6. A 4-bit ripple counter consists of flip-flops, which each have a propagation delay from clock to Q output of 15 ns. For the counter to recycle from 1111 to 0000, it takes a total of ________.
9. The circuit given below fails to produce data output. The individual flip-flops are checked with a logic probe and pulser, and each checks OK. What could be causing the problem?
Options
A. The data output line may be grounded.
B. One of the clock input lines may be open.
C. One of the interconnect lines between two stages may have a solder bridge to ground.
D. One of the flip-flops may have a solder bridge between its input and Vcc.