synchronus reset with simple respected clock.it is required more no of gates,and it is didnt have metastabilty problem.it is working is slow. ) x4 O# h2 J6 k# ^2 R 6 N2 n4 ]4 a' yasynchronous reset with out respected to the clock.it is required less no .of gates.it is suffer to the metastability problem.it is working is fast