说明：  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，与汇编相比，C语言在功能上、结构性、可读性、可维护性上有明显的优势，因而易学易用。
(Keil C51 is the United States Keil Software company produced51 series compatible MCU C language software development system, and compared with the C language compilation, functional, structural, readability, maintainability has obvious advantages, so it is easy to learn and use.)