121-494: Information technology ( IT ) is a set of related fields that encompass computer systems, software , programming languages , and data and information processing, and storage. IT forms part of information and communications technology (ICT). An information technology system ( IT system ) is generally an information system , a communications system , or, more specifically speaking, a computer system — including all hardware , software , and peripheral equipment — operated by
242-409: A parapegma , a precursor of the modern day almanac inscribed on the front face above and beneath the dials. They mark the locations of longitudes on the ecliptic for specific stars. The parapegma above the dials reads (square brackets indicate inferred text): The parapegma beneath the dials reads: At least two pointers indicated positions of bodies upon the ecliptic. A lunar pointer indicated
363-532: A provider and accessed over the Internet . The process of developing software involves several stages. The stages include software design , programming , testing , release , and maintenance . Software quality assurance and security are critical aspects of software development, as bugs and security vulnerabilities can lead to system failures and security breaches. Additionally, legal issues such as software licenses and intellectual property rights play
484-509: A vulnerability . Software patches are often released to fix identified vulnerabilities, but those that remain unknown ( zero days ) as well as those that have not been patched are still liable for exploitation. Vulnerabilities vary in their ability to be exploited by malicious actors, and the actual risk is dependent on the nature of the vulnerability as well as the value of the surrounding system. Although some vulnerabilities can only be used for denial of service attacks that compromise
605-520: A web application —had become the primary method that companies deliver applications. Software companies aim to deliver a high-quality product on time and under budget. A challenge is that software development effort estimation is often inaccurate. Software development begins by conceiving the project, evaluating its feasibility, analyzing the business requirements, and making a software design . Most software projects speed up their development by reusing or incorporating existing software, either in
726-650: A 1-in-76-year Callippic cycle correction, as well as convenient lunisolar intercalation. The dial also marks the position of the Sun on the ecliptic, corresponding to the current date in the year. The orbits of the Moon and the five planets known to the Greeks are close enough to the ecliptic to make it a convenient reference for defining their positions as well. The following three Egyptian months are inscribed in Greek letters on
847-616: A business context, the Information Technology Association of America has defined information technology as "the study, design, development, application, implementation, support, or management of computer-based information systems". The responsibilities of those working in the field include network administration, software development and installation, and the planning and management of an organization's technology life cycle, by which hardware and software are maintained, upgraded, and replaced. Information services
968-457: A change request. Frequently, software is released in an incomplete state when the development team runs out of time or funding. Despite testing and quality assurance , virtually all software contains bugs where the system does not work as intended. Post-release software maintenance is necessary to remediate these bugs when they are found and keep the software working as the environment changes over time. New features are often added after
1089-486: A code's correct and efficient behavior, its reusability and portability , or the ease of modification. It is usually more cost-effective to build quality into the product from the beginning rather than try to add it later in the development process. Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and easier to maintain . Software failures in safety-critical systems can be very serious including death. By some estimates,
1210-541: A complete computing machine. During the Second World War , Colossus developed the first electronic digital computer to decrypt German messages. Although it was programmable , it was not general-purpose, being designed to perform only a single task. It also lacked the ability to store its program in memory; programming was carried out using plugs and switches to alter the internal wiring. The first recognizably modern electronic digital stored-program computer
1331-639: A crew of sponge divers from Symi island discovered the Antikythera wreck in early 1900, and recovered artefacts during the first expedition with the Hellenic Royal Navy , in 1900–01. This wreck of a Roman cargo ship was found at a depth of 45 metres (148 ft) off Point Glyphadia on the Greek island of Antikythera . The team retrieved numerous large objects, including bronze and marble statues, pottery, unique glassware, jewellery, coins, and
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#17327659848921452-431: A decade later resulted in $ 289 billion in sales. And as computers are rapidly becoming more sophisticated by the day, they are becoming more used as people are becoming more reliant on them during the twenty-first century. Early electronic computers such as Colossus made use of punched tape , a long strip of paper on which data was represented by a series of holes, a technology now obsolete. Electronic data storage, which
1573-417: A hypothesis that it was constructed at an academy founded by Stoic philosopher Posidonius on that Greek island. Rhodes was a busy trading port and centre of astronomy and mechanical engineering, home to astronomer Hipparchus, who was active from about 140–120 BC. The mechanism uses Hipparchus' theory for the motion of the Moon, which suggests he may have designed or at least worked on it. It has been argued
1694-443: A legal regime where liability for software products is significantly curtailed compared to other products. Source code is protected by copyright law that vests the owner with the exclusive right to copy the code. The underlying ideas or algorithms are not protected by copyright law, but are often treated as a trade secret and concealed by such methods as non-disclosure agreements . Software copyright has been recognized since
1815-568: A limited group of IT users, and an IT project usually refers to the commissioning and implementation of an IT system. IT systems play a vital role in facilitating efficient data management, enhancing communication networks, and supporting organizational processes across various industries. Successful IT projects require meticulous planning, seamless integration, and ongoing maintenance to ensure optimal functionality and alignment with organizational objectives. Although humans have been storing, retrieving, manipulating, and communicating information since
1936-450: A more efficient manner are usually seen as "just the cost of doing business." IT departments are allocated funds by senior leadership and must attempt to achieve the desired deliverables while staying within that budget. Government and the private sector might have different funding mechanisms, but the principles are more-or-less the same. This is an often overlooked reason for the rapid interest in automation and Artificial Intelligence , but
2057-470: A more likely calibration date. Machines with similar complexity did not appear again until the fourteenth century, with early examples being astronomical clocks of Richard of Wallingford and Giovanni de' Dondi . The original mechanism apparently came out of the Mediterranean as a single encrusted piece. Soon afterwards it fractured into three major pieces. Other small pieces have broken off in
2178-473: A particular letter; possible delays in message delivery (up to several days); limits on the size of one message and on the total size of messages in the mailbox (personal for users). A software and hardware complex with a web interface that provides the ability to search for information on the Internet. A search engine usually means a site that hosts the interface (front-end) of the system. The software part of
2299-444: A quick web search . Most creative professionals have switched to software-based tools such as computer-aided design , 3D modeling , digital image editing , and computer animation . Almost every complex device is controlled by software. Antikythera mechanism The Antikythera mechanism ( / ˌ æ n t ɪ k ɪ ˈ θ ɪər ə / AN -tik-ih- THEER -ə , US also / ˌ æ n t aɪ k ɪ ˈ -/ AN -ty-kih- )
2420-405: A search engine is a search engine (search engine) — a set of programs that provides the functionality of a search engine and is usually a trade secret of the search engine developer company. Most search engines look for information on World Wide Web sites, but there are also systems that can look for files on FTP servers, items in online stores, and information on Usenet newsgroups. Improving search
2541-590: A shipwreck off the coast of the Greek island Antikythera in 1901. In 1902, it was identified by archaeologist Valerios Stais as containing a gear . The device, housed in the remains of a wooden-framed case of (uncertain) overall size 34 cm × 18 cm × 9 cm (13.4 in × 7.1 in × 3.5 in), was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear
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#17327659848922662-495: A significant role in the distribution of software products. The first use of the word software is credited to mathematician John Wilder Tukey in 1958. The first programmable computers, which appeared at the end of the 1940s, were programmed in machine language . Machine language is difficult to debug and not portable across different computers. Initially, hardware resources were more expensive than human resources . As programs became complex, programmer productivity became
2783-458: A specific version of the software, downloaded, and run on hardware belonging to the purchaser. The rise of the Internet and cloud computing enabled a new model, software as a service (SaaS), in which the provider hosts the software (usually built on top of rented infrastructure or platforms ) and provides the use of the software to customers, often in exchange for a subscription fee . By 2023, SaaS products—which are usually delivered via
2904-415: A system's availability, others allow the attacker to inject and run their own code (called malware ), without the user being aware of it. To thwart cyberattacks, all software in the system must be designed to withstand and recover from external attack. Despite efforts to ensure security, a significant fraction of computers are infected with malware. Programming languages are the format in which software
3025-448: Is 235 synodic months , which is very close (to within less than 13 one-millionths) to 19 tropical years. It is therefore a convenient interval over which to convert between lunar and solar calendars. The Metonic dial covers 235 months in five rotations of the dial, following a spiral track with a follower on the pointer that keeps track of the layer of the spiral. The pointer points to the synodic month, counted from new moon to new moon, and
3146-480: Is a term somewhat loosely applied to a variety of IT-related services offered by commercial companies, as well as data brokers . The field of information ethics was established by mathematician Norbert Wiener in the 1940s. Some of the ethical issues associated with the use of information technology include: Research suggests that IT projects in business and public administration can easily become significant in scale. Work conducted by McKinsey in collaboration with
3267-486: Is about 13 cm (5 in) in diameter and originally had 223 teeth. All these fragments of the mechanism are kept at the National Archaeological Museum, Athens , along with reconstructions and replicas , to demonstrate how it may have looked and worked. In 2005, a team from Cardiff University used computer X-ray tomography and high resolution scanning to image inside fragments of
3388-433: Is also worth noting that from a business perspective, Information technology departments are a " cost center " the majority of the time. A cost center is a department or staff which incurs expenses, or "costs", within a company rather than generating profits or revenue streams. Modern businesses rely heavily on technology for their day-to-day operations, so the expenses delegated to cover technology that facilitates business in
3509-475: Is an Ancient Greek hand-powered orrery (model of the Solar System ). It is the oldest known example of an analogue computer . It could be used to predict astronomical positions and eclipses decades in advance. It could also be used to track the four-year cycle of athletic games similar to an Olympiad , the cycle of the ancient Olympic Games . The artefact was among wreckage retrieved from
3630-402: Is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the machine language specific to the hardware. The introduction of high-level programming languages in 1958 allowed for more human-readable instructions, making software development easier and more portable across different computer architectures . Software in a programming language
3751-471: Is not one of the six values in the range 350 to 355. The chances of N being as high as 365 are less than 1 in 10,000. While other contenders cannot be ruled out, of the two values that have been proposed for N on astronomical grounds, that of Budiselic et al. (354) is by far the more likely." If one supports the 365 day presumption, it is recognized the mechanism predates the Julian calendar reform, but
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3872-504: Is one of the priorities of the modern Internet (see the Deep Web article about the main problems in the work of search engines). Companies in the information technology field are often discussed as a group as the "tech sector" or the "tech industry." These titles can be misleading at times and should not be mistaken for "tech companies;" which are generally large scale, for-profit corporations that sell consumer technology and software. It
3993-414: Is run through a compiler or interpreter to execute on the architecture's hardware. Over time, software has become complex, owing to developments in networking , operating systems , and databases . Software can generally be categorized into two main types: The rise of cloud computing has introduced the new software delivery model Software as a Service (SaaS). In SaaS, applications are hosted by
4114-613: Is still stored magnetically on hard disks, or optically on media such as CD-ROMs . Until 2002 most information was stored on analog devices , but that year digital storage capacity exceeded analog for the first time. As of 2007, almost 94% of the data stored worldwide was held digitally: 52% on hard disks, 28% on optical devices, and 11% on digital magnetic tape. It has been estimated that the worldwide capacity to store information on electronic devices grew from less than 3 exabytes in 1986 to 295 exabytes in 2007, doubling roughly every 3 years. Database Management Systems (DMS) emerged in
4235-493: Is the right secondary upper dial; it is the only pointer on the instrument that travels in an anticlockwise direction as time advances. The dial is divided into four sectors, each of which is inscribed with a year indicator and the name of two Panhellenic Games : the "crown" games of Isthmia , Olympia , Nemea , and Pythia ; and two lesser games: Naa (held at Dodona ) and the Halieia of Rhodes. The inscriptions on each one of
4356-454: Is used in modern computers, dates from World War II, when a form of delay-line memory was developed to remove the clutter from radar signals, the first practical application of which was the mercury delay line. The first random-access digital storage device was the Williams tube , which was based on a standard cathode ray tube . However, the information stored in it and delay-line memory
4477-453: Is written. Since the 1950s, thousands of different programming languages have been invented; some have been in use for decades, while others have fallen into disuse. Some definitions classify machine code —the exact instructions directly implemented by the hardware—and assembly language —a more human-readable alternative to machine code whose statements can be translated one-to-one into machine code—as programming languages. Programs written in
4598-597: The Callippic and Metonic cycles. Also written is "223" for the Saros cycle . On another one of its fragments, it is written "on the spiral subdivisions 235" referring to the Metonic dial. The mechanism is remarkable for the level of miniaturisation and the complexity of its parts, which is comparable to that of 14th-century astronomical clocks . It has at least 30 gears, although mechanism expert Michael Wright has suggested
4719-424: The Callippic cycle . Other inscriptions seem to describe the function of the back dials. In addition to this important minor fragment, 15 further minor fragments have remnants of inscriptions on them. Information on the specific data obtained from the fragments is detailed in the supplement to the 2006 Nature article from Freeth et al. On the front face of the mechanism, there is a fixed ring dial representing
4840-588: The Hellenistic period . Its construction relied on theories of astronomy and mathematics developed by Greek astronomers during the second century BC, and it is estimated to have been built in the late second century BC or the early first century BC. In 2008, research by the Antikythera Mechanism Research Project suggested the concept for the mechanism may have originated in the colonies of Corinth , since they identified
4961-482: The International Organization for Standardization (ISO). Innovations in technology have already revolutionized the world by the twenty-first century as people were able to access different online services. This has changed the workforce drastically as thirty percent of U.S. workers were already in careers in this profession. 136.9 million people were personally connected to the Internet , which
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5082-526: The Sothic and Callippic cycles had already pointed to a 365 + 1 / 4 day solar year, as seen in Ptolemy ;III 's attempted calendar reform of 238 BC. The dials are not believed to reflect his proposed leap day ( Epag. 6), but the outer calendar dial may be moved against the inner dial to compensate for the effect of the extra quarter-day in the solar year by turning
5203-478: The University of Oxford suggested that half of all large-scale IT projects (those with initial cost estimates of $ 15 million or more) often failed to maintain costs within their initial budgets or to complete on time. Software Software consists of computer programs that instruct the execution of a computer . Software also includes design documents and specifications. The history of software
5324-583: The ecliptic , the twelve zodiacal signs marked off with equal 30-degree sectors. This matched with the Babylonian custom of assigning one twelfth of the ecliptic to each zodiac sign equally, even though the constellation boundaries were variable. Outside that dial is another ring which is rotatable, marked off with the months and days of the Sothic Egyptian calendar , twelve months of 30 days plus five intercalary days . The months are marked with
5445-502: The extensible markup language (XML) has become a popular format for data representation. Although XML data can be stored in normal file systems , it is commonly held in relational databases to take advantage of their "robust implementation verified by years of both theoretical and practical effort." As an evolution of the Standard Generalized Markup Language (SGML), XML's text-based structure offers
5566-438: The high-level programming languages used to create software share a few main characteristics: knowledge of machine code is not necessary to write them, they can be ported to other computer systems, and they are more concise and human-readable than machine code. They must be both human-readable and capable of being translated into unambiguous instructions for computer hardware. The invention of high-level programming languages
5687-431: The 16th century, and it was not until 1645 that the first mechanical calculator capable of performing the four basic arithmetical operations was developed. Electronic computers , using either relays or valves , began to appear in the early 1940s. The electromechanical Zuse Z3 , completed in 1941, was the world's first programmable computer, and by modern standards one of the first machines that could be considered
5808-453: The 1960s to address the problem of storing and retrieving large amounts of data accurately and quickly. An early such system was IBM 's Information Management System (IMS), which is still widely deployed more than 50 years later. IMS stores data hierarchically , but in the 1970s Ted Codd proposed an alternative relational storage model based on set theory and predicate logic and the familiar concepts of tables, rows, and columns. In 1981,
5929-604: The 2nd century BC by astronomer Hipparchus of Rhodes , and he may have been consulted in the machine's construction. There is speculation that a portion of the mechanism is missing and it calculated the positions of the five classical planets . The inscriptions were further deciphered in 2016, revealing numbers connected with the synodic cycles of Venus and Saturn. The instrument is believed to have been designed and constructed by Hellenistic scientists and been variously dated to about 87 BC, between 150 and 100 BC, or 205 BC. It must have been constructed before
6050-405: The 82 fragments. Price published a paper on their findings in 1974. Two other searches for items at the Antikythera wreck site in 2012 and 2015 yielded art objects and a second ship which may, or may not, be connected with the treasure ship on which the mechanism was found. Also found was a bronze disc, embellished with the image of a bull. The disc has four "ears" which have holes in them, and it
6171-405: The Babylonian arithmetic style of prediction fits much better with the device's predictive models than the traditional Greek trigonometric style. A study by Iversen in 2017 reasons that the prototype for the device was from Rhodes, but that this particular model was modified for a client from Epirus in northwestern Greece; Iversen argues it was probably constructed no earlier than a generation before
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#17327659848926292-482: The Egyptian names for the months transcribed into the Greek alphabet . The first task is to rotate the Egyptian calendar ring to match the current zodiac points. The Egyptian calendar ignored leap days, so it advanced through a full zodiac sign in about 120 years. The mechanism was operated by turning a small hand crank (now lost) which was linked via a crown gear to the largest gear, the four-spoked gear visible on
6413-467: The Greeks of this period were capable of implementing a system with many more gears. There is debate as to whether the mechanism had indicators for all five of the planets known to the ancient Greeks. No gearing for such a planetary display survives and all gears are accounted for—with the exception of one 63-toothed gear (r1) otherwise unaccounted for in fragment D. Fragment D is a small quasi-circular constriction that, according to Xenophon Moussas, has
6534-458: The Sun), but there is no evidence of it among the fragments found. Similarly, neither is there the evidence of planetary orbit pointers for the five planets known to the Greeks among the fragments. But see Proposed gear schemes below. Mechanical engineer Michael Wright demonstrated there was a mechanism to supply the lunar phase in addition to the position. The indicator was a small ball embedded in
6655-417: The ability to transfer both plain text and formatted, as well as arbitrary files; independence of servers (in the general case, they address each other directly); sufficiently high reliability of message delivery; ease of use by humans and programs. Disadvantages of e-mail: the presence of such a phenomenon as spam (massive advertising and viral mailings); the theoretical impossibility of guaranteed delivery of
6776-409: The advantage of being both machine- and human-readable . Data transmission has three aspects: transmission, propagation, and reception. It can be broadly categorized as broadcasting , in which information is transmitted unidirectionally downstream, or telecommunications , with bidirectional upstream and downstream channels. XML has been increasingly employed as a means of data interchange since
6897-564: The application of statistical and mathematical methods to decision-making , and the simulation of higher-order thinking through computer programs. The term is commonly used as a synonym for computers and computer networks , but it also encompasses other information distribution technologies such as television and telephones . Several products or services within an economy are associated with information technology, including computer hardware , software , electronics, semiconductors, internet , telecom equipment , and e-commerce . Based on
7018-572: The astronomical events on the Parapegma of the mechanism work best for latitudes in the range of 33.3–37.0 degrees north; the island of Rhodes is located between the latitudes of 35.85 and 36.50 degrees north. In 2014, a study argued for a new dating of approximately 200 BC, based on identifying the start-up date on the Saros Dial, as the astronomical lunar month that began shortly after the new moon of 28 April 205 BC. According to this theory
7139-571: The back of the mechanism, there are five dials: the two large displays, the Metonic and the Saros , and three smaller indicators, the so-called Olympiad Dial, which has been renamed the Games dial as it did not track Olympiad years (the four-year cycle it tracks most closely is the Halieiad), the Callippic , and the exeligmos . The Metonic dial is the main upper dial on the rear of the mechanism. The Metonic cycle, defined in several physical units,
7260-399: The bottleneck. The introduction of high-level programming languages in 1958 hid the details of the hardware and expressed the underlying algorithms into the code . Early languages include Fortran , Lisp , and COBOL . There are two main types of software: Software can also be categorized by how it is deployed . Traditional applications are purchased with a perpetual license for
7381-687: The calendar on the Metonic Spiral as coming from Corinth, or one of its colonies in northwest Greece or Sicily. Syracuse was a colony of Corinth and the home of Archimedes , and the Antikythera Mechanism Research Project argued in 2008 that it might imply a connection with the school of Archimedes. It was demonstrated in 2017 that the calendar on the Metonic Spiral is of the Corinthian type, but cannot be that of Syracuse. Another theory suggests that coins found by Jacques Cousteau at
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#17327659848927502-529: The calendar on the mechanism is likely to be the Epirote calendar, and that this calendar was probably adopted from a Corinthian colony in Epirus, possibly Ambracia. It has been argued that the first month of the calendar, Phoinikaios, was ideally the month in which the autumn equinox fell, and that the start-up date of the calendar began shortly after the astronomical new moon of 23 August 205 BC. The Games dial
7623-538: The cell contains the Corinthian month names . Thus, setting the correct solar time (in days) on the front panel indicates the current lunar month on the back panel, with resolution to within a week or so. Based on the fact that the calendar month names are consistent with all the evidence of the Epirote calendar and that the Games dial mentions the very minor Naa games of Dodona (in Epirus), it has been argued that
7744-418: The constant pressure to do more with less is opening the door for automation to take control of at least some minor operations in large companies. Many companies now have IT departments for managing the computers , networks, and other technical areas of their businesses. Companies have also sought to integrate IT with business outcomes and decision-making through a BizOps or business operations department. In
7865-404: The correctness of code, while user acceptance testing helps to ensure that the product meets customer expectations. There are a variety of software development methodologies , which vary from completing all steps in order to concurrent and iterative models. Software development is driven by requirements taken from prospective users, as opposed to maintenance, which is driven by events such as
7986-400: The cost of poor quality software can be as high as 20 to 40 percent of sales. Despite developers' goal of delivering a product that works entirely as intended, virtually all software contains bugs. The rise of the Internet also greatly increased the need for computer security as it enabled malicious actors to conduct cyberattacks remotely. If a bug creates a security risk, it is called
8107-419: The cost of products. Unlike copyrights, patents generally only apply in the jurisdiction where they were issued. Engineer Capers Jones writes that "computers and software are making profound changes to every aspect of human life: education, work, warfare, entertainment, medicine, law, and everything else". It has become ubiquitous in everyday life in developed countries . In many cases, software augments
8228-413: The crust-encased mechanism and read the faintest inscriptions that once covered the outer casing. These scans suggest that the mechanism had 37 meshing bronze gears enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and to model the irregular orbit of the Moon , where the Moon's velocity is higher in its perigee than in its apogee . This motion was studied in
8349-473: The designated eclipse is solar or lunar, and give the day of the month and hour. Solar eclipses may not be visible at any given point, and lunar eclipses are visible only if the moon is above the horizon at the appointed hour. In addition, the inner lines at the cardinal points of the Saros dial indicate the start of a new full moon cycle . Based on the distribution of the times of the eclipses, it has been argued
8470-400: The discovery of the mechanism more than a century ago, this outer ring has been presumed to represent a 365-day Egyptian solar calendar, but research (Budiselic, et al., 2020) challenged this presumption and provided direct statistical evidence there are 354 intervals, suggesting a lunar calendar. Since this initial discovery, two research teams, using different methods, independently calculated
8591-502: The earliest writing systems were developed, the term information technology in its modern sense first appeared in a 1958 article published in the Harvard Business Review ; authors Harold J. Leavitt and Thomas L. Whisler commented that "the new technology does not yet have a single established name. We shall call it information technology (IT)." Their definition consists of three categories: techniques for processing,
8712-423: The early 2000s, particularly for machine-oriented interactions such as those involved in web-oriented protocols such as SOAP , describing "data-in-transit rather than... data-at-rest". Hilbert and Lopez identify the exponential pace of technological change (a kind of Moore's law ): machines' application-specific capacity to compute information per capita roughly doubled every 14 months between 1986 and 2007;
8833-416: The email was considered revolutionary as "companies in one part of the world could communicate by e-mail with suppliers and buyers in another part of the world..." Not only personally, computers and technology have also revolutionized the marketing industry, resulting in more buyers of their products. During the year of 2002, Americans exceeded $ 28 billion in goods just over the Internet alone while e-commerce
8954-453: The field of data mining — "the process of discovering interesting patterns and knowledge from large amounts of data" — emerged in the late 1980s. The technology and services it provides for sending and receiving electronic messages (called "letters" or "electronic letters") over a distributed (including global) computer network. In terms of the composition of elements and the principle of operation, electronic mail practically repeats
9075-427: The first commercially available relational database management system (RDBMS) was released by Oracle . All DMS consist of components, they allow the data they store to be accessed simultaneously by many users while maintaining its integrity. All databases are common in one point that the structure of the data they contain is defined and stored separately from the data itself, in a database schema . In recent years,
9196-520: The first planar silicon dioxide transistors by Frosch and Derick in 1957, the MOSFET demonstration by a Bell Labs team. the planar process by Jean Hoerni in 1959,and the microprocessor invented by Ted Hoff , Federico Faggin , Masatoshi Shima , and Stanley Mazor at Intel in 1971. These important inventions led to the development of the personal computer (PC) in the 1970s, and the emergence of information and communications technology (ICT). By
9317-442: The first transistorized computer developed at the University of Manchester and operational by November 1953, consumed only 150 watts in its final version. Several other breakthroughs in semiconductor technology include the integrated circuit (IC) invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor in 1959, silicon dioxide surface passivation by Carl Frosch and Lincoln Derick in 1955,
9438-438: The form of commercial off-the-shelf (COTS) or open-source software . Software quality assurance is typically a combination of manual code review by other engineers and automated software testing . Due to time constraints, testing cannot cover all aspects of the software's intended functionality, so developers often focus on the most critical functionality. Formal methods are used in some safety-critical systems to prove
9559-407: The four divisions are: The Saros dial is the main lower spiral dial on the rear of the mechanism. The Saros cycle is 18 years and 11 + 1 ⁄ 3 days long (6585.333... days), which is very close to 223 synodic months (6585.3211 days). It is defined as the cycle of repetition of the positions required to cause solar and lunar eclipses, and therefore, it could be used to predict them—not only
9680-442: The front of fragment A, gear b1. This moved the date pointer on the front dial, which would be set to the correct Egyptian calendar day. The year is not selectable, so it is necessary to know the year currently set, or by looking up the cycles indicated by the various calendar cycle indicators on the back in the Babylonian ephemeris tables for the day of the year currently set, since most of the calendar cycles are not synchronous with
9801-439: The functionality of existing technologies such as household appliances and elevators . Software also spawned entirely new technologies such as the Internet , video games , mobile phones , and GPS . New methods of communication, including email , forums , blogs , microblogging , wikis , and social media , were enabled by the Internet. Massive amounts of knowledge exceeding any paper-based library are now available with
9922-427: The inscriptions. The labels on its three divisions are: Thus the dial pointer indicates how many hours must be added to the glyph times of the Saros dial in order to calculate the exact eclipse times. The mechanism has a wooden casing with a front and a back door, both containing inscriptions. The back door appears to be the 'instruction manual'. On one of its fragments is written "76 years, 19 years" representing
10043-532: The interim from cleaning and handling, and others were found on the sea floor by the Cousteau expedition. Other fragments may still be in storage, undiscovered since their initial recovery; Fragment F was discovered in that way in 2005. Of the 82 known fragments, seven are mechanically significant and contain the majority of the mechanism and inscriptions. Another 16 smaller parts contain fractional and incomplete inscriptions. Fragment A also contains divisions of
10164-510: The interval count. Woan and Bayley calculate 354–355 intervals using two different methods, confirming with higher accuracy the Budiselic et al. findings and noting that "365 holes is not plausible". Malin and Dickens' best estimate is 352.3±1.5 and concluded that the number of holes (N) "has to be integral and the SE ( standard error ) of 1.5 indicates that there is less than a 5% probability that N
10285-538: The introduction of computer science-related courses in K-12 education . Ideas of computer science were first mentioned before the 1950s under the Massachusetts Institute of Technology (MIT) and Harvard University , where they had discussed and began thinking of computer circuits and numerical calculations. As time went on, the field of information technology and computer science became more complex and
10406-423: The locations of planets . The operator also had to be aware of the position of the spiral dial pointers on the two large dials on the back. The pointer had a "follower" that tracked the spiral incisions in the metal as the dials incorporated four and five full rotations of the pointers. When a pointer reached the terminal month location at either end of the spiral, the pointer's follower had to be manually moved to
10527-545: The lunar pointer, half-white and half-black, which rotated to show the phase (new, first quarter, half, third quarter, full, and back). The data to support this function is available given the Sun and Moon positions as angular rotations; essentially, it is the angle between the two, translated into the rotation of the ball. It requires a differential gear , a gearing arrangement that sums or differences two angular inputs. In 2008, scientists reported new findings in Nature showing
10648-453: The mechanism not only tracked the Metonic calendar and predicted solar eclipses , but also calculated the timing of panhellenic athletic games, such as the ancient Olympic Games . Inscriptions on the instrument closely match the names of the months that are used on calendars from Epirus in northwestern Greece and with the island of Corfu , which in antiquity was known as Corcyra. On
10769-581: The mechanism. The mechanism was retrieved from the wreckage in 1901, probably July. It is unknown how the mechanism came to be on the cargo ship. All of the items retrieved from the wreckage were transferred to the National Museum of Archaeology in Athens for storage and analysis. The mechanism appeared to be a lump of corroded bronze and wood; it went unnoticed for two years, while museum staff worked on piecing together more obvious treasures, such as
10890-597: The mid-1970s and is vested in the company that makes the software, not the employees or contractors who wrote it. The use of most software is governed by an agreement ( software license ) between the copyright holder and the user. Proprietary software is usually sold under a restrictive license that limits copying and reuse (often enforced with tools such as digital rights management (DRM)). Open-source licenses , in contrast, allow free use and redistribution of software with few conditions. Most open-source licenses used for software require that modifications be released under
11011-435: The month, but the day and time of day. The cycle is approximately 8 hours longer than an integer number of days. Translated into global spin, that means an eclipse occurs not only eight hours later, but one-third of a rotation farther to the west. Glyphs in 51 of the 223 synodic month cells of the dial specify the occurrence of 38 lunar and 27 solar eclipses. Some of the abbreviations in the glyphs read: The glyphs show whether
11132-404: The moon's elliptical orbit around the ecliptic in an 8.88 year cycle. The mean Sun position is, by definition, the current date. It is speculated that since significant effort was taken to ensure the position of the Moon was correct, there was likely to have also been a "true sun" pointer in addition to the mean Sun pointer, to track the elliptical anomaly of the Sun (the orbit of Earth around
11253-472: The operating system) can take this saved file and execute it as a process on the computer hardware. Some programming languages use an interpreter instead of a compiler. An interpreter converts the program into machine code at run time , which makes them 10 to 100 times slower than compiled programming languages. Software is often released with the knowledge that it is incomplete or contains bugs. Purchasers knowingly buy it in this state, which has led to
11374-408: The other end of the spiral before proceeding further. The front dial has two concentric circular scales. The inner scale marks the Greek signs of the zodiac, with division in degrees. The outer scale, which is a movable ring that sits flush with the surface and runs in a channel, is marked off with what appear to be days and has a series of corresponding holes beneath the ring in the channel. Since
11495-434: The other pieces that had been discovered. The German philologist Albert Rehm became interested in the device, and first proposed that it was an astronomical calculator. Investigations into the object lapsed until British science historian and Yale University professor Derek J. de Solla Price became interested in 1951. In 1971, Price and Greek nuclear physicist Charalampos Karakalos made X-ray and gamma-ray images of
11616-602: The per capita capacity of the world's general-purpose computers doubled every 18 months during the same two decades; the global telecommunication capacity per capita doubled every 34 months; the world's storage capacity per capita required roughly 40 months to double (every 3 years); and per capita broadcast information has doubled every 12.3 years. Massive amounts of data are stored worldwide every day, but unless it can be analyzed and presented effectively it essentially resides in what have been called data tombs: "data archives that are seldom visited". To address that issue,
11737-618: The physical world may also be part of the requirements for a software patent to be held valid. Software patents have been historically controversial . Before the 1998 case State Street Bank & Trust Co. v. Signature Financial Group, Inc. , software patents were generally not recognized in the United States. In that case, the Supreme Court decided that business processes could be patented. Patent applications are complex and costly, and lawsuits involving patents can drive up
11858-407: The position of the Moon, and a mean Sun pointer was shown, perhaps doubling as the current date pointer. The Moon position was not a simple mean Moon indicator which would indicate movement uniformly around a circular orbit; rather, it approximated the acceleration and deceleration of the Moon's elliptical orbit, through the earliest extant use of epicyclic gearing . It also tracked the precession of
11979-408: The release. Over time, the level of maintenance becomes increasingly restricted before being cut off entirely when the product is withdrawn from the market. As software ages , it becomes known as legacy software and can remain in use for decades, even if there is no one left who knows how to fix it. Over the lifetime of the product, software maintenance is estimated to comprise 75 percent or more of
12100-424: The same license, which can create complications when open-source software is reused in proprietary projects. Patents give an inventor an exclusive, time-limited license for a novel product or process. Ideas about what software could accomplish are not protected by law and concrete implementations are instead covered by copyright law . In some countries, a requirement for the claimed invention to have an effect on
12221-443: The scale backward one day every four years. If one is in favour of the 354 day evidence, the most likely interpretation is that the ring is a manifestation of a 354-day lunar calendar. Given the era of the mechanism's presumed construction and the presence of Egyptian month names, it is possibly the first example of the Egyptian civil-based lunar calendar proposed by Richard Anthony Parker in 1950. The lunar calendar's purpose
12342-553: The shipwreck, a date supported by Jones in 2017. Further dives were undertaken in 2014 and 2015, in the hope of discovering more of the mechanism. A five-year programme of investigations began in 2014 and ended in October 2019, with a new five-year session starting in May 2020. In 2022 researchers proposed the mechanism's initial calibration date, not construction date, could have been 23 December 178 BC. Other experts propose 204 BC as
12463-500: The shipwreck, which has been dated by multiple lines of evidence to approximately 70–60 BC. In 2022 researchers proposed its initial calibration date, not construction date, could have been 23 December 178 BC. Other experts propose 204 BC as a more likely calibration date. Machines with similar complexity did not appear again until the 14th century in western Europe. Captain Dimitrios Kontos ( Δημήτριος Κοντός ) and
12584-442: The start-up date of the Saros dial was shortly after the astronomical new moon of 28 April 205 BC. The Exeligmos dial is the secondary lower dial on the rear of the mechanism. The exeligmos cycle is a 54-year triple Saros cycle that is 19,756 days long. Since the length of the Saros cycle is to a third of a day (namely, 6,585 days plus 8 hours), a full exeligmos cycle returns the counting to an integral number of days, as reflected in
12705-406: The statues. Upon removal from seawater, the mechanism was not treated, resulting in deformational changes. On 17 May 1902, archaeologist Valerios Stais found one of the pieces of rock had a gear wheel embedded in it. He initially believed that it was an astronomical clock, but most scholars considered the device to be prochronistic , too complex to have been constructed during the same period as
12826-502: The storage and processing technologies employed, it is possible to distinguish four distinct phases of IT development: pre-mechanical (3000 BC — 1450 AD), mechanical (1450 — 1840), electromechanical (1840 — 1940), and electronic (1940 to present). Information technology is a branch of computer science , defined as the study of procedures, structures, and the processing of various types of data. As this field continues to evolve globally, its priority and importance have grown, leading to
12947-460: The surviving pieces of the outer ring: The other months have been reconstructed; some reconstructions of the mechanism omit the five days of the Egyptian intercalary month. The Zodiac dial contains Greek inscriptions of the members of the zodiac, which is believed to be adapted to the tropical month version rather than the sidereal : Also on the zodiac dial are single characters at specific points (see reconstruction at ref ). They are keyed to
13068-417: The system of regular (paper) mail, borrowing both terms (mail, letter, envelope, attachment, box, delivery, and others) and characteristic features — ease of use, message transmission delays, sufficient reliability and at the same time no guarantee of delivery. The advantages of e-mail are: easily perceived and remembered by a person addresses of the form user_name@domain_name (for example, somebody@example.com);
13189-431: The total development cost. Completing a software project involves various forms of expertise, not just in software programmers but also testing, documentation writing, project management , graphic design , user experience , user support, marketing , and fundraising. Software quality is defined as meeting the stated requirements as well as customer expectations. Quality is an overarching term that can refer to
13310-515: The upper left quarter of the Saros spiral and 14 inscriptions from said spiral. The fragment also contains inscriptions for the exeligmos dial and visible on the back surface the remnants of the dial face. Finally, this fragment contains some back door inscriptions. Many of the smaller fragments that have been found contain nothing of apparent value, but a few have inscriptions on them. Fragment 19 contains significant back door inscriptions including one reading "... 76 years ..." which refers to
13431-582: The wreck site in the 1970s date to the time of the device's construction, and posits that its origin may have been from the ancient Greek city of Pergamon , home of the Library of Pergamum . With its many scrolls of art and science, it was second in importance only to the Library of Alexandria during the Hellenistic period. The ship carrying the device contained vases in the Rhodian style, leading to
13552-558: The year of 1984, according to the National Westminster Bank Quarterly Review , the term information technology had been redefined as "The development of cable television was made possible by the convergence of telecommunications and computing technology (…generally known in Britain as information technology)." We then begin to see the appearance of the term in 1990 contained within documents for
13673-438: The year. The crank moves the date pointer about 78 days per full rotation, so hitting a particular day on the dial would be easily possible if the mechanism were in good working condition. The action of turning the hand crank would also cause all interlocked gears within the mechanism to rotate, resulting in the simultaneous calculation of the position of the Sun and Moon, the moon phase , eclipse , and calendar cycles, and perhaps
13794-502: Was able to handle the processing of more data. Scholarly articles began to be published from different organizations. Looking at early computing, Alan Turing , J. Presper Eckert , and John Mauchly were considered some of the major pioneers of computer technology in the mid-1900s. Giving them such credit for their developments, most of their efforts were focused on designing the first digital computer. Along with that, topics such as artificial intelligence began to be brought up as Turing
13915-493: Was beginning to question such technology of the time period. Devices have been used to aid computation for thousands of years, probably initially in the form of a tally stick . The Antikythera mechanism , dating from about the beginning of the first century BC, is generally considered the earliest known mechanical analog computer , and the earliest known geared mechanism. Comparable geared devices did not emerge in Europe until
14036-459: Was equivalent to 51 million households. Along with the Internet, new types of technology were also being introduced across the globe, which has improved efficiency and made things easier across the globe. Along with technology revolutionizing society, millions of processes could be done in seconds. Innovations in communication were also crucial as people began to rely on the computer to communicate through telephone lines and cable. The introduction of
14157-401: Was simultaneous with the compilers needed to translate them automatically into machine code. Most programs do not contain all the resources needed to run them and rely on external libraries . Part of the compiler's function is to link these files in such a way that the program can be executed by the hardware. Once compiled, the program can be saved as an object file and the loader (part of
14278-529: Was the Manchester Baby , which ran its first program on 21 June 1948. The development of transistors in the late 1940s at Bell Laboratories allowed a new generation of computers to be designed with greatly reduced power consumption. The first commercially available stored-program computer, the Ferranti Mark I , contained 4050 valves and had a power consumption of 25 kilowatts. By comparison,
14399-440: Was thought it may have been part of the Antikythera mechanism, as a " cog wheel ". There appears to be little evidence that it was part of the mechanism; it is more likely the disc was a bronze decoration on a piece of furniture. The Antikythera mechanism is generally referred to as the first known analogue computer. The quality and complexity of the mechanism's manufacture suggests it must have had undiscovered predecessors during
14520-416: Was to serve as a day-to-day indicator of successive lunations, and would also have assisted with the interpretation of the lunar phase pointer, and the Metonic and Saros dials. Undiscovered gearing, synchronous with the rest of the Metonic gearing of the mechanism, is implied to drive a pointer around this scale. Movement and registration of the ring relative to the underlying holes served to facilitate both
14641-447: Was volatile in the fact that it had to be continuously refreshed, and thus was lost once power was removed. The earliest form of non-volatile computer storage was the magnetic drum , invented in 1932 and used in the Ferranti Mark 1 , the world's first commercially available general-purpose electronic computer. IBM introduced the first hard disk drive in 1956, as a component of their 305 RAMAC computer system. Most digital data today
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