code segment
   assume cs:code
start: mov cl,0
       mov dx,290h
lll:   mov al,cl
	out dx,al
	inc cl        ;cl加1
	inc cl
	inc cl
	inc cl
	inc cl
	inc cl
	inc cl
	push dx
	mov ah,06h      ;判斷是否有鍵按下
	mov dl,0ffh
	int 21h
	pop dx
	jz  lll       ;若無則轉LLL
	mov ah,4ch    ;返回DOS
	int 21h
code ends
   end start