Incas Used Binary?

Abhijeet Chavan writes "An article in the Independent reports that a leading scholar believes the Incas may have used a form of binary code 500 years before computers were invented. 'Gary Urton, professor of anthropology at Harvard University, has re-analysed the complicated knotted strings of the Inca - decorative objects called khipu - and found they contain a seven-bit binary code capable of conveying more than 1,500 separate units of information...If Professor Urton is right, it means the Inca not only invented a form of binary code more than 500 years before the invention of the computer, but they used it as part of the only three-dimensional written language.'"