The contents of a four-bit register are initially 1011. The register is shifted six times to the right, with the serial input being 101101. What are the contents of the register after each shift? (6.4)

First shift - 1101

Second shift - 0110

Third shift - 1011

Fourth shift - 1101

Fifth shift - 0110

Sixth shift - 1011

Explanation:

Each time you shift a register to the right, you do 3 things:

The rightmost digit drops off You move the next three digits over one position to the right You fill in the leftmost position with one of the numbers from your serial input.

Contents are initially 1011. The 1 on the right disappears. The leftmost 3 digits (101) end up in the last 3 positions of the register. The first position of the register takes a number from the serial input, which is 1 in this case. So you end up with 1101.

Do this a second time. The rightmost 1 is gone, the 110 end up as the last 3 positions of the register, and you end up with 0 in the leftmost position. This one is 0110.

The remaining 4 follow the same pattern.