The Antikythera mechanism is the oldest known computer. It was discovered in 1900 when a group of sponge divers found a sunken merchant ship in the Mediterranean Sea off the Greek island of Antikythera. A salvage expedition recovered bronze statues, marble reproductions, jewelry, and glassware from about 200 feet down. The salvaged items, covered with marine growth and severely corroded, were taken to the Greek National Archaeological Museum in Athens for cleaning and analysis. Museum technicians discovered a set of bronze gears among the remains of a shriveled wooden frame.

Archaeological examinations of other items from the merchant ship indicate that many of the items came from the islands of Cos and Rhodes. These examinations also indicated that the shipwreck occurred between 80 B.C. and 40 B.C. A number of other dating techniques indicate that the device is from approximately 80 B.C. The inscription on the device has words and logic that date to the first century B.C. In addition, the dial settings on the device mathematically point to the same time frame. Finally, a high-energy gamma radiation technique from the Oak Ridge National Laboratory used in the 1970s to examine the interior of the device dated it to the same time period.

It was not until the 1950s that the purpose of the Antikythera mechanism was fully understood. The original object was determined to be a box with dials on the outside and a complex assembly of more than 20 gear-wheels inside. The mechanism contained inscriptions describing its construction and operation, but few were readable. The Antikythera mechanism was accurately determined to be an astronomical device. It was more than a pure navigational instrument, as it appears to have computed and displayed, with a high degree of accuracy, the positions of several planets as well as the rising and setting times and phases of the moon. This calculation of the motions of stars and planets offers the first implementation of an analog computer.