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+---- Thread: 3 Input Adder (/thread-15775.html)
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]](https://cdn.discordapp.com/attachments/380828198348521472/707705287666172026/2020-05-06_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]](https://cdn.discordapp.com/attachments/380828198348521472/707704965837226104/2020-05-06_23.26.15.png)
And also a fully functional vertical CCA:
![[Image: 2020-05-06_23.25.34.png]](https://cdn.discordapp.com/attachments/380828198348521472/707704965589762058/2020-05-06_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.