b) What are messages? What are the operating system primitives to manipulate messages? Can messages be used to enforce mutual exclusion? Explain your answer [10 Marks] c) In the context of a virtual memory page replacement policy, describe the workings of the "clock" based algorithm. Show what the status of the buffer, presented in Figure 1 below will be after a cycle of the "clock replacement" algorithm has taken place. Notes: . You should draw the full updated status buffer * You can assume the incoming page number is 234 . You should list each of the steps that led to the new buffer status First frame in circular buffer of frames that are candidates for replacement page 9 page 19 page 1 use 1 45 2 next frame page pointer page 191 use = 1 age 222 556 page 33 use ! page 67 us-I page 13 use = 0 6