汇编把AL最低位送到BL最低位，但保持AL不变

.model small.code.startup      mov al,03h      mov bl,08h      ror bl,1      ror al,1      rcl bl,1      rol al,1      cmp al, 03h      jz nextnext1:mov ah,02h      mov dl,'N'      jmp zhongzhi    next: cmp bl,09h      jz shutdown      jmp next1      shutdown: mov ah,02h          mov dl,'Y'zhongzhi: int 21h.exit 0end