说明：  AT89S51单片机实验及实践教程，通过这本书可以很好的解决，LED、LCD显示，电子钟，电子琴，点阵，数字电压表，ADC0809,DS18B20，电子锁等问题...
(AT89S51 Single-chip experiments and practice course, through this book can be a good solution, LED, LCD display, electronic bell, organ, dot matrix, digital voltage meter, ADC0809, DS18B20, electronic lock and so on ...)