Keil C51 是美国Keil software 公司出品的51系列兼容单片机C语言软件开发系统。Keil C51软件提供了丰富的库数据和功能强大的集成开发调试工具μVision2全是windows界面。只要看一下编译后生成的汇编代码，就能体会到keil C51生成的目标代码的效率之高，多数语句生成的汇编代码很紧凑，容易理解。在开发大型软件时更能体现高级语言的优势。Keil的版本目前是V7版本，他是很优秀的8051C编译器。(Keil C51 is the 51 series compatible MCU C language software development system produced by Keil software company in the United States. Keil C51 software provides a wealth of library data and powerful integrated development and debugging tools - Vision2 is all windows interface. As long as we see compiled compiled code, we can see that the target code generated by keil C51 is highly efficient. Most of the assembly codes generated by most sentences are compact and easy to understand. In developing large software, the advantage of advanced language is more embody. The version of Keil is currently the V7 version, and he is an excellent 8051C compiler.)