ATHENS, Greece -- Imagine tossing a top-notch laptop into the sea, leaving scientists from a foreign culture to scratch their heads over its corroded remains centuries later. A Roman shipmaster inadvertently did something just like it 2,000 years ago off southern Greece, experts said late Thursday.

They claim to have identified a handful of puzzling metal scraps found in the wreck as the earliest known mechanical computing device that pinpointed astronomical events.

Known as the Antikythera Mechanism _ from the island off which the Roman ship sank _ the assemblage of cogs and wheels looks like the innards of a very badly maintained grandfather clock.

Only the first clockwork devices appeared more than a thousand years later in western Europe.

"It was a pocket calculator of the time," said astronomer John Seiradakis.

Seiradakis, a professor of astronomy at the University of Thessaloniki, was among an international team including British, Greek and U.S. scientists who used specially developed x-ray scanning and imaging technology to analyze the corroded bronze, revealing hidden machinery and a form of written user's manual.

"We have used the latest technology available to understand this mechanism, yet the technological quality in this mechanism puts us to shame," said project leader Mike Edmunds, professor of astronomy at Cardiff University. "If the ancient Greeks made this, what else could they do?"

Ever since its discovery a century ago, the complex mechanism has baffled scientists.

Edmunds said the 82 surviving fragments, dated to between 140-100 B.C, contain over 30 gear wheels, and "are covered with astronomical, mathematical and mechanical inscriptions."

"It was a calendar of the moon and sun, it predicted the possibility of eclipses, it showed the position of the sun and moon in the zodiac, the phase of the moon, and we believe also it may have shown the position of some of the planets, possibly just Venus and Mercury," he said.

The box-shaped mechanism _ the size of office paper and operated with a hand-crank _ could predict an eclipse to a precise hour on a specific day.

"The design of the mechanism is very wonderful, making us realize how highly technological the ancient Greek civilization was. Much more so perhaps than we thought," Edmunds said.