This Shift Register is a cascade of 1 Wide D Flip-Flops, sharing the same clock, nwhich has the output of any one but the last flip-flop connected to the "data" ninput of the next one in the chain, resulting in a circuit that shifts by one nposition, when enabled to do so by a transition of the clock input. Much like ncounters, they are a form of Sequential logic, unlike combinational logic is not nonly affected by the present inputs, but also, by the prior history. In other nwords, sequential logic remembers past events.

Registers in a CPU have a nfixed width, so some bits will be "shifted out" of the register at one end, nwhile the same number of bits are "shifted in" from the other end; the ndifferences between bit shift operators lie in how they determine the values of nthe shifted-in bits.

Logical Shift Right or Left:

In a logical nshift, the bits that are shifted out are discarded, and zeros are shifted in (on neither end). This inserts bits with value 0 instead of copying in the sign bit. nHence the logical shift is suitable for unsigned binary numbers,

Rotate nShift:

Another form of shift is the circular shift or bit rotation. In nthis operation, the bits are "rotated" as if the left and right ends of the nregister were joined. The value that is shifted in on the right during a nleft-shift is whatever value was shifted out on the left, and vice versa. This noperation is useful if it is necessary to retain all the existing bits, and is nfrequently used in digital cryptography.

It is also possible to make nShift Registers using JK Flip Flips, but in comparisson, a D Flip Flop is ALOT nsmaller in size, so i would'nt bother. Unless you feel like Challenging nyourself. Have Fun

roboticaust:
http://www.youtube.com/roboticaust

Bitwise nOperation:
http://en.wikipedia.org/wiki/Bitwise_operation

Shift nRegister:
http://en.wikipedia.org/wiki/Shift_register