内含四个关于单片机的设计，一个交通灯，一个电子密码锁，一个节拍器，一个多首音乐播放器，都附有源程序和电路图，每个都是用c和汇编两种编译软件分别实现-Includes four on the SCM design, a traffic light, an electronic code lock, a metronome, more than one in the first music player, all with source c