- SISO Shift Register Definition: A Serial In Serial Out (SISO) shift register is defined as a type of shift register where data is loaded and retrieved in serial mode.
- Right-Shift Operation: In a right-shift SISO shift register, data bits move towards the right with each clock pulse.
- Left-Shift Operation: A left-shift SISO shift register works similarly but moves data bits from right to left.
- Working Principle: The working principle of SISO shift registers involves data entering bit-by-bit and moving through flip-flops with each clock pulse.
- Initial Setup: All flip-flops are cleared initially, and input data is fed serially to the first flip-flop.
Serial In Serial Out (SISO) shift registers load bits one at a time and read them from the shift register the same way. Figure 1 is an n-bit rising-edge SISO shift register. The word enters the first flip-flop one bit per clock. Every later stage except FF1 is driven by the stage before it: FF2 takes the output of FF1. The stored word leaves at the nth flip-flop, still one bit per clock.
Clear every flip-flop first by driving the clear pins high. Then feed the word serially into FF1.
The bit on D1 (B1) is stored in FF1 on the first rising clock. On the second clock B1 moves into FF2 and a new bit enters FF1 (B2).
Each later rising clock moves every bit one stage to the right. Figure 1 is therefore a right-shift SISO shift register. The first input bit reaches the nth flip-flop on the nth clock. Later clocks send the rest of the word out in the same order (Table I). Figure 2 is the matching waveform.
A left-shift SISO shift register (Figure 3) uses the same serial load and serial read. The bits move the other way, right to left.
