Flip-flop shift register

There are mainly three types of flip-flop shift registers. They are D flip-flop shift register, JK flip-flop shift register and RS flip-flop shift register. D flip-flop shift register consists of a 4-bit shift register using D-type flip-flops. Serial data is fed at the D-input of the flip-flop. This type of register is also called as serial-in parallel-out shift register. Positive edge triggered flip-flops are used here. In JK flip-flop shift register, normal and complement outputs of each flip-flop are connected to J and K inputs of the subsequent flip-flop. The reset inputs of all the flip-flops are connected to a common reset input through an inverter. Negative edge triggered flip-flops are used here. JK flip-flop shift register is a synchronous circuit. IC 7491 is an 8-bit RS flip-flop shift register where RS flip-flops are used.