用8031单片机实现简易秒表功能并用八段数码管显示。按下启动键，不管原来显示何值，均先从零开始。按下停止键时停止，数字保持不变。显示时间最长为9秒后停止，数字保持为“9”。按下复位键后，数字显示“0”。(A simple stopwatch function is realized with 8031 singlechip and eight segments are used to display it. Press the start key, regardless of the original value, start from zero. Stop when the stop button is pressed, and the number is kept unchanged. The maximum display time is 9 seconds after the stop, the number is kept as "9". After pressing the reset button, the number shows "0".)