Published by: Dikshya
Published date: 13 Jul 2023
Shift registers are sequential logic circuits that store and transfer data in a series of bits. They consist of a chain of flip-flops connected in series, with the output of one flip-flop connected to the input of the next. The data can be shifted (moved) through the register, allowing for various data storage and manipulation operations.
Some key points about shift registors:
Serial Data Transfer: Shift registers enable serial data transfer, where data is transmitted or received one bit at a time. The bits can be shifted in (input) or shifted out (output) of the register.
Clock Signal: Shift registers typically use a clock signal to control the shifting of data. The clock signal synchronizes the shifting operation and determines the speed at which data moves through the register.
Data Input: Shift registers can have serial or parallel data inputs. Serial-in shift registers receive data one bit at a time through a single input line. Parallel-in shift registers receive multiple bits simultaneously through parallel input lines.
Data Output: Shift registers can have serial or parallel data outputs. Serial-out shift registers output data one bit at a time through a single output line. Parallel-out shift registers output multiple bits simultaneously through parallel output lines.
Shift Directions: Shift registers can shift data in two directions: right-shift or left-shift. In a right-shift operation, data moves from the leftmost flip-flop to the rightmost flip-flop. In a left-shift operation, data moves in the opposite direction, from the rightmost flip-flop to the leftmost flip-flop.
Applications: Shift registers have various applications, including:
Shift registers come in different configurations, such as the basic shift register, ring counter, Johnson counter, and universal shift register. These configurations provide different functionalities and can be tailored to specific application requirements. Overall, shift registers play a crucial role in digital systems for data manipulation, storage, and transfer operations, providing flexibility and versatility in handling data in a sequential manner.
The four common types of shift registers:
Serial-in, Serial-out (SISO): In a SISO shift register, data is entered serially (one bit at a time) and shifted out in the same serial fashion. It has one input line (serial input) and one output line (serial output). The bits are shifted through the register, and each new bit entered replaces the previous bit. This type of shift register is useful for applications where data needs to be shifted through a single line or transmitted serially.
Serial-in, Parallel-out (SIPO): In a SIPO shift register, data is entered serially but is outputted in parallel. It has one input line (serial input) and multiple output lines (parallel output). The serially inputted bits are shifted through the register, and when all the bits are loaded, they can be outputted simultaneously in parallel. This type of shift register is commonly used for tasks like data storage and parallel-to-serial conversion.
Parallel-in, Parallel-out (PIPO): In a PIPO shift register, data is entered and outputted in parallel. It has multiple input lines (parallel input) and multiple output lines (parallel output). The bits are loaded simultaneously into the register and can be outputted in the same parallel format. PIPO shift registers are often employed in applications where data needs to be stored temporarily or transferred in parallel.
Parallel-in, Serial-out (PISO): In a PISO shift register, data is entered in parallel but is outputted serially. It has multiple input lines (parallel input) and one output line (serial output). The parallel input bits are loaded into the register simultaneously and then shifted out serially, one bit at a time. PISO shift registers are used for tasks like parallel-to-serial conversion and data transfer through a single line.