.use32
.model tiny
.data
.code
mov ax,@data
mov ds,ax

        in al,021h
        or al,02h
        out 021h,al

        ;ciclo
         mov cx,0ffffh
lab1:    mov bx,0Ffffh
lab2:    dec bx
        jnz lab2
        loop lab1




        in al,021h
        and al,0fdh
        out 021h,al








    mov ax,4c00h
    int 21h
    end