58. A Null–Lobur flip-flop (NL flip-flop) behaves as follows: If N = 0, the flip-flop does not change state. If N = 1, the next state of the flip-flop is equal to the value of L.

a) Derive the characteristic table for the NL flip-flop.

b) Show how an SR flip-flop can be converted to an NL flip-flop by adding gate(s) and inverter(s). (Hint: What values must S and R have so that the flip-flop will be set and reset at the proper time when N = 1? How can you prevent the flip-flop from changing state when N =

0?)