When the Count signal goes from 1 to 0, flip flop A is triggered. If it started out at 0, it goes to 1. The 0 to 1 transition on the output of A, and thus on the clock input of B, has no effect. When the next negative transition on Count occurs, A will go from 1 to 0 causing the clock input to B to do the same. Since J and K are 1, flip flop B will change states. Since there is a delay from the clock edge to the output change, flip flop B is clocked somewhat later than A and thus its output changes later. This is emphasized in the timing diagram of Figure 7.9. We assume in this diagram that flip flops A and B both start at 0.