在实时嵌入式控制系统中，指令周期对系统的性能有至关重要的影响。介绍几种最常用的微控制器的工作机制，采用一段循环语句对这几种微控制器的指令周期进行测试，并进行分析比较。-In real-time embedded control systems, command cycle on the performance of the system have a critical influence. Introduction of several most commonly used microcontrollers working mechanism, using a section of these different kinds of loop microcontroller instruction cycle test, and analysis and comparison.