For the first time, researchers have built a computer whose central processor is based entirely on carbon nanotubes, an incredibly tiny form of carbon with remarkable material and electronic properties. The computer is slow and simple, but its creators, a group of Stanford University engineers, say it shows that carbon nanotube electronics are a viable potential replacement for silicon when it reaches its limits in ever-smaller electronic circuits.

The carbon nanotube processor is comparable in capabilities to the Intel 4004, that company’s first microprocessor, which was released in 1971, says Subhasish Mitra, an electrical engineer at Stanford and one of the project’s co-leaders.