I’ve been reading Neal Stephenson’s <i>D.O.D.O.</i>, which refers to these quipu as similar to, but not quite the same as, the more subtle calculating devices used in the story to assess timeline incursions. Searching all the other words he and his co-author used to describe them yields “calculator”. Did Stephenson extrapolate from the quipu or is it fundamentally different? Recording rather than analyzing?