19. Operating System a) Describe THREE events that could cause a process in running state transiting to a different state. (3 marks) b) Consider a UNIX file system with 10 direct pointers, 1 single-indirect pointer, and 1 double-indirect pointer in the i-node. Assume that the size of each disk block is 8KB and each pointer to a disk block requires 4 bytes. What is the largest possible file that can be supported with this design? Show the expression (3 marks) c) A disadvantage of both Interrupt driven 1/0 and Programmed I/O is that data must travel over the system bus twice: first to the CPU and then again to its destination. Name one 1/0 technique which does NOT need this to happen AND explain why. (3 marks) d) Suppose there are four processes in the ready queue: P1, P2, P3, and P4. For each process, the CPU burst time and priority are given below. Suppose lower numbers represent high priority and there is no VO operation involved in these processes Show how these four processes are dispatched using a Priority Scheduling algorithm. AND identify one key problem with this scheduling algorithm. Process Burst Time Priority 15 2 2. 7 1 3 2 4 10 3 (6 marks) e) Suppose that there are 3 free page frames (1, 2, 3) and 5 virtual pages named as A, B, C, D. E. Given the page reference stream as: AB CADABEBA Show the page replacement sequence using the LRU Page Replacement algorithm