Building logic gates from domino

Do you feel boring ? Try to build computer from dominos :-). It's at least theoretically possible to do it, but of course practically unfeasible. Practically it's feasible to build some primitive logic circuits from dominos. It is challenging and fun, because domino system is highly unstable so it is hard to construct 100% deterministic logic functions from it. We will try to build AND logic gate here. According to wikipedia it's easy to build OR and XOR gates like that:

So AND gate can be composed from these two gate types as wiki states by formula:

A AND B = (A OR B) XOR (A XOR B)

But here we have two problems:

• We need many parts of dominos, because according to formula we need 2 XOR gates and 1 OR gates. Besides XOR gate is relatively big.
• Also as wiki states that XOR gate is extremely dependent on timing. So because we have 2 XOR gates here - dependence on timing will increase too.

This means that AND gate constructed by that scheme is highly unstable and/or needs many domino parts. Of course we can try to think about new XOR gate design from the ground-up, but still we would need 3 gates and also it is not in the scope of this article (maybe we will try to construct XOR gate in some future article). So what is left ? Answer is - we will try to construct AND gate from the ground-up with better stability and with less domino parts needed. After some thinking and trial/error process I came to such AND gate design:

Well my scheme has it's own instability which has dependence on distance between dominos. But in my opinion distance can be more easily adjusted than timing between two events without any external devices ;-) So this is how my domino AND logic gate performs in live environment:

And here is an example schema how NOT gate could be built:

Have fun with domino computing ! :-)