说明：  非常完善的小型操作系统代码!是学习操作系统的最好的一个，代码最少，但操作系统的内容全部包括在内！上学时候学习用的！
(Very well-established small-scale operating system code! Is learning one of the best operating system, code at least, but the content of operating systems include all! When used to go to school to learn!)