简单延时程序、子程序调用、带参数子程序设计、流水灯同时蜂鸣器响、如何驱动蜂鸣器，及如何驱动继电器，集电极开路的概念及应用。-A simple delay procedure, subroutine calls, subroutine parameters design, water lamps at the same time buzzer ring, how to drive buzzer, and how to drive relays, open collector concepts and applications.