At least in the flying-robot space, I think cheap batteries and sensors have been at least as important.<p>The sensors -- primarily accelerometers -- are etched in silicon, and benefit from a lot of the same cost and quality improvements as other microelectronics.<p>Batteries don&#x27;t get better as fast as processors, but they do get better. About 7% per year for the past two decades. That has been adding up, and finally tipped us over the point where you can have your own tiny flying helicopter for $15.