(from Wikipedia's article about History of computing hardware)
Several analog computers were constructed in ancient and medieval times to perform astronomical calculations. These include the Antikythera mechanism and the astrolabe from ancient Greece (c. 150–100 BC), which are generally regarded as the earliest known mechanical analog computers.1
In Japan, Ryōichi Yazu patented a mechanical calculator called the Yazu Arithmometer in 1903. It consisted of a single cylinder and 22 gears, and employed the mixed base-2 and base-5 number system familiar to users to the soroban (Japanese abacus).
|Zuse Z3||Ger.||May 1941||Bin. float pt||Electro-mech|
|Colossus Mk 1||UK||Feb 1944||Binary||Electronic|
1. Lazos 1994, The Antikythera Computer
2. Jones, Douglas W, The University of Iowa
3. John Markoff (7 November 2011) "It started digital wheels turning" New York Times description of Babbage's Analytical Engine