Issue No. 03 - July-September (1983 vol. 5)
<p>Quipus, used by the Incas during the sixteenth century, were sophisticated devices for recording and transmitting codified information. They are a part of the global history of data handling and computation. This paper describes the logical-numerical system expressed through these multicolored spatial arrays of knotted cords. included are basic ideas about the logical structures of some quipu formats and the means of encoding quantitative and nonquantitative data. Several specific examples are given of quipus containing arithmetic and logical relationships.</p>
M. Ascher, "The Logical-Numerical System of Inca Quipus," in IEEE Annals of the History of Computing, vol. 5, no. , pp. 268-278, 1983.