Several subsets of the general sequential circuit model ExcitationⅤ ariables INPUT(t)- Combinational Combinational Memory Transform M (S) (g) OUTPUT(O) State Variables E=f Excitation variables S,+1=f(S,E INPUT(t)→ Combin Combinational O=gs Memory Transform M (S) OUTPUT(O) State variables sequential delay modelSeveral Subsets of the general sequential circuit model Excitation Variables Memory M State Variables CLK (E) Combinational Transform (f) INPUT(t) （S） Combinational Logic （g） OUTPUT(O) Excitation Variables Memory M State Variables CLK (E) Combinational Transform (f) INPUT(t) （S） Combinational Logic （g） OUTPUT(O) sequential delay model E=f(I) St+1=f(St ,E) O=g(St )