Light and air could easily penetrate to this point, so the works were 
contained within vacuoles—airless buckminsterfullerene shells overlaid 
with a reflective aluminum layer so that they would not implode en masse 
whenever the page was exposed to sunlight. The interiors of the 
buckyballs, then, constituted something close to a eutactic environment. Here resided the 
rod logic that made the paper smart. Each of these spherical computers was 
linked to its four neighbors, north-east-south-west, by a bundle of
flexible pushrods running down a flexible, evacuated buckytube, so that the 
page as a whole constituted a parallel computer made up of about a billion 
separate processors. The individual processors weren't especially smart or fast 
and were so susceptible to the elements that typically only a small fraction of 
them were working, but even with those limitations the smart paper still
constituted, among other things, a powerful graphical computer.