Mechanical computer

A mechanical computer is a computer built from mechanical components such as levers and gears rather than electronic components. The most common examples are adding machines and mechanical counters, which use the turning of gears to increment output displays. More complex machines could even carry out multiplication, division, and differential analysis. One famous model, the Ascota 170 accounting machine sold in the 1960s, could calculate square roots.

Mechanical computers can be analog, using smooth mechanisms such as curved plates or slide rules, or discrete, using mechanisms like pinwheels and gears. They reached their peak during World War II, when they were used in important tools such as bombsights, including the Norden, and ship computation devices like the US Torpedo Data Computer or British Admiralty Fire Control Table. Even early spacecraft relied on mechanical computers. From Yuri Gagarin's first spaceflight in 1961 until 2002, every crewed Soviet and Russian spacecraft, including Vostok, Voskhod, and Soyuz, used a special instrument called Globus to show the movement of the Earth.

Though mechanical computers were widely used into the 1960s, they gradually lost popularity as digital computers and electronic calculators became more common. By the 1980s, mechanical computers were rarely used. However, in 2016, NASA announced plans to use a mechanical computer for its Automaton Rover for Extreme Environments program, designed to work in the extreme conditions on Venus.

Examples

Here are some famous mechanical computers from history:

• Antikythera mechanism, around 100 BC – An early astronomical clock.
• Cosmic Engine, 1092 – Su Song's hydro-mechanical clock tower from the Song dynasty.
• Castle clock, 1206 – Al-Jazari's hydropowered astronomical clock, considered one of the earliest programmable machines.
• The Astrarium, 1348 – A complex astronomical clock built by Giovanni Dondi dell'Orologio that could show positions of celestial bodies.
• Pascaline, 1642 – Blaise Pascal's machine for adding and subtracting numbers.
• Stepped Reckoner, 1672 – Gottfried Wilhelm Leibniz's calculator for basic math operations.
• Difference Engine, 1822 – Charles Babbage's device for calculating polynomials.
• Analytical Engine, 1837 – Charles Babbage's advanced design close to modern computers.
• Odhner Arithmometer, 1873 – W. T. Odhner's widely produced calculator.
• Ball-and-disk integrator, 1886 – Used by William Thomson for scientific calculations.
• Dumaresq, 1902 – A Royal Navy computer for aiming weapons.
• Percy Ludgate's 1909 Analytical Machine – One of two mechanical Analytical Engines designed.
• Dreyer Fire Control Table, 1911 – Royal Navy computer for weapon aiming.
• Marchant Calculator, 1918 – An advanced mechanical calculator designed by Carl Friden.
• Admiralty Fire Control Table, 1922 – Advanced Royal Navy fire control computer.^{[dubious – discuss]}
• István Juhász Gamma-Juhász (gun director), early 1930s
• Kerrison Predictor, late 1930s
• Z1, 1938 – Konrad Zuse's early mechanical calculator.
• Mark I Fire Control Computer, used by the United States Navy during World War II.
• Curta calculator, 1948
• MONIAC, 1949 – An analog computer for modeling the UK economy.
• Voskhod Spacecraft "Globus" IMP navigation instrument, early 1960s
• Digi-Comp I, 1963 – A simple educational digital computer.
• Digi-Comp II, mid-1960s – A rolling ball digital computer.
• Automaton – Mechanical devices capable of storing data and performing calculations.
• Turing Tumble, 2017 – An educational computer inspired by the Digi-Comp II.
• Slide calculator, around 1845 – Also known as Addiator, a mechanical calculator for addition and subtraction.

Punch card data processing

Main article: Unit record equipment

Before electronic computers existed, people used special machines called unit record equipment to handle large amounts of data. These machines used punchcards, which were cards with holes punched in them to represent information. Each card held details about one item, like a person or a product. By the late 1800s, inventor Herman Hollerith created a way to record and organize census information using these cards.

These machines could add, subtract, and later even multiply the data on the cards. They processed the cards quickly, sometimes up to 2,000 per minute, using sensors to read the holes. Operators could change how the machine worked by using a special plugboard, control panel, or connection box, making these tools very useful for big jobs in both businesses and governments until electronic computers became common.

Electro-mechanical computers

Main category: Electro-mechanical computers

Early electrically powered computers were made from switches and relay logic instead of vacuum tubes or transistors. These machines came in many different designs and could do various tasks, including some that used floating point arithmetic. Even though they were slower than later computers, some of these relay-based machines were still used because they were very reliable. A few of these models were made for sale with several units produced, while many others were unique experimental designs.