The paper D.S. Eom, D.M. Parichy, “A macrophage relay for long-distance signaling during postembryonic tissue remodeling,” Science, doi:10.1126/science.aal2745 ...
Built as an educational demonstrator, this is a complete arithmetic-logic unit (ALU) using discrete relays — and not high-density types either — these are the big honking clear-cased kind.