Two thousands years ago, the Greeks had an analogue computer called the Antikythera Mechanism. It was used to predict the eclipses, work positions of the 5 planets you can see by the naked eye (Mercury, Venus, Mars, Jupiter, Saturn) and used to calculate the 4 year cycle of the Olympic Games.
For decades, the Antikythera Mechanism lay silently in the ocean off Greece. Divers retrieved it in 1901 from the Antikythera shipwreck off the Greek island of Antikythera, which in antiquity was known as Aigila.
The Anitikythera is the same size of a clock that would stand on a mantle piece. It has a number of gears that worked together to show celestial time.
Parts of the Anitikythera can be seen in the National Archaeological Museum, in Athen which also has some reconstructions to give an impression of how the ‘computer’ worked 2000 years ago.