Section 16.5
Review Questions
Multiple bus initiators and arbitration
  1. Why is it not enough for there to simply be a bus busy wire which is used as a kind of traffic light to keep other would-be bus initiators from attempting to use the bus when it is being used by another component?
answer...
because it might happen that two would-be initiators drive that bus busy wire high at exactly the same time and both would get control of the bus and interfere with each other
  1. What do we call the set of rules that govern the behavior of all bus devices to keep them from interfering with each other?
answer...
bus protocol
  1. Besides some buses, where else might decentralized bus contention protocols be used?
answer...
some local area networks such as Ethernet
  1. What do we call the device that imposes centralized bus contention control?
answer...
arbiter
  1. Which wire is used by would-be bus initiators to tell this device that they want to use the bus?
answer...
bus request
  1. Which wire is used to tell a component that it can act as initiator?
answer...
bus grant
  1. Which of the two wires in the previous two questions is really a group of wires, one for each would-be bus initiator?
answer...
bus grant
  1. What do we call one complete use of the bus, from initial request all way to the end of the use?
answer...
bus transaction
  1. Make a totally fair arbiter is hard, one that randomly chooses the next bus initiator. What circuit have we seen so far could act as an arbiter for two devices?
answer...
S-R latch