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. These machines could also perform more complex tasks like multiplication and division, and some were even able to 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 for ship computations with devices like the US Torpedo Data Computer or the British Admiralty Fire Control Table.

Even in space, mechanical computers were important. 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 the Globus instrument to show the movement of the Earth. These instruments displayed information using a small terrestrial globe and indicators for latitude and longitude.

Though mechanical computers were widely used into the 1960s, they began to be replaced by digital computers and later by electronic calculators. By the 1980s, they were rarely used. However, in 2016, NASA planned 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 interesting mechanical computers from history:

• Antikythera mechanism, around 100 BC – an early mechanical astronomical clock.
• Cosmic Engine, 1092 – Su Song's hydro-mechanical clock tower from the Song dynasty.
• Castle clock, 1206 – Al-Jazari's early hydropowered mechanical astronomical clock.
• The Astrarium, built in 1348 by Giovanni Dondi dell'Orologio, could show the positions of the sun, moon, stars, and planets.
• Pascaline, 1642 – Blaise Pascal's machine for adding and subtracting numbers.
• Stepped Reckoner, 1672 – Gottfried Wilhelm Leibniz's calculator for adding, subtracting, multiplying, and dividing.
• Difference Engine, 1822 – Charles Babbage's device for calculating math problems.
• Analytical Engine, 1837 – Charles Babbage's design that had many features of modern computers.
• Odhner Arithmometer, 1873 – W. T. Odhner's popular calculator.
• Ball-and-disk integrator, 1886 – used to measure tide heights.
• Dumaresq, 1902 – a Royal Navy computer for aiming weapons.
• Percy Ludgate's Analytical Machine, 1909 – one of two mechanical analytical engines designed.
• Dreyer Fire Control Table, 1911 – Royal Navy computer for aiming weapons.
• Marchant Calculator, 1918 – an advanced mechanical calculator designed by Carl Friden.
• Admiralty Fire Control Table, 1922 – an advanced Royal Navy computer for aiming weapons.
• István Juhász Gamma-Juhász (early 1930s) – a gun director.
• Kerrison Predictor – used in the 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 – a small, portable mechanical calculator.
• MONIAC, 1949 – an analog computer for modeling the UK economy.
• Voskhod Spacecraft "Globus" IMP navigation instrument, early 1960s.
• Digi-Comp I, 1963 – an educational digital computer.
• Digi-Comp II, mid-1960s – a digital computer using a rolling ball.
• Automaton – mechanical devices that can store data and perform calculations.
• Turing Tumble, 2017 – an educational computer inspired by the Digi-Comp II.
• Slide calculator, around 1845 – also called Addiator, a machine for adding and subtracting using a carry mechanism.

Punch card data processing

Main article: Unit record equipment

Before electronic computers were invented, people used special machines called unit record equipment to handle large amounts of information. These machines used punchcards — flat cards with holes punched in them — to store data, with each card holding one piece of information. By the late 1800s, these machines could add, subtract, and even multiply numbers by moving the cards through different machines in a planned order. This way, big tasks like counting and organizing data could be done quickly, even before modern computers existed. These machines were very important in businesses and governments for many years.

Electro-mechanical computers

Main category: Electro-mechanical computers

Early electrically powered computers were made using 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 special math. Even though later computers were faster, some of these older machines were kept because they were very reliable. Certain models were made in duplicate to check for mistakes, and a few were sold to the public, though many were unique experimental designs.