In computing, time-sharing is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking at the same time. Its introduction in the 1960s and emergence as the prominent model of computing in the 1970s represented a major technological shift in the history of computing. By allowing a large number of users to interact concurrently with a single computer, time-sharing lowered the cost of providing computing capability, made it possible for individuals and organizations to use a computer without owning one, promoted the interactive use of computers and the development of new interactive applications; the earliest computers were expensive devices, slow in comparison to models. Machines were dedicated to a particular set of tasks and operated by control panels, the operator manually entering small programs via switches in order to load and run a series of programs; these programs might take hours, or weeks, to run. As computers grew in speed, run times dropped, soon the time taken to start up the next program became a concern.
Batch processing methodologies evolved to decrease these "dead periods" by queuing up programs so that as soon as one program completed, the next would start. To support a batch processing operation, a number of comparatively inexpensive card punch or paper tape writers were used by programmers to write their programs "offline"; when typing was complete, the programs were submitted to the operations team, which scheduled them to be run. Important programs were started quickly; when the program run was completed, the output was returned to the programmer. The complete process might take days; the alternative of allowing the user to operate the computer directly was far too expensive to consider. This was; this situation limited interactive development to those organizations that could afford to waste computing cycles: large universities for the most part. Programmers at the universities decried the behaviors that batch processing imposed, to the point that Stanford students made a short film humorously critiquing it.
They experimented with new ways to interact directly with the computer, a field today known as human–computer interaction. Time-sharing was developed out of the realization that while any single user would make inefficient use of a computer, a large group of users together would not; this was due to the pattern of interaction: Typically an individual user entered bursts of information followed by long pauses but a group of users working at the same time would mean that the pauses of one user would be filled by the activity of the others. Given an optimal group size, the overall process could be efficient. Small slices of time spent waiting for disk, tape, or network input could be granted to other users; the concept is claimed to have been first described by John Backus in the 1954 summer session at MIT, by Bob Bemer in his 1957 article "How to consider a computer" in Automatic Control Magazine. In a paper published in December 1958 by W. F. Bauer, he wrote that "The computers would handle a number of problems concurrently.
Organizations would have input-output equipment installed on their own premises and would buy time on the computer much the same way that the average household buys power and water from utility companies." Implementing a system able to take advantage of this was difficult. Batch processing was a methodological development on top of the earliest systems. Since computers still ran single programs for single users at any time, the primary change with batch processing was the time delay between one program and the next. Developing a system that supported multiple users at the same time was a different concept; the "state" of each user and their programs would have to be kept in the machine, switched between quickly. This would take up computer cycles, on the slow machines of the era this was a concern. However, as computers improved in speed, in size of core memory in which users' states were retained, the overhead of time-sharing continually decreased speaking; the first project to implement time-sharing of user programs was initiated by John McCarthy at MIT in 1959 planned on a modified IBM 704, on an additionally modified IBM 709.
One of the deliverables of the project, known as the Compatible Time-Sharing System or CTSS, was demonstrated in November 1961. CTSS has a good claim to be the first time-sharing system and remained in use until 1973. Another contender for the first demonstrated time-sharing system was PLATO II, created by Donald Bitzer at a public demonstration at Robert Allerton Park near the University of Illinois in early 1961, but this was a special purpose system. Bitzer has long said that the PLATO project would have gotten the patent on time-sharing if only the University of Illinois had not lost the patent for 2 years. JOSS began time-sharing service in January 1964; the first commercially successful time-sharing system was the Dartmouth Time Sharing System. Throughout the late 1960s and the 1970s, computer terminals were multiplexed onto large institutional mainframe computers, which in many implementations sequentially polled the terminals to see whether any additional data was available or action was requested by the computer user.
Technology in interconnections were interrupt driven, some of these used parallel data trans
The Internet is the global system of interconnected computer networks that use the Internet protocol suite to link devices worldwide. It is a network of networks that consists of private, academic and government networks of local to global scope, linked by a broad array of electronic and optical networking technologies; the Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web, electronic mail and file sharing. Some publications no longer capitalize "internet"; the origins of the Internet date back to research commissioned by the federal government of the United States in the 1960s to build robust, fault-tolerant communication with computer networks. The primary precursor network, the ARPANET served as a backbone for interconnection of regional academic and military networks in the 1980s; the funding of the National Science Foundation Network as a new backbone in the 1980s, as well as private funding for other commercial extensions, led to worldwide participation in the development of new networking technologies, the merger of many networks.
The linking of commercial networks and enterprises by the early 1990s marked the beginning of the transition to the modern Internet, generated a sustained exponential growth as generations of institutional and mobile computers were connected to the network. Although the Internet was used by academia since the 1980s, commercialization incorporated its services and technologies into every aspect of modern life. Most traditional communication media, including telephony, television, paper mail and newspapers are reshaped, redefined, or bypassed by the Internet, giving birth to new services such as email, Internet telephony, Internet television, online music, digital newspapers, video streaming websites. Newspaper and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators; the Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, social networking. Online shopping has grown exponentially both for major retailers and small businesses and entrepreneurs, as it enables firms to extend their "brick and mortar" presence to serve a larger market or sell goods and services online.
Business-to-business and financial services on the Internet affect supply chains across entire industries. The Internet has no single centralized governance in either technological implementation or policies for access and usage; the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System, are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers. The technical underpinning and standardization of the core protocols is an activity of the Internet Engineering Task Force, a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. In November 2006, the Internet was included on USA Today's list of New Seven Wonders; when the term Internet is used to refer to the specific global system of interconnected Internet Protocol networks, the word is a proper noun that should be written with an initial capital letter.
In common use and the media, it is erroneously not capitalized, viz. the internet. Some guides specify that the word should be capitalized when used as a noun, but not capitalized when used as an adjective; the Internet is often referred to as the Net, as a short form of network. As early as 1849, the word internetted was used uncapitalized as an adjective, meaning interconnected or interwoven; the designers of early computer networks used internet both as a noun and as a verb in shorthand form of internetwork or internetworking, meaning interconnecting computer networks. The terms Internet and World Wide Web are used interchangeably in everyday speech. However, the World Wide Web or the Web is only one of a large number of Internet services; the Web is a collection of interconnected documents and other web resources, linked by hyperlinks and URLs. As another point of comparison, Hypertext Transfer Protocol, or HTTP, is the language used on the Web for information transfer, yet it is just one of many languages or protocols that can be used for communication on the Internet.
The term Interweb is a portmanteau of Internet and World Wide Web used sarcastically to parody a technically unsavvy user. Research into packet switching, one of the fundamental Internet technologies, started in the early 1960s in the work of Paul Baran and Donald Davies. Packet-switched networks such as the NPL network, ARPANET, the Merit Network, CYCLADES, Telenet were developed in the late 1960s and early 1970s; the ARPANET project led to the development of protocols for internetworking, by which multiple separate networks could be joined into a network of networks. ARPANET development began with two network nodes which were interconnected between the Network Measurement Center at the University of California, Los Angeles Henry Samueli School of Engineering and Applied Science directed by Leonard Kleinrock, the NLS system at SRI International by Douglas Engelbart in Menlo Park, California, on 29 October 1969; the third site was the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara, followed by the University of
First Cemetery of Athens
The First Cemetery of Athens is the official cemetery of the City of Athens and the first to be built. It soon became a prestigious cemetery for Greeks and foreigners; the cemetery is located behind the Temple of Olympian Zeus and the Panathinaiko Stadium in central Athens. It can be found at the top end of Anapafseos Street, it is a large green space with cypresses. In the cemetery there are three churches; the main one is the Church of Saint Theodores and there is a smaller one dedicated to Saint Lazarus. The third church of Saint Charles is a Catholic church; the cemetery includes several impressive tombs such as those of Heinrich Schliemann, designed by Ernst Ziller. There are burial areas for Protestants and Jews, this segregation is not compulsory; the cemetery is declared an historical monument. Odysseas Androutsos, hero of Greek War of Independence George Averoff, businessman Sotiria Bellou, singer Nikolaos Bourandas and fire service general, politician Yannoulis Chalepas, sculptor Christodoulos of Athens, Archbishop of Athens Richard Church, general Jules Dassin, actor Stratos Dionysiou, singer Odysseas Elytis, poet Demetrios Farmakopoulos, painter Adolf Furtwängler, archaeologist Dimitris Horn, actor Humphrey Jennings, filmmaker Georgios Kafantaris, prime minister Dimitrios Kallergis, statesman Tzeni Karezi, actress Manos Katrakis, actor Nikos Kavvadias, poet Stelios Kazantzidis, singer Theodoros Kolokotronis, politician Marika Kotopouli, actress Ellie Lambeti, actress Grigoris Lambrakis, politician Zoe Laskari, actress Vassilis Logothetidis, actor Yannis Makriyannis, military officer, author Orestis Makris, actor Alexandros Mavrokordatos, politician Melina Mercouri, politician Andreas Michalakopoulos, politician Dimitris Mitropanos, singer Dimitri Mitropoulos, pianist, composer Kostis Palamas, poet Alexandros Panagoulis, poet, democracy activist Antonios Papadakis, University of Athens' greatest benefactor Georgios Papadopoulos, military dictator during the Regime of the Colonels Andreas Papandreou, Prime Minister of Greece George Papandreou, Prime Minister of Greece Katina Paxinou, actress Alexandros Rizos Rangavis, poet Demis Roussos, singer Alekos Sakellarios, screenwriter, lyricist Rita Sakellariou, singer Alexandros Papanastasiou, lawyer Kalliroi Parren, feminist Heinrich Schliemann, amateur archaeologist who excavated the site of Troy Giorgos Seferis, poet Angelos Sikelianos, poet Michael Tositsas Charilaos Trikoupis, Prime Minister of Greece Vassilis Tsitsanis, rebetiko composer Ioannis Varvakis, member of Filiki Eteria Thanasis Veggos, actor Sofia Vembo, singer Aliki Vougiouklaki, actress T.
H. White, author Emmanuil Xanthos, a founder of the Filiki Eteria Nikos Xilouris and composer Nikos Zachariadis, General Secretary of the Communist Party of Greece from 1931 to 1956 Ernst Ziller, architect Xenophon Zolotas, prime minister Papyrus Larousse Britannica, 2006 Media related to First Cemetery of Athens at Wikimedia Commons
Boston is the capital and most populous city of the Commonwealth of Massachusetts in the United States. The city proper covers 48 square miles with an estimated population of 685,094 in 2017, making it the most populous city in New England. Boston is the seat of Suffolk County as well, although the county government was disbanded on July 1, 1999; the city is the economic and cultural anchor of a larger metropolitan area known as Greater Boston, a metropolitan statistical area home to a census-estimated 4.8 million people in 2016 and ranking as the tenth-largest such area in the country. As a combined statistical area, this wider commuting region is home to some 8.2 million people, making it the sixth-largest in the United States. Boston is one of the oldest cities in the United States, founded on the Shawmut Peninsula in 1630 by Puritan settlers from England, it was the scene of several key events of the American Revolution, such as the Boston Massacre, the Boston Tea Party, the Battle of Bunker Hill, the Siege of Boston.
Upon gaining U. S. independence from Great Britain, it continued to be an important port and manufacturing hub as well as a center for education and culture. The city has expanded beyond the original peninsula through land reclamation and municipal annexation, its rich history attracts many tourists, with Faneuil Hall alone drawing more than 20 million visitors per year. Boston's many firsts include the United States' first public park, first public or state school and first subway system; the Boston area's many colleges and universities make it an international center of higher education, including law, medicine and business, the city is considered to be a world leader in innovation and entrepreneurship, with nearly 2,000 startups. Boston's economic base includes finance and business services, information technology, government activities. Households in the city claim the highest average rate of philanthropy in the United States; the city has one of the highest costs of living in the United States as it has undergone gentrification, though it remains high on world livability rankings.
Boston's early European settlers had first called the area Trimountaine but renamed it Boston after Boston, England, the origin of several prominent colonists. The renaming on September 7, 1630, was by Puritan colonists from England who had moved over from Charlestown earlier that year in quest for fresh water, their settlement was limited to the Shawmut Peninsula, at that time surrounded by the Massachusetts Bay and Charles River and connected to the mainland by a narrow isthmus. The peninsula is thought to have been inhabited as early as 5000 BC. In 1629, the Massachusetts Bay Colony's first governor John Winthrop led the signing of the Cambridge Agreement, a key founding document of the city. Puritan ethics and their focus on education influenced its early history. Over the next 130 years, the city participated in four French and Indian Wars, until the British defeated the French and their Indian allies in North America. Boston was the largest town in British America until Philadelphia grew larger in the mid-18th century.
Boston's oceanfront location made it a lively port, the city engaged in shipping and fishing during its colonial days. However, Boston stagnated in the decades prior to the Revolution. By the mid-18th century, New York City and Philadelphia surpassed Boston in wealth. Boston encountered financial difficulties as other cities in New England grew rapidly. Many of the crucial events of the American Revolution occurred near Boston. Boston's penchant for mob action along with the colonists' growing distrust in Britain fostered a revolutionary spirit in the city; when the British government passed the Stamp Act in 1765, a Boston mob ravaged the homes of Andrew Oliver, the official tasked with enforcing the Act, Thomas Hutchinson the Lieutenant Governor of Massachusetts. The British sent two regiments to Boston in 1768 in an attempt to quell the angry colonists; this did not sit well with the colonists. In 1770, during the Boston Massacre, the army killed several people in response to a mob in Boston.
The colonists compelled the British to withdraw their troops. The event was publicized and fueled a revolutionary movement in America. In 1773, Britain passed the Tea Act. Many of the colonists saw the act as an attempt to force them to accept the taxes established by the Townshend Acts; the act prompted the Boston Tea Party, where a group of rebels threw an entire shipment of tea sent by the British East India Company into Boston Harbor. The Boston Tea Party was a key event leading up to the revolution, as the British government responded furiously with the Intolerable Acts, demanding compensation for the lost tea from the rebels; this led to the American Revolutionary War. The war began in the area surrounding Boston with the Battles of Concord. Boston itself was besieged for a year during the Siege of Boston, which began on April 19, 1775; the New England militia impeded the movement of the British Army. William Howe, 5th Viscount Howe the commander-in-chief of the British forces in North America, led the British army in the siege.
On June 17, the British captured the Charlestown peninsula in Boston, during the Battle of Bunker Hill. The British army outnumbered the militia stationed there, but it was a Py
A spreadsheet is an interactive computer application for organization and storage of data in tabular form. Spreadsheets developed as computerized analogs of paper accounting worksheets; the program operates on data entered in cells of a table. Each cell may contain either numeric or text data, or the results of formulas that automatically calculate and display a value based on the contents of other cells. A spreadsheet may refer to one such electronic document. Spreadsheet users can observe the effects on calculated values; this makes the spreadsheet useful for "what-if" analysis since many cases can be investigated without manual recalculation. Modern spreadsheet software can have multiple interacting sheets, can display data either as text and numerals, or in graphical form. Besides performing basic arithmetic and mathematical functions, modern spreadsheets provide built-in functions for common financial and statistical operations; such calculations as net present value or standard deviation can be applied to tabular data with a pre-programmed function in a formula.
Spreadsheet programs provide conditional expressions, functions to convert between text and numbers, functions that operate on strings of text. Spreadsheets have replaced paper-based systems throughout the business world. Although they were first developed for accounting or bookkeeping tasks, they now are used extensively in any context where tabular lists are built and shared. LANPAR, available in 1969, was the first electronic spreadsheet on mainframe and time sharing computers. LANPAR was an acronym: LANguage for Programming Arrays at Random. VisiCalc was the first electronic spreadsheet on a microcomputer, it helped turn the Apple II computer into a popular and used system. Lotus 1-2-3 was the leading spreadsheet. Excel now has the largest market share on the Macintosh platforms. A spreadsheet program is a standard feature of an office productivity suite. Web based spreadsheets are a new category. A spreadsheet consists of a table of cells arranged into rows and columns and referred to by the X and Y locations.
X locations, the columns, are represented by letters, "A", "B", "C", etc. while rows are represented by numbers, 1, 2, 3, etc. A single cell can be referred to by addressing its column, "C10" for instance; this electronic concept of cell references was first introduced in LANPAR and a variant used in VisiCalc, known as "A1 notation". Additionally, spreadsheets have the concept of a range, a group of cells contiguous. For instance, one can refer to the first ten cells in the first column with the range "A1:A10". LANPAR innovated forward referencing/natural order calculation which didn't re-appear until Lotus 123 and Microsoft's MultiPlan Version 2. In modern spreadsheet applications, several spreadsheets known as worksheets or sheets, are gathered together to form a workbook. A workbook is physically represented by a file, containing all the data for the book, the sheets and the cells with the sheets. Worksheets are represented by tabs that flip between pages, each one containing one of the sheets, although Numbers changes this model significantly.
Cells in a multi-sheet book add the sheet name to their reference, for instance, "Sheet 1! C10"; some systems extend this syntax to allow cell references to different workbooks. Users interact with sheets through the cells. A given cell can hold data by entering it in, or a formula, created by preceding the text with an equals sign. Data might include the string of text hello world, the number 5 or the date 16-Dec-91. A formula would begin with the equals sign, =5*3, but this would be invisible because the display shows the result of the calculation, 15 in this case, not the formula itself; this may lead to confusion in some cases. The key feature of spreadsheets is the ability for a formula to refer to the contents of other cells, which may in turn be the result of a formula. To make such a formula, one replaces a number with a cell reference. For instance, the formula =5*C10 would produce the result of multiplying the value in cell C10 by the number 5. If C10 holds the value 3 the result will be 15.
But C10 might hold its own formula referring to other cells, so on. The ability to chain formulas together is. Many problems can be broken down into a series of individual mathematical steps, these can be assigned to individual formulas in cells; some of these formulas can apply to ranges as well, like the SUM function that adds up all the numbers within a range. Spreadsheets share many principles and traits of databases, but spreadsheets and databases are not the same thing. A spreadsheet is just one table, whereas a database is a collection of many tables with machine-readable semantic relationships between them. While it is true that a workbook that contains three sheets is indeed a file containing multiple tables that can interact with each other, it lacks the relational structure of a database. Spreadsheets and databases are interoperable—sheets can be imported into databases to become tables within them, database queries can be exported into spreadsheets for further analysis. A spreadsheet program is one of the main components of an office productivity suite, which also contains a word processor, a presentation program, a database management system.
Programs within a suite use similar commands for similar functions. Sharing data between the components is easier tha
Système universitaire de documentation
The système universitaire de documentation or SUDOC is a system used by the libraries of French universities and higher education establishments to identify and manage the documents in their possession. The catalog, which contains more than 10 million references, allows students and researcher to search for bibliographical and location information in over 3,400 documentation centers, it is maintained by the Bibliographic Agency for Higher Education. Official website
The Advanced Research Projects Agency Network was an early packet-switching network and the first network to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet; the ARPANET was founded by the Advanced Research Projects Agency of the United States Department of Defense. The packet-switching methodology employed in the ARPANET was based on concepts and designs by Leonard Kleinrock, Paul Baran, Donald Davies, Lawrence Roberts; the TCP/IP communications protocols were developed for the ARPANET by computer scientists Robert Kahn and Vint Cerf, incorporated concepts from the French CYCLADES project directed by Louis Pouzin. As the project progressed, protocols for internetworking were developed by which multiple separate networks could be joined into a network of networks. Access to the ARPANET was expanded in 1981, when the National Science Foundation funded the Computer Science Network. In 1982, the Internet protocol suite was introduced as the standard networking protocol on the ARPANET.
In the early 1980s the NSF funded the establishment of national supercomputing centers at several universities and provided interconnectivity in 1986 with the NSFNET project, which created network access to the supercomputer sites in the United States from research and education organizations. The ARPANET was decommissioned in 1989. Voice and data communications were based on methods of circuit switching, as exemplified in the traditional telephone network, wherein each telephone call is allocated a dedicated, end to end, electronic connection between the two communicating stations; such stations might be computers. The temporarily dedicated line comprises many intermediary lines which are assembled into a chain that reaches from the originating station to the destination station. With packet switching, a network could share a single communication link for communication between multiple pairs of receivers and transmitters; the earliest ideas for a computer network intended to allow general communications among computer users were formulated by computer scientist J. C. R. Licklider of Bolt and Newman, in April 1963, in memoranda discussing the concept of the "Intergalactic Computer Network".
Those ideas encompassed many of the features of the contemporary Internet. In October 1963, Licklider was appointed head of the Behavioral Sciences and Command and Control programs at the Defense Department's Advanced Research Projects Agency, he convinced Ivan Sutherland and Bob Taylor that this network concept was important and merited development, although Licklider left ARPA before any contracts were assigned for development. Sutherland and Taylor continued their interest in creating the network, in part, to allow ARPA-sponsored researchers at various corporate and academic locales to utilize computers provided by ARPA, and, in part, to distribute new software and other computer science results. Taylor had three computer terminals in his office, each connected to separate computers, which ARPA was funding: one for the System Development Corporation Q-32 in Santa Monica, one for Project Genie at the University of California and another for Multics at the Massachusetts Institute of Technology.
Taylor recalls the circumstance: "For each of these three terminals, I had three different sets of user commands. So, if I was talking online with someone at S. D. C. and I wanted to talk to someone I knew at Berkeley, or M. I. T. about this, I had to get up from the S. D. C. Terminal, log into the other terminal and get in touch with them. I said, "Oh Man!", it's obvious what to do: If you have these three terminals, there ought to be one terminal that goes anywhere you want to go. That idea is the ARPANET". Meanwhile, since the early 1960s, Paul Baran at the RAND Corporation had been researching systems that could survive nuclear war and developed the idea of distributed adaptive message block switching. Donald Davies at the United Kingdom's National Physical Laboratory independently invented the same concept in 1965, his work, presented by a colleague caught the attention of ARPANET developers at a conference in Gatlinburg, Tennessee, in October 1967. He gave the first public demonstration, having coined the term packet switching, on 5 August 1968 and incorporated it into the NPL network in England.
Elizabeth Feinler created the first Resource Handbook for ARPANET in 1969 which led to the development of the ARPANET directory. The directory, built by Feinler and a team made it possible to navigate the ARPANET. Larry Roberts at ARPA applied Davies' concepts of packet switching for the ARPANET; the NPL network followed by the ARPANET were the first two networks in the world to use packet switching, were themselves connected together in 1973. Bob Taylor convinced ARPA's Director Charles M. Herzfeld to fund a network project in February 1966, Herzfeld transferred a million dollars from a ballistic missile defense program to Taylor's budget. Taylor hired Larry Roberts as a program manager in the ARPA Information Processing Techniques Office in January 1967 to work on the ARPANET. In April 1967, Roberts held a design session on technical standards; the initial standards for identification and authentication of users, transmission of characters, error checking and retransmission procedures were discussed.
At the meeting, Wesley Clark proposed minicomputers called Interface Message Processors should be used to interface to the network rather than the large mainframes that would be the nodes of the ARPANET. Roberts modified the ARPANET plan to incorporate Clark's suggestion; the plan was presented at the ACM Symposium in Gatlinburg, Tennessee, in October 1967. Donald Davies' work on packet switc