page_title: Computer
section_title: Pre-20th century
hierarchical_section_title: Computer / History / Pre-20th century
caption_attribution_description: Français&#160;: Fragment principal de la machine d'Anticythère. Le mécanisme consiste en un système complexe de 32 roues et plaques portant des inscriptions relatives aux signes du zodiaque et aux mois. L'étude des fragments suggère qu'il s'agissait d'une sorte d'astrolabe utilisée pour la navigation maritime. L'interprétation désormais généralement acceptée remonte aux études du professeur Derek de Solla Price, qui fut le premier à suggérer que le mécanisme est une machine à calculer le calendrier solaire et lunaire, c'est-à-dire une machine ingénieuse pour déterminer le temps sur la base des mouvements du soleil et de la lune, leur relation (éclipses) et les mouvements des autres étoiles et des planètes connues à cette époque. Le mécanisme fut probablement construit par un mécanicien ingénieux de l'école de Poséidonios à Rhodes. Cicéron, qui visita l'île en 79/78 a. C. rapporte que de tels engins étaient en effet conçus par le philosophe stoïcien Poséidonios d'Apamée. La conception du mécanisme d'Anticythère paraît suivre la tradition du planétarium d'Archimède, et peut être reliée aux cadrans solaires. Son mode opératoire est basé sur l'utilisation de roues dentées. La machine est datée de 89 avant J.-C. environ et provient de l'épave trouvée au large de l'île d'Anticythère. Musée archéologique national, Athènes, n°15987. Español: Fragmento principal de la máquina de Anticitera. El mecanismo consiste en un sistema complejo de 32 ruedas y placas con inscripciones relativas a los signos del zodiaco, meses, eclipses y juegos pan-Helénicos. El estudio de los fragmentos sugiere que se trataba de una especie de astrolabio utilizado para la navegación marítima. La interpretación más aceptada procede de los estudios del profesor Derek de Solla Price, que fue el primero en sugerir que el mecanismo es una calculadora del calendario solar y lunar, es decir, una máquina ingeniosa para determinar el tiempo basándose a los movimientos del sol y de la luna, su relación (eclipses) y los movimientos de otros planetas y estrellas conocidos en esa época. El mecanismo fue construido, probablemente, por un ingeniero mecánico de la escuela de Poséidonios en Rhodes. Cicerón, quien visitó la isla en el 79/78 a. C., cuenta que tales ingenios fueron, en efecto, concebidos por el filósofo Poseidonios de Apamea. La concepción del mecanismo de Anticitera parece seguir la tradición del planetario de Arquímedes, y puede estar relacionado con los cuadrantes solares. Su funcionamiento está basado en el uso de ruedas dentadas. La máquina data del 89 a. C. aproximadamente, y proviene del naufragio encontrado en la isla de Anticitera. Museo Arqueológico Nacional, Atenas, n°15987. English: Main w:en:Antikythera mechanism fragment (fragment A). The mechanism consists of a complex system of 30 wheels and plates with inscriptions relating to signs of the zodiac, months, eclipses and pan-Hellenic games. The study of the fragments suggests that this was a kind of astrolabe. The interpretation now generally accepted dates back to studies by Professor w:en:Derek de Solla Price, who was the first to suggest that the mechanism is a machine to calculate the solar and lunar calendar, that is to say, an ingenious machine to determine the time based on the movements of the sun and moon, their relationship (eclipses) and the movements of other stars and planets known at that time. Later research by the Antikythera Mechanism Research Project and scholar Michael Wright has added to and improved upon Price's work. The mechanism was probably built by a mechanical engineer of the school of Posidonius in Rhodes. Cicero, who visited the island in 79/78 B.C. reported that such devices were indeed designed by the Stoic philosopher Posidonius of Apamea. The design of the Antikythera mechanism appears to follow the tradition of Archimedes' planetarium, and may be related to sundials. His modus operandi is based on the use of gears. The machine is dated around 89 B.C. and comes from the wreck found off the island of Antikythera. National Archaeological Museum, Athens, No. 15987.
context_page_description: A computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. Modern computers have the ability to follow generalized sets of operations, called programs. These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware, the operating system, and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.
  Computers are used as control systems for a wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave ovens and remote controls, factory devices such as industrial robots and computer-aided design, and also general purpose devices like personal computers and mobile devices such as smartphones. The Internet is run on computers and it connects hundreds of millions of other computers and their users.
  Early computers were only conceived as calculating devices.
context_section_description: Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example.
  The abacus was initially used for arithmetic tasks. The Roman abacus was developed from devices used in Babylonia as early as 2400 BC. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money.
  The Antikythera mechanism is believed to be the earliest mechanical analog "computer", according to Derek J. de Solla Price. It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to c. 100 BC. Devices of a level of complexity comparable to that of the Antikythera mechanism would not reappear until a thousand years later.
  Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī in the early 11th century. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BC and is often attributed to Hipparchus. A combination of the planisphere and dioptra, the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235. Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe, an early fixed-wired knowledge processing machine with a gear train and gear-wheels, c. 1000 AD.
  The sector, a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation.
  The planimeter was a manual instrument to calculate the area of a closed figure by tracing over it with a mechanical linkage.
  The slide rule was invented around 1620–1630, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Slide rules with special scales are still used for quick performance of routine calculations, such as the E6B circular slide rule used for time and distance calculations on light aircraft.
  In the 1770s, Pierre Jaquet-Droz, a Swiss watchmaker, built a mechanical doll (automaton) that could write holding a quill pen. By switching the number and order of its internal wheels different letters, and hence different messages, could be produced. In effect, it could be mechanically "programmed" to read instructions. Along with two other complex machines, the doll is at the Musée d'Art et d'Histoire of Neuchâtel, Switzerland, and still operates.
  In 1831–1835, mathematician and engineer Giovanni Plana devised a Perpetual Calendar machine, which, though a system of pulleys and cylinders and over, could predict the perpetual calendar for every year from AD 0 (that is, 1 BC) to AD 4000, keeping track of leap years and varying day length. The tide-predicting machine invented by Sir William Thomson in 1872 was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels
caption: The Antikythera mechanism, dating back to ancient Greece circa 150–100 BC, is an early analog computing device.
exif: {"Image ImageDescription": "OLYMPUS DIGITAL CAMERA", "Image Make": "OLYMPUS CORPORATION", "Image Model": "C8080WZ", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS Macintosh", "Image DateTime": "2005:12:20 12:18:02", "Image YCbCrPositioning": "Co-sited", "Image PrintIM": "[80, 114, 105, 110, 116, 73, 77, 0, 48, 50, 53, 48, 0, 0, 20, 0, 1, 0, 20, 0, ... ]", "Image ExifOffset": "544", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1238", "Thumbnail JPEGInterchangeFormatLength": "8240", "EXIF ExposureTime": "1/13", "EXIF FNumber": "12/5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "125", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2005:12:19 10:15:44", "EXIF DateTimeDigitized": "2005:12:19 10:15:44", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "5/2", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "71/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "1036", "EXIF ExifImageLength": "924", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "Low gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}