Limited-function early computers

The history of the modern computer begins with two separate technologies—automated calculation and programmability—but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. A few devices are worth mentioning though, like some mechanical aids to computing, which were very successful and survived for centuries until the advent of the electronic calculator, like the Sumerianabacus, designed around 2500 BC^[4] which descendant won a speed competition against a modern desk calculating machine in Japan in 1946,^[5] the slide rules, invented in the 1620s, which were carried on five Apollospace missions, including to the moon^[6] and arguably theastrolabe and the Antikythera mechanism, an ancient astronomical computer built by the Greeks around 80 BC.^[7] The Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when.^[8] This is the essence of programmability.