A register is referred to as a universal shift register if it can be operates in all the four possible modes and also as a bi directional register.

In following is of 4 bit universal shift register, this circuit can be used in any of following modes as,

1] Serial in, serial out (SI SO)

2] Serial in, parallel out (SI PO)

3] Parallel in, serial out (PI SO)

4] Parallel in, parallel out (PI PO)