# Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 36 (Page No. 258)

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A computer has four page frames. The time of loading, time of last access, and the $R$ and $M$ bits for each page are as shown below (the times are in clock ticks):

1. Which page will NRU replace?
2. Which page will FIFO replace?
3. Which page will LRU replace?
4. Which page will second chance replace?

Ans: (a) Page 1 because R M = 0 0
(b) Page 3 because it is loaded at 110 (First In)
(c) Page 1 because is referenced at 265 (Least Recently)
(d) Page 1 because it is loaded at 120 and the reference bit is 0.

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