This 2-bit adder was a lot of work to build. It uses a total of thirty-six 555 timers and it does have the option of adding or subtracting numbers. It’s a rather unorthodox use of the part ...

The adder looks complicated, but it really is just a half-adder and full-adder piped together in exactly the same way it would be wired up with CMOS or TTL gates. The video below shows it in action.

When assembled into 3D cultures, these engineered cell consortia execute programmable multicellular full-adder logics in response to three trigger compounds. You have full access to this article ...