4. Design a 4 bit register with shift right and shift left operations using D flip flops and basic gates. There Is an asynchronous signal named RIGHT/LEFT, If this bit is 1, the operation will be RIGHT shift, otherwise it will be LEFT shift operation. There will be Serial Right Shift Input (SRI) and Serial Right Shift Output (SRO) for Right shift operation. At the same time there will be Serial Left Shift Input (SLI) and Serial Left Shift Output (SLO) for Left shift operation. The block diagram of the circuit is given in Figure 1(right). Figure 1: Excitation table for flip-flops (right) and block diagram for ripple register (right).