This input port is to the first flip-flop in the register. Since we have a serial input, we will take only one input port. And all of them have the same reset input. Okay, so we know that we have four D flip-flops. How to design a 4-bit Serial In Serial Out shift register (SISO)?

To convert between serial-parallel – Since we have both serial and parallel types of inputs and outputs, we can use shift registers to convert serial data to parallel or vice versa.

So we can use them to introduce some delay if we need it. Either way, the processes consume some clock cycles.

To produce a delay – The data can stay inside the shift register or pass through it.

In the absence of a clock pulse, the shift register holds that data.

To store data – The flip-flops shift data on the application of a clock pulse.

In this post, we will look at shift registers where the data moves in the right direction.

To shift data – Shift registers can shift data either to the right, to the left or in both directions.

The types of inputs and outputs of these four categories are evident from their names. Doing that, we get four main configurations. We can classify shift registers depending on these two data flow methods. So we have two ways in which data can ‘flow’ through a shift register. Similarly, each flip-flop can have its own output too.

This particular setting of giving input is known as parallel input. Parallel: Each flip-flop can have its own input.The output is in the same order as the input. We get the data output at the last flip-flop. Each bit passes through the cascade in a line. Serially: Data enters the cascade of flip-flops in a stream.We can feed and extract data to and from a shift register in two ways:

Commonly available Shift Register ICs (source) How do shift registers move data?.Some commonly available shift registers.

How to design a 4-bit Parallel in Serial Out shift register (PISO)?.How to design a 4-bit Parallel in Parallel Out shift register (PIPO)?.How to design a 4-bit Serial In Parallel Out shift register (SIPO)?.How to design a 4-bit Serial In Serial Out shift register (SISO)?.

Parallel to serial converter timing