Serial In – Serial Out || Registers and Counters || Bcis Notes

Serial In – Serial Out

SISO – Definition

A shift register is a digital memory circuit found in calculators, computers and data-processing systems. Bits enter the shift register from one end and emerge from another end. It is used in converters that translate parallel data into serial and vice versa.

SISO shift registers are shift registers that stream in data serially (One bit per clock cycle) and stream out data too in the same way, one after the other.

The SISO shift register is one of the simplest of the four configurations as it has only three connections, the SI which determines what enters the left-hand flip-flop, the serial output (SO) which is taken from the output of the right-hand flip-flop and the sequencing clock signal (Clk).

SISO Shift Register (Shift Right Mode)

 

Output Waveform of SISO shift register

 

Working Mechanism of SISO 4-bit shift register

• Here, the data is allowed to flow straight through the register and out of the other end.
• Since there is only one output, the data leaves the shift register one bit at a time in a serial pattern, hence the name.
• It has three connections, the SI, which determines what enters the left-hand flip-flop, the SO which is taken from the output of the right-hand flip-flop and the sequencing clock signal(Clk).

Q. What’s the use of SISO shift register if output data is exactly the same as the input data?

• Acts as temporary storage devices.
• Acts as a time delay device for the data, with the amount of time delay controlled by the no. of registers 4, 8, 16, etc varying with the clock pulse.

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