说明：  模拟操作系统的进程调度，事先构造一个PCB总链队列，可对该队列进行正常的维护， 即当PCB状态变化时，在总链队列的基础上，实现菜单式管理和进程原语操作， 实现创建、撤销、时间片到、挂起进程和激活进程等基本进程原语， 以实现PCB的就绪队列、等待队列的组织与管理；
(Simulation of the operating system process scheduling, to construct a PCB chain queue, can be used for normal maintenance of the queue, that is when the PCB state changes, based on the total chain queue, to achieve the menu management and process primitives operation, the realization of the creation, revocation, time slice, to hang up process and activation process the basic process of primitives, ready queue and queue waiting for the organization and management to achieve PCB)