SHIFT REGISTER
Data storage and data movement are the two basic functions of a register it is a digital circuit consists of one or more flip flops which are used to store and shift the data this device loads the data in its inputs and then shifts it to the output during every clock cycle and hence its name is shift register. The storage capacity of a register is the total number of the register which is the total number of digital data that it can retain The shifting of binary data from one stage to other or into or out of the register according to the clock pulse then it is known as a shift register. A shift register consists of several D type data latches some of the data latches are for a logic “0” and others are for a logic “1” and it is connected in a serial chain so the output from one latch can become the input of another one.
This is the simple form of a register which has four D flip-flops the input is given to the D and the output are taken at the Q of the flip-flop
The IC’s of the shift register is provided with the clear or reset connection so that it could be SET and RESET as needed Shift registers can be operated in four different modes they are SIPO, SISO, PIPO, PISO
SIPO
serial-in to parallel-out – in this type the register is loaded with serial data, one bit at a time, and the stored data will be available at the output in parallel form
SISO Serial-in to serial-out – in this type the data is shifted serially in and out of the register either in the left or right direction which will be under the clock control
PISO parallel-in to serial-out – in this type the data will be loaded to the register and then the parallel data which is loaded will be shifted out of the register serially one bit at a time and it will be under clock control
PIPO
In this type parallel data is loaded into the register and it will be transferred together with the same clock pulse to the respective outputs
APPLICATIONS OF SHIFT REGISTERS • The complexity of the connection between two devices can be reduced • It can be used for time delays • They are used in state registers • It can be used for parallel to serial or serial to parallel conversions • It could be used as a sequence generator • It is also used as a counter • It is used in calculators and computer for the storage of data