;计算非压缩型BCD码(ASCII)的加法运算：sum<--962+853,
;并将结果1815显示在屏幕上。
data segment
a1 db '9','6','2'
                          ;a1 db '2','6','9'         
a2 db '8','5','3'         
                          ;a2 db '3','5','8'     
sum db 4 dup(?)
data ends
code segment
assume cs:code,ds:data
begin: mov ax,data
       mov ds,ax
       mov es,ax
       mov si,offset a1      
       add si,2           ;+
       mov bx,offset a2      
       add bx,2           ;+
       mov di,offset sum
       mov cx,3
       mov ah,0
l1:    std
                          ;cld
       lodsb 
       sahf
       adc al,[bx]
       aaa
       lahf
       or al,30h
       cld                ;+
       stosb
       dec bx
                          ;inc bx
       loop l1
       and ah,01h
       or ah,30h
       mov [di],ah
       mov ah,2
       mov cx,4
l2:    mov dl,[di]
       int 21h
       dec di
       loop l2
       mov ah,4ch
       int 21h
code   ends
       end begin