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PEAC seen as a collection of 2-tap LFSRs

A project log for PEAC Pisano with End-Around Carry algorithm

Add X to Y and Y to X, says the song. And carry on.

Yann Guidon / YGDESYann Guidon / YGDES 08/07/2021 at 21:410 Comments

From the beginning, the link between LFSRs and PEAC was clear, if only the right perspective was used.

So I made an emulation with CircuitJS to make it obvious:

The w4 configuration has a pair of orbits with 135 steps, which don't fit in the screen.

Each level is made of 2 DFF and one full-adder, just like a 2-tap Fibonacci LFSR with a more complex feedback circuit:

One possible application is as a serial-line scrambling circuit (think Ethernet, USB and other asynchronous links), since it can't "get stuck" like a LFSR.

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