Thanks to Kio, who told me how to build a
majority gate with three resistors and a CMOS
logic gate, how to build a carry chain with
such gates, and how to turn a majority gate
into a configurable AND/OR gate.
Kio, good luck with your hobby projects.
Didn't pay much attention to majority gates
before this, but because the practical use of
such gates suddenly became obvious to me,
I decided to take a closer look.
For more info about how to use majority gates,
please consult/dissect publications about
quantum dot cellular automata.
(c) Dieter Mueller 2009