I did some contract design work for a company called Theseus (Mumble) back around 2000. Their stuff was all non-clocked logic. They used two rails per bit and depending on how the two rails were coded it represented either 0, 1 or ready (or finished?), if I remember correctly. The logic to signal back the completion and readys about doubled the amount of real estate the logic used, but it could run as fast as the gates allowed, did not have a synchronizing pulse, making remote monitoring attacks difficult to impossible and only used as much power as it needed to process the actual data available. The amount of design discipline needed was substantial, making me wonder if just going to the trouble of implementing more traditional power saving techniques wasn't a better option. Jeff Walther