Yupana - hints to Andrés Chirinos Rivera's theory

I had already found a short explanation, by Chirinos himself, in two videos on Ytb channel "walter gonzales arnao" in spanish  :  http://youtu.be/zzA9hKfw-tQ and http://youtu.be/tBZRofCHts8  (and now - july 20, 2014 - I find http://youtu.be/y7MCaqMFGc0 , which didn't seem understandable to me).

But there is something more complete : see page 32 of the user manual for the TK-Yupana tool (Tk-Yupana r07, by Kunturweb) : http://kunturweb.altervista.org/tk-yupana/doc/tk-yupana-EN.pdf.

[ this version is no longer available as of July 21 2014, but the Spanish and Italian  versions are still there :  http://kunturweb.altervista.org/tk-yupana/doc/tk-yupana-ES.pdf and http://kunturweb.altervista.org/tk-yupana/doc/tk-yupana-IT.pdf ; and the english version is also on   http://es.sourceforge.jp/projects/sfnet_tk-yupana/downloads/doc/tk-yupana-EN.pdf/ ]

The document describes various known theories about the Yupana. Around page 32, begins the description of Chirinos' theory. How to perform calculations with Chirinos' system is not yet described in this version of the document.

Use :
- the board is used in the vertical position
- each row represents a power of ten, from 0 (bottom) to n-1 (n=number of rows)
- each circle in each row of the board represents a different value (from 1 to 11) from right to left
- seeds are placed in the circles only [ 0 or 1 seed in each circle, probably ]

Value of each circle in a row is as follows :

extract from:  Table 14: Chirinos' Yupana scheme



Comments  

At first glance the system doesn't seem of the most practical kind :

• requires a very precise placing of seeds,
• multiplies the opportunities of mistakes : from mispositioning, from movements of the board, and because there is no intuitive hints to the value of each circle in a cell, it is difficult [at least for slightly dyslexic people] to remember the value of each circle, ...
• actually, this last point is not so important - see below some easily memorized configurations - when you memorize the configurations of simple numbers, you don't really need to memorize the value of the cells (sort of).
• collaborative calculus is less easy (several people seated around a board, each with a differing view of it, will have more difficulty - than with various other systems - to know the value of the seeds),
• requires a rather carefully crafted board : using an improvised earthy or sandy surface as a board is almost impossible,
• performing a multiplication with one board only and without knowing the tables doesn't seem allowed easily.

[ update 2014-03-10 : I tried with a big multiplication : rather interesting   http://youtu.be/m3n6QhZslLc 

]