数字式秒表设计(设计一个数字式秒表，一个最简单的数字秒表由毫秒信号发生电路，分、秒、毫秒计数电路，译码显示电路组成。)

Digital stopwatch design (design a digital stopwatch, a simplest digital stopwatch consists of a millisecond signal generation circuit, minute, second, millisecond counting circuit, decoding display circuit.)