Understanding a 2,000 year old Greek computer

szczys writes: We attribute great thinking to ancient Greece. This is exemplified by the Antikythera Mechanism. Fragments of the mechanism were found in a shipwreck first discovered in 1900 and visited by researchers several times over the next century. It is believed to be a method of tracking the calendar and is the first known example of what are now common-yet-complicated engineering mechanisms like the differential gear. A few working reproductions have been produced and make it clear that whomever designed this had an advanced understanding of complex gear ratios and their ability to track the passage of time and celestial bodies.