说明：  AT89S51 单片机实验及实践系统板使用说明书,内有原理图,程序例子.（集成多个硬件资源模块，每个模块各自可以成为独立的单元，也可以相互组合，因此，可以为不同阶层的单片机爱好者及单片机开发者提供不同的开发环境。
(AT89S51 Single-chip experiments and practice of system board manual, with schematics, procedures examples. (Integrated a number of hardware resources modules, each module can be independent of their respective units, each combination can be, therefore, can be different levels Single-chip Single-chip enthusiasts and developers to provide different development environment.)