5.1 Introduction ◆Review *Combinational Circuits（组合电路) No Storage,No Feedback. The output level is at all times dependent on the combination of input levels. *Sequential Circuits(时序电路) Storage involved,Feedback involved The output depends not only on the present value of inputs,but also on past inputs. • No Storage, No Feedback. • The output level is at all times dependent on the combination of input levels. •Storage involved, Feedback involved •The output depends not only on the present value of inputs, but also on past inputs. 5.1 Introduction ◆Review Combinational Circuits （组合电路）  Sequential Circuits （时序电路）