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The THROBAC and Jim’s MacAbacus are great - but more seriously, there is a useful discussion on the origins of the abacus in Williams, M. R. 1985. A History of Computing Technology. Englewood Cliffs: Prentice-Hall, Inc. - pp 53-66.
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<div class="">Williams focuses mainly on the table abacus used by the Greeks and Romans - not the hand abacus discussed in this intriguing blog post, which I did not know about. </div>
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<div class="">On p 56, Williams reproduces a drawing of the Greek abacus in use, copied from an ancient vase. Williams is referring to the obvious table abacus in the drawing — but the man in that same drawing is holding something in one hand that might conceivably
be a hand abacus like the one Herbert identifies. No further information is given. </div>
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<div class="">Herbert, please let us know what you find out!</div>
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<div class="">Best,</div>
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<div class="">Paul</div>
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<div class="">On Feb 20, 2019, at 12:36, <a href="mailto:herbert.bruderer@bluewin.ch" class="">
herbert.bruderer@bluewin.ch</a> wrote:</div>
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<p class=""><b style="mso-bidi-font-weight:normal" class=""><span lang="EN-US" style="margin: 0px;" class=""><font face="trebuchet ms,sans-serif" class="">How did the Romans calculate?</font></span></b></p>
<p class=""><span lang="EN-US" style="margin: 0px;" class=""><font face="trebuchet ms,sans-serif" class=""><a href="https://cacm.acm.org/blogs/blog-cacm/234881-how-did-the-romans-calculate/fulltext" class=""><font color="#0000ff" class="">https://cacm.acm.org/blogs/blog-cacm/234881-how-did-the-romans-calculate/fulltext</font></a> </font></span></p>
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<p class="">Hi all:</p>
<p class="">Does anyone know how the Romans calculated with the Roman numeral system?</p>
<p class="">What is the meaning of the right-most slot of the Roman hand abacus?</p>
<p class="">Do you have Roman hand abaci (original devices or replicas) in your collection? </p>
<p class="">Thank you very much for your help.</p>
<p class="">Best wishes,</p>
<p class="">Herbert Bruderer</p>
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___________________________<br class="">
Paul N. Edwards<br class="">
William J. Perry Fellow in International Security<br class="">
<a href="http://cisac.fsi.stanford.edu/" class="">Center for International Security and Cooperation</a><br class="">
Stanford University<br class="">
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Professor of <a href="http://www.si.umich.edu/" class="">Information</a> and <a href="http://www.lsa.umich.edu/history/" class="">History</a> (Emeritus)</div>
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University of Michigan<br class="">
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Contact:<br class="">
m: <a href="mailto:pedwards@stanford.edu" class="">pedwards@stanford.edu</a> <br class="">
w: <a href="http://pne.people.si.umich.edu" class="">pne.people.si.umich.edu</a><br class="">
t: @AVastMachine</div>
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