The 2,100-year-old Antikythera Mechanism - with some 30 bronze gears - was known to have been used to calculate phases of the moon, eclipses and other celestial movements.
But experts from Britain, Greece and the United States said they discovered a tiny inscription of the word "Olympia" on one of the device's bronze dials, as well as the names of other games in ancient Greece, according to the report published in the science journal Nature.
The findings suggest the dates of Greece's ancient games, which held religious significance, were also used as an important time reference, said Yanis Bitsakis, a research team leader who discussed the project with The Associated Press.
"We were astonished because this is not an astronomic cycle but an Olympian cycle, one of social events," Bitsakis told the AP. "One does not need a piece of high technology to keep track of a simple four-year cycle."
Instead, he said, the mechanism might have been seen as "a microcosm illustrating the temporal harmonization of human and divine order."
The Antikythera Mechanism was accidentally discovered by sponge divers and recovered from an ancient shipwreck in 1901 near Antikythera, an island north of Crete.
Its insides looked like those of a clock, with dials on the front and back displaying the results of its calculations on celestial events. But the workings of the lunch box-sized gadget, which no longer has any functioning parts, only came to light with recent advances in scanning technology and computer processing power.
An 8-ton X-ray tomography machine was brought from Britain to the National Archaeological Museum of Athens in 2005 to scan the device's corroded and sediment-encrusted remains.
The scanner allowed scientists to peer into razor-thin sections of the device's 80-odd surviving fragments to understand its mechanics and read hundreds of tiny Greek inscriptions.
"It's like a medical scanner, but instead of putting people in it, we put the Antikythera Mechanism," said Bitsakis, of Athens University's Center for History and Palaeography.
"The inscriptions are in very faint layers, like one-tenth of a millimeter in depth, and the letters are 1 millimeter high, so it's almost nothing," he said.
The researchers found that the gear structure - including the number of teeth cut into the wheels - corresponded to known theories of celestial cycles.
They also found that the names of the months etched onto the Antikythera Mechanism were consistent with those used in Corinthian colonies in Sicily, according to their report.
The scientists said this implied a possible connection with the Greek mathematician Archimedes, who died there in 212 B.C., about 100 years before the device was probably built.
"This is an interesting, not direct link, but possible link, with the town where Archimedes used to work. It is the first link of this kind," Bitsakis said.
Information was also gleaned using another technique of making composites from high-resolution digital photographs taken of the mechanism fragments under varied lighting conditions.
Bitsakis said computer improvements, including better memory processing power and more powerful graphic cards, also made the latest discoveries possible by allowing for existing scans and images to be analyzed more extensively.
"Without this we couldn't see the inscription because you have to increase the resolution and the result is a very big file," Bitsakis said.
The ongoing research project into the Antikythera Mechanism is being led by Mike Edmunds, professor of astrophysics, and his colleagues at Cardiff University in Britain.