模拟器有三个过程：主，M0、M1、所有的运行

代码说明：

The simulator has three processes: main, M0, and M1, all of which run * independently. Set them all up first. Once set up, main maintains the * clock (tick), and picks a process to run. Then it writes a 32-bit word * to that process to tell it to run. The process sends back an answer * when it is done. Main then picks another process, and the cycle repeats. */-The simulator has three processes: main, M0, and M1, all of which run * independently. Set them all up first. Once set up, main maintains the * clock (tick), and picks a process to run. Then it writes a 32-bit word * to that process to tell it to run. The process sends back an answer * when it is done. Main then picks another process, and the cycle repeats. */