A bidirectional 4-bit shift register is storing the nibble 1101. Its  input is HIGH. The nibble 1011 is waiting to be entered on the serial data-input line. After three clock pulses, the shift register is storing ________.

ANS:B - 0111

signal line high means shift right

shift | waiting nibble | stored nibble
--------------------|------------------|------------------
initially | 1011: | 1101
right shift (1) | 101 | 1:110
right shift (2) | 10 | 11:11
right shift (3) | 1 | 011:1


rule : when a stored nibble bit is shifted out, a waiting nibble bit is shifted inn
Hence after the 3rd shift, the stored nibble is 0111

nice!!! (