code segment
main proc far
   assume cs:code
start:

     mov cl,4
     mov bl,al
     rol bl,cl
     and bl,0fh
     mov dl,ah
     rol dl,ofh
     mov cl,ah
     and cl,ofh
     and al,ofh
     mov ax,4c00h
     int 21h
code ends
main endp
   end start