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Tube chip: This scanning electron microscopy image shows a section of the first-ever carbon nanotube computer. The image was colored to identify different parts of the chip.

For the first time, researchers have built a computer whose central processor is based entirely on carbon nanotubes, a 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. The computer, described today in the journal Nature, runs a simple software instruction set called MIPS. It can switch between multiple tasks (counting and sorting numbers) and keep track of them, and it can fetch data from and send it back to an external memory.

The nanotube processor is made up of 142 transistors, each of which contains carbon nanotubes that are about 10 to 200 nanometer long. The Stanford group says it has made six versions of carbon nanotube computers, including one that can be connected to external hardware—a numerical keypad that can be used to input numbers for addition.

MIT Technology Review: The First Carbon Nanotube Computer