Mechanical computer

Mechanical computers can be either analog, using continuous or smooth mechanisms such as curved plates or slide rules for computations; or discrete, which use mechanisms like pinwheels and gears.

Mechanical computers reached their zenith during World War II, when they formed the basis of complex bombsights including the Norden, as well as the similar devices for ship computations such as the US Torpedo Data Computer or British Admiralty Fire Control Table. Noteworthy are mechanical flight instruments for early spacecraft, which provided their computed output not in the form of digits, but through the displacements of indicator surfaces. From Yuri Gagarin's first spaceflight in 1961 until 2002, every crewed Soviet and Russian spacecraft Vostok, Voskhod and Soyuz was equipped with a Globus instrument showing the apparent movement of the Earth under the spacecraft through the displacement of a miniature terrestrial globe, plus latitude and longitude indicators.

Mechanical computers continued to be used into the 1960s, but had steadily been losing ground to digital computers since their advent. By the mid-1960s dedicated electronic calculators with cathode-ray tube output emerged. The next step in the evolution occurred in the 1970s, with the introduction of inexpensive handheld electronic calculators. The use of mechanical computers declined in the 1970s and was rare by the 1980s. According to a mechanical engineer who operated the German corvette Hiddensee while it was examined by the United States Navy, the Soviets still made use of mechanical computers to calculate the target coordinates for their missiles in the late 80s.

In 2016, NASA announced that its Automaton Rover for Extreme Environments program would use a mechanical computer to operate in the harsh environmental conditions found on Venus.

Examples

• Antikythera mechanism, c. 100 BC – A mechanical astronomical clock.
• Cosmic Engine, 1092 – Su Song's hydro-mechanical astronomical clock tower invented during the Song dynasty, which featured the use of an early escapement mechanism applied to clockwork.
• Castle clock, 1206 – Al-Jazari's castle clock, a hydropowered mechanical astronomical clock, has been described as the earliest programmable analog computer.
• The Astrarium was a complex astronomical clock built in 1348 by Giovanni Dondi dell'Orologio. The Astrarium had seven faces and 107 moving parts; it could show and predict the positions of the sun, the moon, stars and the five planets then known, as well as religious feast days.
• Pascaline, 1642 – Blaise Pascal's arithmetic machine primarily intended as an adding machine which could add and subtract two numbers directly, as well as multiply and divide by repetition.
• Stepped Reckoner, 1672 – Gottfried Wilhelm Leibniz's mechanical calculator that could add, subtract, multiply, and divide.
• Difference Engine, 1822 – Charles Babbage's mechanical device to calculate polynomials.
• Analytical Engine, 1837 – A later Charles Babbage device that could be said to encapsulate most of the elements of modern computers.
• Odhner Arithmometer, 1873 – W. T. Odhner's calculator who had millions of clones manufactured until the 1970s.
• Ball-and-disk integrator, 1886 – William Thomson used it in his Harmonic Analyser to measure tide heights by calculating coefficients of a Fourier series.
• Algebraic Machines, 1893 – Leonardo Torres Quevedo's analog calculating machines designed to solve algebraic equations and find roots of polynomials. They featured the Endless Spindle (Huso sin fin), a mechanism used to calculate logarithms mechanically with high precision.
• Dumaresq, 1902 – Royal Navy fire control computer
• Percy Ludgate's 1909 Analytical Machine – The 2nd of only two mechanical Analytical Engines ever designed.
• Dreyer Fire Control Table, 1911 – Royal Navy fire control computer
• Marchant Calculator, 1918 – Most advanced of the mechanical calculators. The key design was by Carl Friden.
• Admiralty Fire Control Table, 1922 – Royal Navy advanced fire control computer.
• István Juhász Gamma-Juhász (gun director) (early 1930s)
• Kerrison Predictor ("late 1930s"?)
• Z1, 1938 (ready in 1941) – Konrad Zuse's mechanical calculator (although part imprecisions hindered its function)
• Mark I Fire Control Computer, deployed by the United States Navy during World War II (1939 to 1945) and up to 1969 or later.
• Curta calculator, 1948
• MONIAC, 1949 – An analog computer used to model or simulate the UK economy.
• Voskhod Spacecraft "Globus" IMP navigation instrument, early 1960s
• Digi-Comp I, 1963 – An educational 3-bit digital computer
• Digi-Comp II, mid 1960s – A rolling ball digital computer
• Automaton – Mechanical devices that, in some cases, can store data and perform calculations, and perform other complicated tasks.
• Turing Tumble, 2017 – An educational Turing-complete computer partially inspired by the Digi-Comp II.
• Slide calculator, around 1845 - Also known as Addiator, is a mechanical calculator capable of addition and subtraction using a carry mechanism.