An interesting article from The New York Times: it seams that the ancient Inca population used knoted strings -- known as khipu or quipu -- in order to encode and record information. Think about it: "a reading of the knotted string devices, if deciphered, could perhaps reveal narratives of the Inca Empire, the most extensive in America in its glory days before the Spanish conquest in 1532."

Dr. Gary Urton from Harvard suggests that "the khipu did not record information in graphic signs for words, but rather a kind of three-dimensional binary code similar to the language of today's computers. "

More:
» Dr. Urton will publish this month a book on this subject, titled "Signs of the Inka Khipu"; read the first chapter
» an interviu with Dr. Urton, published by Harvard Gazette