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3 Input Adder - Printable Version

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3 Input Adder - ASRS_ - 05-06-2020

Hey!

A friend of mine has figured out the logic of how to make a 3 input adder. Here is a diagram of the logic:
[Image: 2020-05-06_23.27.58.png]
So far, me and a group of people have been able to make a fully functional RCA:
[Image: 2020-05-06_23.26.15.png]
And also a fully functional vertical CCA:
[Image: 2020-05-06_23.25.34.png]
The problem is that the vertical CCA is a little slow, and we weren't able to figure out a good way to get it faster.
It uses a little different logic than the diagram since it has some CCA logic included, but theres probably a better way to implement it.
It would be interesting to see what you people would be able to do.


RE: 3 Input Adder - jxu - 06-27-2020

Your "3 input adder" is essentially carry-save addition (one carry-save adder and one standard adder). Functionally a normal adder is already a 3 input adder (rename carry in to input c)

https://people.clarkson.edu/~linh/algorithms/carry%20save%20addition.pdf


RE: 3 Input Adder - Nickster258 - 06-28-2020

Just pasting this here as I found this patent quite interesting. https://patents.google.com/patent/US4783757A/en


RE: 3 Input Adder - Nuuppanaani - 06-28-2020

I built a 3 input PLA adder some years ago using a real life carry design. Can't remember if it's what Nick just linked but might have been. Cool stuff, I can see uses for these in specialized circuits!


RE: 3 Input Adder - jxu - 06-29-2020

(06-28-2020, 02:30 AM)Nickster258 Wrote: Just pasting this here as I found this patent quite interesting. https://patents.google.com/patent/US4783757A/en

Am I missing something? This is also just two layers of carry-save adders.