Make a table showing which of the processes P1, P2, and P3 are running and which are blocked as a function of time from 0 to 1000 msec. All three processes perform up and down instructions on the same semaphore. When two processes are blocked and an up is done, the process with the lower number is restarted, that is, P1 gets preference over P2 and P3, and so on. Initially, all three are running and the semaphore is 1.
 At t = 100 P1 does a down
 At t = 200 P1 does a down
 At t = 300 P2 does an up
 At t = 400 P3 does a down
 At t = 500 P1 does a down
 At t = 600 P2 does an up
 At t = 700 P2 does a down
At t = 800 P1 does an u
p At t = 900 P1 does an up
