- Mechanical computer
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A mechanical computer is 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 examples can carry out multiplication and division, and even differential analysis.
Mechanical computers reached their zenith during World War II, when they formed the basic 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. In the post-war era, most complex examples were quickly replaced by electronic versions, an evolution that culminated in the 1970s with the introduction of inexpensive handheld electronic calculators.
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 manned spaceflight until 2002, every manned 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.
Examples
- The Antikythera mechanism, ca. 150 BC
- Jacquard Loom, 1801 – Not strictly a computer, but played an important role in the development of punched cards as input media.
- 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.
- Kerrison Predictor ("late 1930s" ?)
- Curta calculator, 1948
- Moniac, 1949 – An analog computer used to model or simulate the UK economy.
- Voskhod Spacecraft "Globus" IMP navigation instrument, early 1960s
Electro-mechanical computers
- main: Category:Electro-mechanical computers
Early electrically powered computers constructed from switches and relays rather than vacuum tubes (thermionic valves) or transistors (from which later electronic computers were constructed) are classified as electro-mechanical computers. Examples include:
- Z2, 1939
- Z3, 1941 – Designed by Konrad Zuse.
- Harvard Mark I, 1944 – Built by IBM. ("electro-mechanical counters")
- Harvard Mark II, 1947 ("electromagnetic relays")
- "Binary Arithmetic Relay Calculator" BARK, 1950
- Simon (computer), 1950
- University of Toronto Electronic Computer (UTEC), 1951
- "Binary Electronic Sequence Calculator" BESK, 1953
- "Harry Porter's Relay Computer", 2005
Defining characteristics of some early digital computers of the 1940s (In the history of computing hardware) Name First operational Numeral system Computing mechanism Programming Turing complete Zuse Z3 (Germany) May 1941 Binary floating point Electro-mechanical Program-controlled by punched 35 mm film stock (but no conditional branch) Yes (1998) Atanasoff–Berry Computer (US) 1942 Binary Electronic Not programmable—single purpose No Colossus Mark 1 (UK) February 1944 Binary Electronic Program-controlled by patch cables and switches No Harvard Mark I – IBM ASCC (US) May 1944 Decimal Electro-mechanical Program-controlled by 24-channel punched paper tape (but no conditional branch) No Colossus Mark 2 (UK) June 1944 Binary Electronic Program-controlled by patch cables and switches No Zuse Z4 (Germany) March 1945 Binary floating point Electro-mechanical Program-controlled by punched 35 mm film stock Yes ENIAC (US) July 1946 Decimal Electronic Program-controlled by patch cables and switches Yes Manchester Small-Scale Experimental Machine (Baby) (UK) June 1948 Binary Electronic Stored-program in Williams cathode ray tube memory Yes Modified ENIAC (US) September 1948 Decimal Electronic Read-only stored programming mechanism using the Function Tables as program ROM Yes EDSAC (UK) May 1949 Binary Electronic Stored-program in mercury delay line memory Yes Manchester Mark 1 (UK) October 1949 Binary Electronic Stored-program in Williams cathode ray tube memory and magnetic drum memory Yes CSIRAC (Australia) November 1949 Binary Electronic Stored-program in mercury delay line memory Yes See also
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