem to be same, there is many difference between their functions. The AAD instruction converts 2 unpacked BCD digits in AL and AH to the corresponding binary number in AL. This adjustment might be made before dividing the 2 unpacked BCD digits in the AX by an unpacked BCD byte. SF, PF, ZF are modified whereas CF, AF, OF are not defined, after the execution of the instruction AAD. The instance describes the execution of the instruction. This instruction seems before DIV instruction unlike the AAM seems after MUL in the instruction sequence. Assume AX has 0508 unpacked BCD for 58 decimal, and DH consist 02H.Example :
The conclusion of the AAD execution will give the hexadecimal number 3A in the AL and 00 in the AH. Notice that 3A is the hexadecimal correspondent of 58 (decimal). Now, the instruction DIV DH can be executed. So rather than ASCII adjust for division, it is ASCII adjust before division operation. All the ASCII adjust instructions are also known as unpacked BCD arithmetic instructions. Now, we will consider the two instructions related to the packed BCD arithmetic.