最简单的分页替换算法就是先进先出算法，当每次有新的分页需要调入时，会选择调入内存时间最久的分页换出。有两种实现的方法：第一种是记录每个分页被调入到页框的时间，当每次需要换出分页时，会找到调入时间最早的一页，也就是在主存储器中存在最久的分页。另外一种方式就是利用FIFO队列来实现，当要进行分页替换时，就把队列最前端的分页换出，再把要调入的分页放到队列的末端。(The simplest paging replacement algorithm is the first in first out algorithm. Each time a new page needs to be transferred in, it will select the page swapping out with the longest time in memory. There are two ways to achieve this: the first is to record the time when each page is called into the page box. When each page needs to be changed out, the earliest page will be found, that is, the longest page in main memory. Another way is to use FIFO queue to achieve, when the page replacement, the front-end of the queue page out, and then put the page to be transferred to the end of the queue.)