说明：  51上运行的实时操作系统,该文档对其进行详细的介绍，还提供了许多例子！对于想在51上实现简单的多任务系统，不需要自己嵌入，因为keil工具中已经有了内核
(51 running real-time operating systems, the documentation for its detailed descriptions, it also provided many examples! For the 51 to achieve a simple multi-tasking system, not embedded themselves, because Keil tools have kernel)