入通过键盘控制或者通过50MHz晶振分频后以每1秒步长发生变化，通过8位并口输出数字信号，并将该数字信号经过译码电路后用七段数码管提示输出信息。-By controlling the keyboard or by 50MHz crystal occur long after the division to change every second step, through the 8-bit parallel digital output signal, and the digital sign