1. iterator

2. does a "yield hold"; hardware timer goes off; thread does a keyboard
read or other system call

3. 30, 36, 66

4.

def main():
   initialize()
   MaxSimtime = 10000
   for I in range(2):
      M = MachineClass()
      activate(M,M.Run())
   MaxSimTime = 10000.0
   simulate(until=MaxSimtime)
   # added
   tmp = (2*MaxSimTime - MachineClass.TotalUpTime) / MachineClass.NRep
   print tmp