The state diagram below represents one of the many possible 2?bit state machines that can be used to perform prediction. Explain, in plain English, what it does.

1. If you are in state S1 (not taken) and the next branch is taken, you go straight to state S3, the strongly taken

state.

2. If you are in state S3, a taken branch takes you to state S2 (rather than back to state S3). State S3 is not a

saturating state. If there is a sequence of taken branches, the system oscillates between S2 and S3. From

state S3 the next state is always state S2 (since a taken and a not taken have the same destination).

We can regard S0 as a strongly not taken state and all not taken branches lead towards this state. States S0, S1,
S2, S3 behave exactly like the corresponding states in a saturating counter with respect to not taken branches.
The differences between this and a saturating counter are: