Most compact binary adder

[embizone]

I always under the impression that dimensions are usable dimensions (therefore the 9 long) with stacking considered (therefore the 4 tall).

That has never been the case... is my 4 wide CCA not 4 wide because you can't tile it? Of course not.

Two tall tileable adders this small are a beast. I don't normally redstone anymore, but this looks like a fun challenge. Embi, I shall give this a shot. I presume we don't care about speed?

I mentioned twice that this is trivial. Here's a design that is 2 high x 4 wide x 9 long: http://imgur.com/a/xwg9J