FIFO page replacement
This is the easiest page replacement algorithm. Here the 1st page toward the inside is the 1st to leave that is the oldest page leaves. To execute this we use a queue and the page at the head of the queue is the one being removed. The new page is put-in at the tail of the queue. The drawback is that its performance is not always good.
Example Consider a three frame memory and if the sequence in which pages come into the memory is 1, 2,3,4,1 then 1, 2, 3 are entered into the memory in-order. When the page 4 is required after that 1 is removed and the new page 4 is inserted at the tail end with the head being 2. Now if 1 comes after that 2 is removed as it is the new head.