12. (8 pts) A 4-bit shift register and serial data input waveform are shown as follows. The output is Q = QQ2QIQ.. Draw the waveforms, Qo. QLQ2 Q3 for the first six clock cycles. Write down the value of Q = Q:QQiQo at the fourth clock cycle and the sixth clock cycle. (The clock is counted from 1.) 0 10, ax UUUUUUU Data Input