0关闭外部中断定时器0中断用做显示timer0i
terrupt1定时器0中断是1号TH00xfd写入定时器0初始值TL00x77switchflagcase0x00P0geP20x7fflagbreakcase0x01P0shiP20xbfflagbreakcase0x02P0baiP20xdfflag0break
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