.model small .586 .stack 100h .data ;opA and opB are two 64 bit numbers in little endian order ;little endian means the least significant byte is stored first opA db 23h,0ABh,34h,80h,39h,01h,0F7h,10h ;10F701398034AB23 h opB db 7Ah,0FFH, 92h, 0D2h, 38h, 81h,0C2h,25h ;25C28138D292FF7A h sum db 8 dup (?) .code main proc mov ax,@data mov ds,ax mov cx,8 mov bx,offset opA mov si,offset sum clc LP1: mov al,[bx] adc al, [bx+8] Mov [si],al Inc bx Inc si Loop lp1 Mov ax, 4c00h Int 21h Main endp End main