e6_4.asm

ZHUYAO ZSHI LAI JIECHUADE LAIDE

data segment
     x1 db 39h
     x2 db 21h
     x3 db 13
     y  db ?
data ends
code segment
     assume cs:code,ds:data
star:mov ax,data
     mov ds,ax
     mov bx,offset x2
     mov cl,[bx]
     add cl,[bx+1]
     mov al,[bx-1]
     sub al,cl
     mov [bx+2],al
     mov ah,4ch
     int 21h
code ends
     end star