数字钟电路系统由主体电路和扩展电路两大部分组成。其中，主体电路完成数字钟的基本功能，扩展电路完成数字钟的扩展功能。用MAXPLUSⅡ进行电路设计与仿真.-digital clock circuit system from the main circuit and the circuit extended two major components. Among them, the main circuit digital clock to