Question

The only difference between a combinational circuit and a flip-flop is that _____________

(a) The flip-flop requires previous state

(b) The flip-flop requires next state

(c) The flip-flop requires a clock pulse

(d) The flip-flop depends on the past as well as present states

This question was posed to me during an interview.

Origin of the question is Triggering of Flip Flops in chapter Flip-Flops of Digital Circuits

Answer 1

The correct choice is (c) The flip-flop requires a clock pulse

To explain: Both flip-flop and latches are memory elements with clock/control inputs. They depend on the past as well as present states. Whereas, in case of combinational circuits, they only depend on the present state.