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The Oriental Orthodox Churches (also called "Old Oriental" churches) are those eastern churches that recognize the first three ecumenical councils—Nicaea, Constantinople, and Ephesus—but reject the dogmatic definitions of the Council of Chalcedon and instead espouse a Miaphysite christology.
The Oriental Orthodox communion consists of six groups: Syriac Orthodox, Coptic Orthodox, Ethiopian Orthodox, Eritrean Orthodox, Malankara Orthodox Syrian Church (India), and Armenian Apostolic churches. These six churches, while being in communion with each other, are completely independent hierarchically. These churches are generally not in communion with the Eastern Orthodox Church, with whom they are in dialogue for erecting a communion. Together, they have about 62 million members worldwide.
As some of the oldest religious institutions in the world, the Oriental Orthodox Churches have played a prominent role in the history and culture of Armenia, Egypt, Turkey, Eritrea, Ethiopia, Sudan, Iran, Azerbaijan and parts of the Middle East and India. An Eastern Christian body of autocephalous churches, its bishops are equal by virtue of episcopal ordination, and its doctrines can be summarized in that the churches recognize the validity of only the first three ecumenical councils.
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Some Oriental Orthodox Churches such as the Coptic Orthodox, Ethiopian Orthodox, Eritrean Orthodox, places a heavier emphasis on Old Testament teachings than one might find in other Christian denominations, and its followers adhere to certain practices: following dietary rules that are similar to Jewish Kashrut, require that their male members undergo circumcision, and observes ritual purification.
Church of the East.
The Church of the East, which was part of the Great Church, shared communion with those in the Roman Empire until the Council of Ephesus condemned Nestorius in 431. Continuing as a "dhimmi" community under the Rashidun Caliphate after the Muslim conquest of Persia (633–654), the Church of the East played a major role in the history of Christianity in Asia. Between the 9th and 14th centuries, it represented the world's largest Christian denomination in terms of geographical extent. It established dioceses and communities stretching from the Mediterranean Sea and today's Iraq and Iran, to India (the Saint Thomas Syrian Christians of Kerala), the Mongol kingdoms in Central Asia, and China during the Tang dynasty (7th–9th centuries). In the 13th and 14th centuries, the church experienced a final period of expansion under the Mongol Empire, where influential Church of the East clergy sat in the Mongol court.
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The Assyrian Church of the East, with an unbroken patriarchate established in the 17th century, is an independent Eastern Christian denomination which claims continuity from the Church of the East—in parallel to the Catholic patriarchate established in the 16th century that evolved into the Chaldean Catholic Church, an Eastern Catholic church in full communion with the Pope. It is an Eastern Christian church that follows the traditional christology and ecclesiology of the historical Church of the East. Largely aniconic and not in communion with any other church, it belongs to the eastern branch of Syriac Christianity, and uses the East Syriac Rite in its liturgy.
Its main spoken language is Syriac, a dialect of Eastern Aramaic, and the majority of its adherents are ethnic Assyrians, mostly living in Iran, Iraq, Syria, Turkey, India (Chaldean Syrian Church), and in the Assyrian diaspora. It is officially headquartered in the city of Erbil in northern Iraqi Kurdistan, and its original area also spreads into south-eastern Turkey and north-western Iran, corresponding to ancient Assyria. Its hierarchy is composed of metropolitan bishops and diocesan bishops, while lower clergy consists of priests and deacons, who serve in dioceses (eparchies) and parishes throughout the Middle East, India, North America, Oceania, and Europe (including the Caucasus and Russia).
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The Ancient Church of the East distinguished itself from the Assyrian Church of the East in 1964. It is one of the Assyrian churches that claim continuity with the historical Church of the East, one of the oldest Christian churches in Mesopotamia. It is officially headquartered in the city of Baghdad, Iraq. The majority of its adherents are ethnic Assyrians.
Protestantism.
In 1521, the Edict of Worms condemned Martin Luther and officially banned citizens of the Holy Roman Empire from defending or propagating his ideas. This split within the Roman Catholic church is now called the Reformation. Prominent Reformers included Martin Luther, Huldrych Zwingli, and John Calvin. The 1529 Protestation at Speyer against being excommunicated gave this party the name Protestantism. Luther's primary theological heirs are known as Lutherans. Zwingli and Calvin's heirs are far broader denominationally and are referred to as the Reformed tradition. The Anglican churches descended from the Church of England and organized in the Anglican Communion. Some Lutherans identify as Evangelical Catholics and some but not all Anglicans consider themselves both Protestant and Catholic. Protestants have developed their own culture, with major contributions in education, the humanities and sciences, the political and social order, the economy and the arts, and many other fields.
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Since the Anglican, Lutheran, and the Reformed branches of Protestantism originated for the most part in cooperation with the government, these movements are termed the "Magisterial Reformation". On the other hand, groups such as the Anabaptists, who often do not consider themselves to be Protestant, originated in the Radical Reformation, which though sometimes protected under "Acts of Toleration", do not trace their history back to any state church. They are further distinguished by their rejection of infant baptism; they believe in baptism only of adult believers—credobaptism (Anabaptists include the Amish, Apostolic, Bruderhof, Mennonites, Hutterites, River Brethren and Schwarzenau Brethren groups.)
The term "Protestant" also refers to any churches which formed later, with either the Magisterial or Radical traditions. In the 18th century, for example, Methodism grew out of Anglican minister John Wesley's evangelical revival movement. Several Pentecostal and non-denominational churches, which emphasize the cleansing power of the Holy Spirit, in turn grew out of Methodism. Because Methodists, Pentecostals and other evangelicals stress "accepting Jesus as your personal Lord and Savior", which comes from Wesley's emphasis of the New Birth, they often refer to themselves as being born-again.
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Protestantism is the second largest major group of Christians after Catholicism by number of followers, although the Eastern Orthodox Church is larger than any single Protestant denomination. Estimates vary, mainly over the question of which denominations to classify as Protestant. The total Protestant population has reached 1.17 billion in 2024, corresponding to nearly 44% of the world's Christians. The majority of Protestants are members of just a handful of denominational families, i.e. Adventism, Anabaptism (Amish, Apostolic, Bruderhof, Hutterites, Mennonites, River Brethren, and Schwarzenau Brethren), Anglicanism, Baptists, Lutheranism, Methodism, Moravianism/Hussites, Pentecostalism, Plymouth Brethren, Quakerism, Reformed Christianity (Congregationalists, Continental Reformed, Reformed Anglicans, and Presbyterians), and Waldensianism are the main families of Protestantism. Nondenominational, evangelical, charismatic, neo-charismatic, independent, and other churches are on the rise, and constitute a significant part of Protestant Christianity.
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Some groups of individuals who hold basic Protestant tenets identify themselves as "Christians" or "born-again Christians". They typically distance themselves from the confessionalism and creedalism of other Christian communities by calling themselves "non-denominational" or "evangelical". Often founded by individual pastors, they have little affiliation with historic denominations.
Restorationism.
The Second Great Awakening, a period of religious revival that occurred in the United States during the early 1800s, saw the development of a number of unrelated churches. They generally saw themselves as restoring the original church of Jesus Christ rather than reforming one of the existing churches. A common belief held by Restorationists was that the other divisions of Christianity had introduced doctrinal defects into Christianity, which was known as the Great Apostasy. In Asia, is a known Restorationist denomination that was established during the early 1900s. Other examples of Restorationist denominations include Irvingianism and Swedenborgianism.
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Some of the churches originating during this period are historically connected to early 19th-century camp meetings in the Midwest and upstate New York. One of the largest churches produced from the movement is the Church of Jesus Christ of Latter-day Saints. American Millennialism and Adventism, which arose from Evangelical Protestantism, influenced the Jehovah's Witnesses movement and, as a reaction specifically to William Miller, the Seventh-day Adventists. Others, including the Christian Church (Disciples of Christ), Evangelical Christian Church in Canada, Churches of Christ, and the Christian churches and churches of Christ, have their roots in the contemporaneous Stone-Campbell Restoration Movement, which was centered in Kentucky and Tennessee. Other groups originating in this time period include the Christadelphians and the previously mentioned Latter Day Saints movement. While the churches originating in the Second Great Awakening have some superficial similarities, their doctrine and practices vary significantly.
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Other.
Within Italy, Poland, Lithuania, Transylvania, Hungary, Romania, and the United Kingdom, Unitarian Churches emerged from the Reformed tradition in the 16th century; the Unitarian Church of Transylvania is an example of such a denomination that arose in this era. They adopted the Anabaptist doctrine of credobaptism.
Various smaller Independent Catholic communities, such as the Old Catholic Church, include the word "Catholic" in their title, and arguably have more or less liturgical practices in common with the Catholic Church but are no longer in full communion with the Holy See.
Spiritual Christians, such as the Doukhobors and Molokans, broke from the Russian Orthodox Church and maintain close association with Mennonites and Quakers due to similar religious practices; all of these groups are furthermore collectively considered to be peace churches due to their belief in pacifism.
Messianic Judaism (or the Messianic Movement) is the name of a Christian movement comprising a number of streams, whose members may consider themselves Jewish. The movement originated in the 1960s and 1970s, and it blends elements of religious Jewish practice with evangelical Christianity. Messianic Judaism affirms Christian creeds such as the messiahship and divinity of "Yeshua" (the Hebrew name of Jesus) and the Triune Nature of God, while also adhering to some Jewish dietary laws and customs.
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Esoteric Christians, such as The Christian Community, regard Christianity as a mystery religion and profess the existence and possession of certain esoteric doctrines or practices, hidden from the public and accessible only to a narrow circle of "enlightened", "initiated", or highly educated people.
Nondenominational Christianity or non-denominational Christianity consists of churches which typically distance themselves from the confessionalism or creedalism of other Christian communities by not formally aligning with a specific Christian denomination. Nondenominational Christianity first arose in the 18th century through the Stone-Campbell Restoration Movement, with followers organizing themselves as "Christians" and "Disciples of Christ", but many typically adhere to evangelical Christianity.
Cultural influence.
The history of the Christendom spans about 1,700 years and includes a variety of socio-political developments, as well as advances in the arts, architecture, literature, science, philosophy, and technology. Since the spread of Christianity from the Levant to Europe and North Africa during the early Roman Empire, Christendom has been divided in the pre-existing Greek East and Latin West. Consequently, different versions of the Christian cultures arose with their own rites and practices, centered around the cities of Rome (Western Christianity) and Carthage, whose communities were called Western or Latin Christendom, and Constantinople (Eastern Christianity), Antioch (Syriac Christianity), Kerala (Indian Christianity) and Alexandria (Coptic Christianity), whose communities were called Eastern or Oriental Christendom. The Byzantine Empire was one of the peaks in Christian history and Eastern Christian civilization. From the 11th to 13th centuries, Latin Christendom rose to the central role of the Western world.
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The Bible has had a profound influence on Western civilization and on cultures around the globe; it has contributed to the formation of Western law, art, texts, and education. With a literary tradition spanning two millennia, the Bible is one of the most influential works ever written. From practices of personal hygiene to philosophy and ethics, the Bible has directly and indirectly influenced politics and law, war and peace, sexual morals, marriage and family life, toilet etiquette, letters and learning, the arts, economics, social justice, medical care and more.
Christians have made a myriad of contributions to human progress in a broad and diverse range of fields, including philosophy, science and technology, medicine, fine arts and architecture, politics, literatures, music, and business. According to "100 Years of Nobel Prizes" a review of the Nobel Prizes award between 1901 and 2000 reveals that (65.4%) of Nobel Prizes Laureates, have identified Christianity in its various forms as their religious preference.
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Outside the Western world, Christianity has had an influence on various cultures, such as in Africa, the Near East, Middle East, East Asia, Southeast Asia, and the Indian subcontinent. Eastern Christian scientists and scholars of the medieval Islamic world (particularly Jacobite and Nestorian Christians) contributed to the Arab Islamic civilization during the reign of the Ummayyads and the Abbasids, by translating works of Greek philosophers to Syriac and afterwards, to Arabic. They also excelled in philosophy, science, theology, and medicine. Scholars and intellectuals agree Christians in the Middle East have made significant contributions to Arab and Islamic civilization since the introduction of Islam, and they have had a significant impact contributing the culture of the Mashriq, Turkey, and Iran.
Influence on Western culture.
Western culture, throughout most of its history, has been nearly equivalent to Christian culture, and a large portion of the population of the Western Hemisphere can be described as practicing or nominal Christians. The notion of "Europe" and the "Western World" has been intimately connected with the concept of "Christianity and Christendom". Many historians even attribute Christianity for being the link that created a unified European identity.
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Though Western culture contained several polytheistic religions during its early years under the Greek and Roman Empires, as the centralized Roman power waned, the dominance of the Catholic Church was the only consistent force in Western Europe. Until the Age of Enlightenment, Christian culture guided the course of philosophy, literature, art, music and science. Christian disciplines of the respective arts have subsequently developed into Christian philosophy, Christian art, Christian music, Christian literature, and so on.
Christianity has had a significant impact on education, as the church created the bases of the Western system of education, and was the sponsor of founding universities in the Western world, as the university is generally regarded as an institution that has its origin in the Medieval Christian setting. Historically, Christianity has often been a patron of science and medicine; many Catholic clergy, Jesuits in particular, have been active in the sciences throughout history and have made significant contributions to the development of science. Some scholars state that Christianity contributed to the rise of the Scientific Revolution. Protestantism also has had an important influence on science. According to the Merton Thesis, there was a positive correlation between the rise of English Puritanism and German Pietism on the one hand, and early experimental science on the other.
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The civilizing influence of Christianity includes social welfare, contribution to the medical and health care, founding hospitals, economics (as the Protestant work ethic), architecture, literature, personal hygiene (ablution), and family life. Historically, "extended families" were the basic family unit in the Christian culture and countries.
Cultural Christians are secular people with a Christian heritage who may not believe in the religious claims of Christianity, but who retain an affinity for the popular culture, art, music, and so on related to the religion.
"Postchristianity" is a term for the decline of Christianity, particularly in Europe, Canada, Australia, and to a minor degree the Southern Cone, in the 20th and 21st centuries, considered in terms of postmodernism. It refers to the loss of Christianity's monopoly on values and world view in historically Christian societies.
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Ecumenism.
Christian groups and denominations have long expressed ideals of being reconciled, and in the 20th century, Christian ecumenism advanced in two ways. One way was greater cooperation between groups, such as the World Evangelical Alliance founded in 1846 in London or the Edinburgh Missionary Conference of Protestants in 1910, the Justice, Peace and Creation Commission of the World Council of Churches founded in 1948 by Protestant and Orthodox churches, and similar national councils like the National Council of Churches in Australia, which includes Catholics.
The other way was an institutional union with united churches, a practice that can be traced back to unions between Lutherans and Calvinists in early 19th-century Germany. Congregationalist, Methodist, and Presbyterian churches united in 1925 to form the United Church of Canada, and in 1977 to form the Uniting Church in Australia. The Church of South India was formed in 1947 by the union of Anglican, Baptist, Methodist, Congregationalist, and Presbyterian churches.
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The Christian Flag is an ecumenical flag designed in the early 20th century to represent all of Christianity and Christendom.
The ecumenical, monastic Taizé Community is notable for being composed of more than one hundred brothers from Protestant and Catholic traditions. The community emphasizes the reconciliation of all denominations and its main church, located in Taizé, Saône-et-Loire, France, is named the "Church of Reconciliation". The community is internationally known, attracting over 100,000 young pilgrims annually.
Steps towards reconciliation on a global level were taken in 1965 by the Catholic and Orthodox churches, mutually revoking the excommunications that marked their Great Schism in 1054; the Anglican Catholic International Commission (ARCIC) working towards full communion between those churches since 1970; and some Lutheran and Catholic churches signing the Joint Declaration on the Doctrine of Justification in 1999 to address conflicts at the root of the Protestant Reformation. In 2006, the World Methodist Council, representing all Methodist denominations, adopted the declaration.
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Criticism, persecution, and apologetics.
Criticism.
Criticism of Christianity and Christians goes back to the Apostolic Age, with the New Testament recording friction between the followers of Jesus and the Pharisees and scribes (e.g., and ). In the 2nd century, Christianity was criticized by the Jews on various grounds, e.g., that the prophecies of the Hebrew Bible could not have been fulfilled by Jesus, given that he did not have a successful life. Additionally, a sacrifice to remove sins in advance, for everyone or as a human being, did not fit the Jewish sacrifice ritual; furthermore, God in Judaism is said to judge people on their deeds instead of their beliefs. One of the first comprehensive attacks on Christianity came from the Greek philosopher Celsus, who wrote "The True Word", a polemic criticizing Christians as being unprofitable members of society. In response, the church father Origen published his treatise "Contra Celsum", or "Against Celsus", a seminal work of Christian apologetics, which systematically addressed Celsus's criticisms and helped bring Christianity a level of academic respectability.
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By the 3rd century, criticism of Christianity had mounted. Wild rumors about Christians were widely circulated, claiming that they were atheists and that, as part of their rituals, they devoured human infants and engaged in incestuous orgies. The Neoplatonist philosopher Porphyry wrote the fifteen-volume "Adversus Christianos" as a comprehensive attack on Christianity, in part building on the teachings of Plotinus.
By the 12th century, the Mishneh Torah (i.e., Rabbi Moses Maimonides) was criticizing Christianity on the grounds of idol worship, in that Christians attributed divinity to Jesus, who had a physical body. In the 19th century, Nietzsche began to write a series of polemics on the "unnatural" teachings of Christianity (e.g. sexual abstinence), and continued his criticism of Christianity to the end of his life. In the 20th century, the philosopher Bertrand Russell expressed his criticism of Christianity in "Why I Am Not a Christian", formulating his rejection of Christianity.
Criticism of Christianity continues to date, e.g. Jewish and Muslim theologians criticize the doctrine of the Trinity held by most Christians, stating that this doctrine in effect assumes that there are three gods, running against the basic tenet of monotheism. New Testament scholar Robert M. Price has outlined the possibility that some Bible stories are based partly on myth in "The Christ Myth Theory and its problems".
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Persecution.
Christians are one of the most persecuted religious groups in the world, especially in the Middle-East, North Africa and South and East Asia. In 2017, Open Doors estimated approximately 260 million Christians are subjected annually to "high, very high, or extreme persecution" with North Korea considered the most hazardous nation for Christians. In 2019, a report commissioned by the United Kingdom's Secretary of State of the Foreign and Commonwealth Office (FCO) to investigate global persecution of Christians found persecution has increased, and is highest in the Middle East, North Africa, India, China, North Korea, and Latin America, among others, and that it is global and not limited to Islamic states. This investigation found that approximately 80% of persecuted believers worldwide are Christians.
Apologetics.
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Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering.
The term "computing" is also synonymous with counting and calculating. In earlier times, it was used in reference to the action performed by mechanical computing machines, and before that, to human computers.
History.
The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. Computing is intimately tied to the representation of numbers, though mathematical concepts necessary for computing existed before numeral systems. The earliest known tool for use in computation is the abacus, and it is thought to have been invented in Babylon circa between 2700 and 2300 BC. Abaci, of a more modern design, are still used as calculation tools today.
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The first recorded proposal for using digital electronics in computing was the 1931 paper "The Use of Thyratrons for High Speed Automatic Counting of Physical Phenomena" by C. E. Wynn-Williams. Claude Shannon's 1938 paper "A Symbolic Analysis of Relay and Switching Circuits" then introduced the idea of using electronics for Boolean algebraic operations.
The concept of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. John Bardeen and Walter Brattain, while working under William Shockley at Bell Labs, built the first working transistor, the point-contact transistor, in 1947. In 1953, the University of Manchester built the first transistorized computer, the Manchester Baby. However, early junction transistors were relatively bulky devices that were difficult to mass-produce, which limited them to a number of specialised applications.
In 1957, Frosch and Derick were able to manufacture the first silicon dioxide field effect transistors at Bell Labs, the first transistors in which drain and source were adjacent at the surface. Subsequently, a team demonstrated a working MOSFET at Bell Labs 1960. The MOSFET made it possible to build high-density integrated circuits, leading to what is known as the computer revolution or microcomputer revolution.
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Computer.
A computer is a machine that manipulates data according to a set of instructions called a computer program. The program has an executable form that the computer can use directly to execute the instructions. The same program in its human-readable source code form, enables a programmer to study and develop a sequence of steps known as an algorithm. Because the instructions can be carried out in different types of computers, a single set of source instructions converts to machine instructions according to the CPU type.
The execution process carries out the instructions in a computer program. Instructions express the computations performed by the computer. They trigger sequences of simple actions on the executing machine. Those actions produce effects according to the semantics of the instructions.
Computer hardware.
Computer hardware includes the physical parts of a computer, including the central processing unit, memory, and input/output. Computational logic and computer architecture are key topics in the field of computer hardware.
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Computer software.
Computer software, or just "software", is a collection of computer programs and related data, which provides instructions to a computer. Software refers to one or more computer programs and data held in the storage of the computer. It is a set of "programs, procedures, algorithms," as well as its "documentation" concerned with the operation of a data processing system. Program software performs the function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. The term was coined to contrast with the old term "hardware" (meaning physical devices). In contrast to hardware, software is intangible.
Software is also sometimes used in a more narrow sense, meaning application software only.
System software.
System software, or systems software, is computer software designed to operate and control computer hardware, and to provide a platform for running application software. System software includes operating systems, utility software, device drivers, window systems, and firmware. Frequently used development tools such as compilers, linkers, and debuggers are classified as system software. System software and middleware manage and integrate a computer's capabilities, but typically do not directly apply them in the performance of tasks that benefit the user, unlike application software.
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Application software.
Application software, also known as an "application" or an "app", is computer software designed to help the user perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software, and media players. Many application programs deal principally with documents. Apps may be bundled with the computer and its system software, or may be published separately. Some users are satisfied with the bundled apps and need never install additional applications. The system software manages the hardware and serves the application, which in turn serves the user.
Application software applies the power of a particular computing platform or system software to a particular purpose. Some apps, such as Microsoft Office, are developed in multiple versions for several different platforms; others have narrower requirements and are generally referred to by the platform they run on. For example, a "geography application for Windows" or an "Android application for education" or "Linux gaming". Applications that run only on one platform and increase the desirability of that platform due to the popularity of the application, known as killer applications.
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Computer network.
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow the sharing of resources and information. When at least one process in one device is able to send or receive data to or from at least one process residing in a remote device, the two devices are said to be in a network. Networks may be classified according to a wide variety of characteristics such as the medium used to transport the data, communications protocol used, scale, topology, and organizational scope.
Communications protocols define the rules and data formats for exchanging information in a computer network, and provide the basis for network programming. One well-known communications protocol is Ethernet, a hardware and link layer standard that is ubiquitous in local area networks. Another common protocol is the Internet Protocol Suite, which defines a set of protocols for internetworking, i.e. for data communication between multiple networks, host-to-host data transfer, and application-specific data transmission formats.
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Computer networking is sometimes considered a sub-discipline of electrical engineering, telecommunications, computer science, information technology, or computer engineering, since it relies upon the theoretical and practical application of these disciplines.
Internet.
The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users. This includes millions of private, public, academic, business, and government networks, ranging in scope from local to global. These networks are linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web and the infrastructure to support email.
Computer programming.
Computer programming is the process of writing, testing, debugging, and maintaining the source code and documentation of computer programs. This source code is written in a programming language, which is an artificial language that is often more restrictive than natural languages, but easily translated by the computer. Programming is used to invoke some desired behavior (customization) from the machine.
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Writing high-quality source code requires knowledge of both the computer science domain and the domain in which the application will be used. The highest-quality software is thus often developed by a team of domain experts, each a specialist in some area of development. However, the term "programmer" may apply to a range of program quality, from hacker to open source contributor to professional. It is also possible for a single programmer to do most or all of the computer programming needed to generate the proof of concept to launch a new killer application.
Computer programmer.
A programmer, computer programmer, or coder is a person who writes computer software. The term "computer programmer" can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst. A programmer's primary computer language (C, C++, Java, Lisp, Python, etc.) is often prefixed to the above titles, and those who work in a web environment often prefix their titles with "Web". The term "programmer" can be used to refer to a software developer, software engineer, computer scientist, or software analyst. However, members of these professions typically possess other software engineering skills, beyond programming.
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Computer industry.
The computer industry is made up of businesses involved in developing computer software, designing computer hardware and computer networking infrastructures, manufacturing computer components, and providing information technology services, including system administration and maintenance.
The software industry includes businesses engaged in development, maintenance, and publication of software. The industry also includes software services, such as training, documentation, and consulting.
Sub-disciplines of computing.
Computer engineering.
Computer engineering is a discipline that integrates several fields of electrical engineering and computer science required to develop computer hardware and software. Computer engineers usually have training in electronic engineering (or electrical engineering), software design, and hardware-software integration, rather than just software engineering or electronic engineering. Computer engineers are involved in many hardware and software aspects of computing, from the design of individual microprocessors, personal computers, and supercomputers, to circuit design. This field of engineering includes not only the design of hardware within its own domain, but also the interactions between hardware and the context in which it operates.
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Software engineering.
Software engineering is the application of a systematic, disciplined, and quantifiable approach to the design, development, operation, and maintenance of software, and the study of these approaches. That is, the application of engineering to software. It is the act of using insights to conceive, model and scale a solution to a problem. The first reference to the term is the 1968 NATO Software Engineering Conference, and was intended to provoke thought regarding the perceived "software crisis" at the time. Software development, a widely used and more generic term, does not necessarily subsume the engineering paradigm. The generally accepted concepts of Software Engineering as an engineering discipline have been specified in the Guide to the Software Engineering Body of Knowledge (SWEBOK). The SWEBOK has become an internationally accepted standard in ISO/IEC TR 19759:2015.
Computer science.
Computer science or computing science (abbreviated CS or Comp Sci) is the scientific and practical approach to computation and its applications. A computer scientist specializes in the theory of computation and the design of computational systems.
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Its subfields can be divided into practical techniques for its implementation and application in computer systems, and purely theoretical areas. Some, such as computational complexity theory, which studies fundamental properties of computational problems, are highly abstract, while others, such as computer graphics, emphasize real-world applications. Others focus on the challenges in implementing computations. For example, programming language theory studies approaches to the description of computations, while the study of computer programming investigates the use of programming languages and complex systems. The field of human–computer interaction focuses on the challenges in making computers and computations useful, usable, and universally accessible to humans.
Cybersecurity.
The field of cybersecurity pertains to the protection of computer systems and networks. This includes information and data privacy, preventing disruption of IT services and prevention of theft of and damage to hardware, software, and data.
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Data science.
Data science is a field that uses scientific and computing tools to extract information and insights from data, driven by the increasing volume and availability of data. Data mining, big data, statistics, machine learning and deep learning are all interwoven with data science.
Information systems.
Information systems (IS) is the study of complementary networks of hardware and software (see information technology) that people and organizations use to collect, filter, process, create, and distribute data. The ACM's "Computing Careers" describes IS as:
The study of IS bridges business and computer science, using the theoretical foundations of information and computation to study various business models and related algorithmic processes within a computer science discipline. The field of Computer Information Systems (CIS) studies computers and algorithmic processes, including their principles, their software and hardware designs, their applications, and their impact on society while IS emphasizes functionality over design.
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Information technology.
Information technology (IT) is the application of computers and telecommunications equipment to store, retrieve, transmit, and manipulate data, often in the context of a business or other enterprise. The term is commonly used as a synonym for computers and computer networks, but also encompasses other information distribution technologies such as television and telephones. Several industries are associated with information technology, including computer hardware, software, electronics, semiconductors, internet, telecom equipment, e-commerce, and computer services.
Research and emerging technologies.
DNA-based computing and quantum computing are areas of active research for both computing hardware and software, such as the development of quantum algorithms. Potential infrastructure for future technologies includes DNA origami on photolithography and quantum antennae for transferring information between ion traps. By 2011, researchers had entangled 14 qubits. Fast digital circuits, including those based on Josephson junctions and rapid single flux quantum technology, are becoming more nearly realizable with the discovery of nanoscale superconductors.
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Fiber-optic and photonic (optical) devices, which already have been used to transport data over long distances, are starting to be used by data centers, along with CPU and semiconductor memory components. This allows the separation of RAM from CPU by optical interconnects. IBM has created an integrated circuit with both electronic and optical information processing in one chip. This is denoted CMOS-integrated nanophotonics (CINP). One benefit of optical interconnects is that motherboards, which formerly required a certain kind of system on a chip (SoC), can now move formerly dedicated memory and network controllers off the motherboards, spreading the controllers out onto the rack. This allows standardization of backplane interconnects and motherboards for multiple types of SoCs, which allows more timely upgrades of CPUs.
Another field of research is spintronics. Spintronics can provide computing power and storage, without heat buildup. Some research is being done on hybrid chips, which combine photonics and spintronics. There is also research ongoing on combining plasmonics, photonics, and electronics.
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Cloud computing.
Cloud computing is a model that allows for the use of computing resources, such as servers or applications, without the need for interaction between the owner of these resources and the end user. It is typically offered as a service, making it an example of Software as a Service, Platforms as a Service, and Infrastructure as a Service, depending on the functionality offered. Key characteristics include on-demand access, broad network access, and the capability of rapid scaling. It allows individual users or small business to benefit from economies of scale.
One area of interest in this field is its potential to support energy efficiency. Allowing thousands of instances of computation to occur on one single machine instead of thousands of individual machines could help save energy. It could also ease the transition to renewable energy source, since it would suffice to power one server farm with renewable energy, rather than millions of homes and offices.
However, this centralized computing model poses several challenges, especially in security and privacy. Current legislation does not sufficiently protect users from companies mishandling their data on company servers. This suggests potential for further legislative regulations on cloud computing and tech companies.
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Quantum computing.
Quantum computing is an area of research that brings together the disciplines of computer science, information theory, and quantum physics. While the idea of information as part of physics is relatively new, there appears to be a strong tie between information theory and quantum mechanics. Whereas traditional computing operates on a binary system of ones and zeros, quantum computing uses qubits. Qubits are capable of being in a superposition, i.e. in both states of one and zero, simultaneously. Thus, the value of the qubit is not between 1 and 0, but changes depending on when it is measured. This trait of qubits is known as quantum entanglement, and is the core idea of quantum computing that allows quantum computers to do large scale computations. Quantum computing is often used for scientific research in cases where traditional computers do not have the computing power to do the necessary calculations, such in molecular modeling. Large molecules and their reactions are far too complex for traditional computers to calculate, but the computational power of quantum computers could provide a tool to perform such calculations. |
Casino
A casino is a facility for gambling. Casinos are often built near or combined with hotels, resorts, restaurants, retail shops, cruise ships, and other tourist attractions. Some casinos also host live entertainment, such as stand-up comedy, concerts, and sports.
and usage.
"Casino" is of Italian origin; the root means a house. The term "casino" may mean a small country villa, summerhouse, or social club. During the 19th century, "casino" came to include other public buildings where pleasurable activities took place; such edifices were usually built on the grounds of a larger Italian villa or palazzo, and were used to host civic town functions, including dancing, gambling, music listening, and sports. Examples in Italy include Villa Farnese and Villa Giulia, and in the US the Newport Casino in Newport, Rhode Island. In modern-day Italian, a is a brothel (also called , literally "closed house"), a mess (confusing situation), or a noisy environment; a gaming house is spelt , with an accent.
Not all casinos are used for gaming. The Catalina Casino, on Santa Catalina Island, California, has never been used for traditional games of chance, which were already outlawed in California by the time it was built. The Copenhagen Casino was a Danish theatre which also held public meetings during the 1848 Revolution, which made Denmark a constitutional monarchy.
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In military and non-military usage, a (Spanish) or (German) is an officers' mess.
History of gambling houses.
The precise origin of gambling is unknown. It is generally believed that gambling in some form or another has been seen in almost every society in history. From Ancient Mesopotamia, Greeks and Romans to Napoleon's France and Elizabethan England, much of history is filled with stories of entertainment based on games of chance.
The first known European gambling house, not called a casino although meeting the modern definition, was the Ridotto, established in Venice, Italy, in 1638 by the Great Council of Venice to provide controlled gambling during the carnival season. It was closed in 1774 as the city government felt it was impoverishing the local gentry.
In American history, early gambling establishments were known as saloons. The creation and importance of saloons was greatly influenced by four major cities: New Orleans, St. Louis, Chicago and San Francisco. It was in the saloons that travelers could find people to talk to, drink with, and often gamble with. During the early 20th century in the US, gambling was outlawed by state legislation. However, in 1931, gambling was legalized throughout the state of Nevada, where the US's first legalized casinos were set up. In 1976 New Jersey allowed gambling in Atlantic City, now the US's second largest gambling city.
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Gambling in casinos.
Most jurisdictions worldwide have a minimum gambling age of 18 to 21.
Customers gamble by playing games of chance, in some cases with an element of skill, such as craps, roulette, baccarat, blackjack, and video poker. Most games have mathematically determined odds that ensure the house has at all times an advantage over the players. This can be expressed more precisely by the notion of expected value, which is uniformly negative (from the player's perspective). This advantage is called the "house edge". In games such as poker where players play against each other, the house takes a commission called the rake. Casinos sometimes give out complimentary items or comps to gamblers.
"Payout" is the percentage of funds ("winnings") returned to players. Video lottery machines (slot machines) have become one of the most popular forms of gambling in casinos. investigative reports have started calling into question whether the modern-day slot-machine is addictive.
Design.
Factors influencing gambling tendencies include sound, odour and lighting. Natasha Dow Schüll, an anthropologist at the Massachusetts Institute of Technology, highlights the decision of the audio directors at Silicon Gaming to make its slot machines resonate in "the universally pleasant tone of C, sampling existing casino soundscapes to create a sound that would please but not clash".
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Alan Hirsch, founder of the Smell & Taste Treatment and Research Foundation in Chicago, studied the impact of certain scents on gamblers, discerning that a pleasant albeit unidentifiable odor released by Las Vegas slot machines generated about 50% more in daily revenue. He suggested that the scent acted as an aphrodisiac, causing a more aggressive form of gambling.
Markets.
The following lists major casino markets in the world with casino revenue of over US$1 billion as published in PricewaterhouseCoopers's report on
the outlook for the global casino market:
By company.
According to Bloomberg, accumulated revenue of the biggest casino operator companies worldwide amounted to almost US$55 billion in 2011. SJM Holdings Ltd. was the leading company in this field, earning $9.7 bn in 2011, followed by Las Vegas Sands Corp. at $7.4 bn. The third-biggest casino operator company (based on revenue) was Caesars Entertainment, with revenue of US$6.2 bn.
Significant sites.
While there are casinos in many places, a few places have become well known specifically for gambling. Perhaps the place almost defined by its casino is Monte Carlo, but other places are known as gambling centers.
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Monte Carlo, Monaco.
Opened in 1865, Monte Carlo Casino, located in Monte Carlo city, in Monaco, is a casino and a tourist attraction.
Monte Carlo Casino has been depicted in books, songs and films. It features prominently in the James Bond films "Never Say Never Again" (1983) and "GoldenEye" (1995). Casinos feature throughout the Bond series, with the character introducing himself to the world at Les Ambassadeurs Club in Mayfair, London with the line "Bond, James Bond" in "Dr. No" (1962).
The Monte Carlo Casino is mentioned in the 1891 British music hall song "The Man Who Broke the Bank at Monte Carlo" as well as the 1935 film of the same name. The song was inspired by the exploits of English trickster Charles Wells, who in 1891 "broke the bank" on many occasions on the first two of his three trips to the casino.
The Monte Carlo Casino features in Ben Mezrich's 2005 book "Busting Vegas", where a group of students beat the casino out of nearly $1 million. This book is based on real people and events; however, many of those events are contested by main character Semyon Dukach.
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Campione d'Italia.
Casinò di Campione is located in the tiny Italian enclave of Campione d'Italia, within Ticino, Switzerland. The casino was founded in 1917 as a site to gather information from foreign diplomats during the First World War. Today it is owned by the Italian government, and operated by the municipality. With gambling laws being less strict than in Italy and Switzerland, it is among the most popular gambling destination besides Monte Carlo. The income from the casino is sufficient for the operation of Campione without the imposition of taxes, or obtaining of other revenue. In 2007, the casino moved into new premises of more than , making it the largest casino in Europe. The new casino was built alongside the old one, which dated from 1933 and has since been demolished.
Malta.
The archipelago of Malta is a particularly famous place for casinos, standing out mainly with the historic casino located at the princely residence of Dragonara. Dragonara Palace was built in 1870. Its name comes from the Dragonara Point, the peninsula where it is built. On 15 July 1964, the palace opened as a casino.
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Macau.
The former Portuguese colony of Macau, a special administrative region of the People's Republic of China since 1999, is a popular destination for visitors who wish to gamble. This started in Portuguese times, when Macau was popular with visitors from nearby Hong Kong, where gambling was more closely regulated. The Venetian Macao is currently the largest casino in the world. Macau also surpassed Las Vegas as the largest gambling market in the world.
Germany.
Machine-based gaming is only permitted in land-based casinos, restaurants, bars and gaming halls, and only subject to a licence. Online slots are, at the moment, only permitted if they are operated under a Schleswig-Holstein licence. AWPs are governed by federal law – the Trade Regulation Act and the Gaming Ordinance.
Portugal.
The Casino Estoril, located in the municipality of Cascais, on the Portuguese Riviera, near Lisbon, is the largest casino in Europe by capacity.
During the World War II, it was reputed to be a gathering point for spies, dispossessed royals, and wartime adventurers; it became an inspiration for Ian Fleming's James Bond 007 novel "Casino Royale".
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Russia.
There are four legal gaming zones in Russia: "Siberian Coin" (Altay), "Yantarnaya" (Kaliningrad region), "Azov-city" (Rostov region) and "Primorie" (Primorie region).
Singapore.
Singapore is an up-and-coming destination for visitors wanting to gamble, although there are currently only two casinos (both foreign owned), in Singapore. The Marina Bay Sands is the second most expensive standalone casino in the world, at a price of US$6.8 billion, and is among the world's ten most expensive buildings.
United States.
With currently over 1,000 casinos, the United States has the largest number of casinos in the world. The number continues to grow steadily as more states seek to legalize casinos. 40 states now have some form of casino gambling. Interstate competition, such as gaining tourism, has been a driving factor to continuous legalization. Relatively small places such as Las Vegas are best known for gambling; larger cities such as Chicago are not defined by their casinos in spite of the large turnover.
The Las Vegas Valley has the largest concentration of casinos in the United States. Based on revenue, Atlantic City, New Jersey, ranks second, and the Chicago region third.
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Top American casino markets by revenue (2022 annual revenues):
The Nevada Gaming Control Board divides Clark County, which is coextensive with the Las Vegas metropolitan area, into seven market regions for reporting purposes.
Native American gaming has been responsible for a rise in the number of casinos outside of Las Vegas and Atlantic City.
Vietnam.
In Vietnam, the term "casinos" encompasses gambling activities within the country. Unofficially defined, a "casino" typically denotes a well-established and professional gambling establishment that is generally lawful but exclusively caters to foreign players. On the other hand, "gambling houses" or "gambling dens" are smaller, illicit gambling venues.
As of 2022, Vietnam has 9 operating casinos, including: Đồ Sơn casino (Hải Phòng), Lợi Lai casino, Hoàng Gia casino (Quảng Ninh), Hồng Vận casino (Quảng Ninh), Lào Cai casino (Lào Cai), Silver Shores casino (Đà Nẵng), Hồ Tràm casino (Bà Rịa – Vũng Tàu), Nam Hội An casino (Quảng Nam), Phú Quốc casino in Kien Giang.
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In a survey conducted by the Vietnamese Institute for Sustainable Regional Development and released on September 30, 2015, it was found that 71% of the respondents held the belief that allowing Vietnamese individuals to access casinos would result in an increase in the number of players. Furthermore, 47.4% of the participants expressed the view that engaging in rewarding recreational activities has a positive impact on job opportunities for residents. Additionally, 46.2% of the respondents believed that such activities contribute positively to Vietnam's ability to attract investments.
Security.
Given the large amounts of currency handled within a casino, both patrons and staff may be tempted to cheat and steal, in collusion or independently; most casinos have security measures to prevent this. Security cameras located throughout the casino are the most basic measure.
Modern casino security is usually divided between a physical security force and a specialized surveillance department. The physical security force usually patrols the casino and responds to calls for assistance and reports of suspicious or definite criminal activity. A specialized surveillance department operates the casino's closed-circuit-television system, known in the industry as the eye in the sky. Both of these specialized casino security departments work very closely with each other to ensure the safety of both guests and the casino's assets, and have been quite successful in preventing crime. Some casinos also have catwalks in the ceiling above the casino floor, which allow surveillance personnel to look directly down, through one way glass, on the activities at the tables and slot machines.
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When it opened in 1989, The Mirage was the first casino to use cameras full-time on all table games.
In addition to cameras and other technological measures, casinos also enforce security through rules of conduct and behavior; for example, players at card games are required to keep the cards they are holding in their hands visible at all times.
Business practices.
Over the past few decades, casinos have developed many different marketing techniques for attracting and maintaining loyal patrons. Many casinos use a loyalty rewards program used to track players' spending habits and target their patrons more effectively, by sending mailings with free slot play and other promotions. Casino Helsinki in Helsinki, Finland, for example, donates all of its profits to charity.
Crime.
Casinos have been linked to organised crime, with early casinos in Las Vegas originally dominated by the American Mafia and in Macau by Triad syndicates.
According to some police reports, local incidence of reported crime often doubles or triples within three years of a casino's opening. In a 2004 report by the US Department of Justice, researchers interviewed people who had been arrested in Las Vegas and Des Moines and found that the percentage of problem or pathological gamblers among the arrestees was three to five times higher than in the general population.
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It has been said that economic studies showing a positive relationship between casinos and crime usually fail to consider the visiting population: they count crimes committed by visitors but do not count visitors in the population measure, which overstates the crime rate. Part of the reason this methodology is used, despite the overstatement, is that reliable data on tourist count are often not available.
Occupational health and safety.
Casinos are subject to specific regulations for worker safety, as casino employees are both at greater risk for cancers resulting from exposure to second-hand tobacco smoke and musculoskeletal injuries from repetitive motions while running table games over many hours. These are not the extent of the hazards casino workers may be exposed to, but every location is different. Most casinos do not meet the requirements for certain protective measures, such as protection against airborne metal dusts from coins or hearing protection against high noise levels, though these measures are still implemented when evaluated and determined necessary. |
Khmer language
Khmer ( ; , UNGEGN: ) is an Austroasiatic language spoken natively by the Khmer people. This language is an official language and national language of Cambodia. The language is also widely spoken by Khmer people in Eastern Thailand and Isan, Thailand, also in Southeast and Mekong Delta of Vietnam.
Khmer has been influenced considerably by Sanskrit and Pali especially in the royal and religious registers, through Hinduism and Buddhism, due to Old Khmer being the language of the historical empires of Chenla and Angkor.
The vast majority of Khmer speakers speak "Central Khmer", the dialect of the central plain where the Khmer are most heavily concentrated. Within Cambodia, regional accents exist in remote areas but these are regarded as varieties of Central Khmer. Two exceptions are the speech of the capital, Phnom Penh, and that of the Khmer Khe in Stung Treng province, both of which differ sufficiently enough from Central Khmer to be considered separate dialects of Khmer.
Outside of Cambodia, three distinct dialects are spoken by ethnic Khmers native to areas that were historically part of the Khmer Empire. The Northern Khmer dialect is spoken by over a million Khmers in the southern regions of Northeast Thailand and is treated by some linguists as a separate language. Khmer Krom, or Southern Khmer, is the first language of the Khmer of Vietnam, while the Khmer living in the remote Cardamom Mountains speak a very conservative dialect that still displays features of the Middle Khmer language.
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Khmer is primarily an analytic, isolating language. There are no inflections, conjugations or case endings. Instead, particles and auxiliary words are used to indicate grammatical relationships. General word order is subject–verb–object, and modifiers follow the word they modify. Classifiers appear after numbers when used to count nouns, though not always so consistently as in languages like Chinese. In spoken Khmer, topic-comment structure is common, and the perceived social relation between participants determines which sets of vocabulary, such as pronouns and honorifics, are proper.
Khmer differs from neighboring languages such as Burmese, Thai, Lao, and Vietnamese in that it is not a tonal language. Words are stressed on the final syllable, hence many words conform to the typical Mon–Khmer pattern of a stressed syllable preceded by a minor syllable. The language has been written in the Khmer script, an abugida descended from the Brahmi script via the southern Indian Pallava script, since at least the 7th century. The script's form and use has evolved over the centuries; its modern features include subscripted versions of consonants used to write clusters and a division of consonants into two series with different inherent vowels.
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Classification.
Khmer is a member of the Austroasiatic language family, the autochthonous family in an area that stretches from the Malay Peninsula through Southeast Asia to East India. Austroasiatic, which also includes Mon, Vietnamese and Munda, has been studied since 1856 and was first proposed as a language family in 1907. Despite the amount of research, there is still doubt about the internal relationship of the languages of Austroasiatic.
Diffloth places Khmer in an eastern branch of the Mon-Khmer languages. In these classification schemes Khmer's closest genetic relatives are the Bahnaric and Pearic languages. More recent classifications doubt the validity of the Mon-Khmer sub-grouping and place the Khmer language as its own branch of Austroasiatic equidistant from the other 12 branches of the family.
Geographic distribution and dialects.
Khmer is spoken by some 13 million people in Cambodia, where it is the official language. It is also a second language for most of the minority groups and indigenous hill tribes there. Additionally there are a million speakers of Khmer native to southern Vietnam (1999 census) and 1.4 million in northeast Thailand (2006).
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Khmer dialects, although mutually intelligible, are sometimes quite marked. Notable variations are found in speakers from Phnom Penh (Cambodia's capital city), the rural Battambang area, the areas of Northeast Thailand adjacent to Cambodia such as Surin province, the Cardamom Mountains, and southern Vietnam. The dialects form a continuum running roughly north to south. Standard Cambodian Khmer is mutually intelligible with the others but a Khmer Krom speaker from Vietnam, for instance, may have great difficulty communicating with a Khmer native of Sisaket Province in Thailand.
The following is a classification scheme showing the development of the modern Khmer dialects.
Standard Khmer, or Central Khmer, the language as taught in Cambodian schools and used by the media, is based on the dialect spoken throughout the Central Plain, a region encompassed by the northwest and central provinces.
Northern Khmer (called in Khmer) refers to the dialects spoken by many in several border provinces of present-day northeast Thailand. After the fall of the Khmer Empire in the early 15th century, the Dongrek Mountains served as a natural border leaving the Khmer north of the mountains under the sphere of influence of the Kingdom of Lan Xang. The conquests of Cambodia by Naresuan the Great for Ayutthaya furthered their political and economic isolation from Cambodia proper, leading to a dialect that developed relatively independently from the midpoint of the Middle Khmer period.
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This has resulted in a distinct accent influenced by the surrounding tonal languages Lao and Thai, lexical differences, and phonemic differences in both vowels and distribution of consonants. Syllable-final , which has become silent in other dialects of Khmer, is still pronounced in Northern Khmer. Some linguists classify Northern Khmer as a separate but closely related language rather than a dialect.
Western Khmer, also called Cardamom Khmer or Chanthaburi Khmer, is spoken by a very small, isolated population in the Cardamom mountain range extending from western Cambodia into eastern Central Thailand. Although little studied, this variety is unique in that it maintains a definite system of vocal register that has all but disappeared in other dialects of modern Khmer.
Phnom Penh Khmer is spoken in the capital and surrounding areas. This dialect is characterized by merging or complete elision of syllables, which speakers from other regions consider a "relaxed" pronunciation. For instance, "Phnom Penh" is sometimes shortened to "m'Penh". Another characteristic of Phnom Penh speech is observed in words with an "r" either as an initial consonant or as the second member of a consonant cluster (as in the English word "bread"). The "r", trilled or flapped in other dialects, is either pronounced as a uvular trill or not pronounced at all.
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This alters the quality of any preceding consonant, causing a harder, more emphasized pronunciation. Another unique result is that the syllable is spoken with a low-rising or "dipping" tone much like the "hỏi" tone in Vietnamese. For example, some people pronounce ('fish') as : the is dropped and the vowel begins by dipping much lower in tone than standard speech and then rises, effectively doubling its length. Another example is the word ('study'), which is pronounced , with the uvular "r" and the same intonation described above.
Khmer Krom or Southern Khmer is spoken by the indigenous Khmer population of the Mekong Delta, formerly controlled by the Khmer Empire but part of Vietnam since 1698. Khmers are persecuted by the Vietnamese government for using their native language and, since the 1950s, have been forced to take Vietnamese names. Consequently, very little research has been published regarding this dialect. It has been generally influenced by Vietnamese for three centuries and accordingly displays a pronounced accent, tendency toward monosyllabic words and lexical differences from Standard Khmer.
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Khmer Khe is spoken in the Se San, Srepok and Sekong river valleys of Sesan and Siem Pang districts in Stung Treng Province. Following the decline of Angkor, the Khmer abandoned their northern territories, which the Lao then settled. In the 17th century, Chey Chetha XI led a Khmer force into Stung Treng to retake the area. The Khmer Khe living in this area of Stung Treng in modern times are presumed to be the descendants of this group. Their dialect is thought to resemble that of pre-modern Siem Reap.
Historical periods.
Linguistic study of the Khmer language divides its history into four periods, one of which, the Old Khmer period, is subdivided into pre-Angkorian and Angkorian. Pre-Angkorian Khmer is the Old Khmer language from 600 through 800 CE. Angkorian Khmer is the language as it was spoken in the Khmer Empire from the 9th century until the 13th century.
The following centuries saw changes in morphology, phonology and lexicon. The language of this transition period, from about the 14th to 18th centuries, is referred to as Middle Khmer and saw borrowings from Thai in the literary register. Modern Khmer is dated from the 19th century to today.
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The following table shows the conventionally accepted historical stages of Khmer.
Just as modern Khmer was emerging from the transitional period represented by Middle Khmer, Cambodia fell under the influence of French colonialism. Thailand, which had for centuries claimed suzerainty over Cambodia and controlled succession to the Cambodian throne, began losing its influence on the language. In 1887 Cambodia was fully integrated into French Indochina, which brought in a French-speaking aristocracy. This led to French becoming the language of higher education and the intellectual class. By 1907, the French had wrested over half of modern-day Cambodia, including the north and northwest where Thai had been the prestige language, back from Thai control and reintegrated it into the country.
Many native scholars in the early 20th century, led by a monk named Chuon Nath, resisted the French and Thai influences on their language. Forming the government sponsored Cultural Committee to define and standardize the modern language, they championed Khmerization, purging of foreign elements, reviving affixation, and the use of Old Khmer roots and historical Pali and Sanskrit to coin new words for modern ideas. Opponents, led by Keng Vannsak, who embraced "total Khmerization" by denouncing the reversion to classical languages and favoring the use of contemporary colloquial Khmer for neologisms, and Ieu Koeus, who favored borrowing from Thai, were also influential.
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Koeus later joined the Cultural Committee and supported Nath. Nath's views and prolific work won out and he is credited with cultivating modern Khmer-language identity and culture, overseeing the translation of the entire Pali Buddhist canon into Khmer. He also created the modern Khmer language dictionary that is still in use today, helping preserve Khmer during the French colonial period.
Phonology.
The phonological system described here is the inventory of sounds of the standard spoken language, represented using the International Phonetic Alphabet (IPA).
Consonants.
The voiceless plosives may occur with or without aspiration (as vs. , etc.); this difference is contrastive before a vowel. However, the aspirated sounds in that position may be analyzed as sequences of two phonemes: . This analysis is supported by the fact that infixes can be inserted between the stop and the aspiration; for example ('big') becomes ('size') with a nominalizing infix. When one of these plosives occurs initially before another consonant, aspiration is no longer contrastive and can be regarded as mere phonetic detail: slight aspiration is expected when the following consonant is not one of (or if the initial plosive is ).
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The voiced plosives are pronounced as implosives by most speakers, but this feature is weak in educated speech, where they become .
In syllable-final position, and approach and respectively. The stops are unaspirated and have no audible release when occurring as syllable finals.
In addition, the consonants , , and occur occasionally in recent loan words in the speech of Cambodians familiar with French and other languages.
Vowels.
Various authors have proposed slightly different analyses of the Khmer vowel system. This may be in part because of the wide degree of variation in pronunciation between individual speakers, even within a dialectal region. The description below follows Huffman (1970). The number of vowel nuclei and their values vary between dialects; differences exist even between the Standard Khmer system and that of the Battambang dialect on which the standard is based.
In addition, some diphthongs and triphthongs are analyzed as a vowel nucleus plus a semivowel ( or ) coda because they cannot be followed by a final consonant. These include: (with short monophthongs) , , , , ; (with long monophthongs) , ; (with long diphthongs) , , , , and .
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The independent vowels are the vowels that can exist without a preceding or trailing consonant. The independent vowels may be used as monosyllabic words, or as the initial syllables in longer words. Khmer words never begin with regular vowels; they can, however, begin with independent vowels. Example: ឰដ៏, ឧទាហរណ៍, ឧត្តម, ឱកាស...។
Syllable structure.
A Khmer syllable begins with a single consonant, or else with a cluster of two, or rarely three, consonants. The only possible clusters of three consonants at the start of a syllable are , and (with aspirated consonants analyzed as two-consonant sequences) . There are 85 possible two-consonant clusters (including [pʰ] etc. analyzed as etc.). All the clusters are shown in the following table, phonetically, i.e. superscript can mark either contrastive or non-contrastive aspiration (see above).
Slight vowel epenthesis occurs in the clusters consisting of a plosive followed by , in those beginning , and in the cluster .
After the initial consonant or consonant cluster comes the syllabic nucleus, which is one of the vowels listed above. This vowel may end the syllable or may be followed by a coda, which is a single consonant. If the syllable is stressed and the vowel is short, there must be a final consonant. All consonant sounds except and the aspirates can appear as the coda (although final is heard in some dialects, most notably in Northern Khmer).
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A minor syllable (unstressed syllable preceding the main syllable of a word) has a structure of CV-, CrV-, CVN- or CrVN- (where C is a consonant, V a vowel, and N a nasal consonant). The vowels in such syllables are usually short; in conversation they may be reduced to , although in careful or formal speech, including on television and radio, they are clearly articulated. An example of such a word is "mɔnuh, mɔnɨh, mĕəʾnuh" ('person'), pronounced , or more casually .
Stress.
Stress in Khmer falls on the final syllable of a word. Because of this predictable pattern, stress is non-phonemic in Khmer (it does not distinguish different meanings).
Primary stress falls on the final syllable, with secondary stress on every second syllable from the end. Thus in a three-syllable word, the first syllable has secondary stress; in a four-syllable word, the second syllable has secondary stress; in a five-syllable word, the first and third syllables have secondary stress, and so on. Long polysyllables are not often used in conversation.
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Most Khmer words consist of either one or two syllables. In most native disyllabic words, the first syllable is a minor (fully unstressed) syllable. Such words have been described as "sesquisyllabic" (i.e. as having one-and-a-half syllables). There are also some disyllabic words in which the first syllable does not behave as a minor syllable, but takes secondary stress. Most such words are compounds, but some are single morphemes (generally loanwords). An example is ('language'), pronounced .
Words with three or more syllables, if they are not compounds, are mostly loanwords, usually derived from Pali, Sanskrit, or more recently, French. They are nonetheless adapted to Khmer stress patterns.
Compounds, however, preserve the stress patterns of the constituent words. Thus , the name of a kind of cookie (literally 'bird's nest'), is pronounced , with secondary stress on the second rather than the first syllable, because it is composed of the words ('nest') and ('bird').
Phonation and tone.
Khmer once had a phonation distinction in its vowels, but this now survives only in the most archaic dialect (Western Khmer). The distinction arose historically when vowels after Old Khmer voiced consonants became breathy voiced and diphthongized; for example became . When consonant voicing was lost, the distinction was maintained by the vowel (); later the phonation disappeared as well (). These processes explain the origin of what are now called a-series and o-series consonants in the Khmer script.
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Although most Cambodian dialects are not tonal, the colloquial Phnom Penh dialect has developed a tonal contrast (level versus peaking tone) as a by-product of the elision of .
Intonation.
Intonation often conveys semantic context in Khmer, as in distinguishing declarative statements, questions and exclamations. The available grammatical means of making such distinctions are not always used, or may be ambiguous; for example, the final interrogative particle can also serve as an emphasizing (or in some cases negating) particle.
The intonation pattern of a typical Khmer declarative phrase is a steady rise throughout followed by an abrupt drop on the last syllable.
Other intonation contours signify a different type of phrase such as the "full doubt" interrogative, similar to yes–no questions in English. Full doubt interrogatives remain fairly even in tone throughout, but rise sharply towards the end.
Exclamatory phrases follow the typical steadily rising pattern, but rise sharply on the last syllable instead of falling.
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Grammar.
Khmer is primarily an analytic language with no inflection. Syntactic relations are mainly determined by word order. Old and Middle Khmer used particles to mark grammatical categories and many of these have survived in Modern Khmer but are used sparingly, mostly in literary or formal language. Khmer makes extensive use of auxiliary verbs, "directionals" and serial verb construction. Colloquial Khmer is a zero copula language, instead preferring predicative adjectives (and even predicative nouns) unless using a copula for emphasis or to avoid ambiguity in more complex sentences. Basic word order is subject–verb–object (SVO), although subjects are often dropped; prepositions are used rather than postpositions.
Topic-Comment constructions are common and the language is generally head-initial (modifiers follow the words they modify). Some grammatical processes are still not fully understood by western scholars. For example, it is not clear if certain features of Khmer grammar, such as actor nominalization, should be treated as a morphological process or a purely syntactic device, and some derivational morphology seems "purely decorative" and performs no known syntactic work.
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Lexical categories have been hard to define in Khmer. Henri Maspero, an early scholar of Khmer, claimed the language had no parts of speech, while a later scholar, Judith Jacob, posited four parts of speech and innumerable particles. John Haiman, on the other hand, identifies "a couple dozen" parts of speech in Khmer with the caveat that Khmer words have the freedom to perform a variety of syntactic functions depending on such factors as word order, relevant particles, location within a clause, intonation and context. Some of the more important lexical categories and their function are demonstrated in the following example sentence taken from a hospital brochure:
Morphology.
Modern Khmer is an isolating language, which means that it uses little productive morphology. There is some derivation by means of prefixes and infixes, but this is a remnant of Old Khmer and not always productive in the modern language. Khmer morphology is evidence of a historical process through which the language was, at some point in the past, changed from being an agglutinative language to adopting an isolating typology. Affixed forms are lexicalized and cannot be used productively to form new words. Below are some of the most common affixes with examples as given by Huffman.
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Compounding in Khmer is a common derivational process that takes two forms, coordinate compounds and repetitive compounds. Coordinate compounds join two unbound morphemes (independent words) of similar meaning to form a compound signifying a concept more general than either word alone. Coordinate compounds join either two nouns or two verbs. Repetitive compounds, one of the most productive derivational features of Khmer, use reduplication of an entire word to derive words whose meaning depends on the class of the reduplicated word. A repetitive compound of a noun indicates plurality or generality while that of an adjectival verb could mean either an intensification or plurality.
Coordinate compounds:
Repetitive compounds:
Nouns and pronouns.
Khmer nouns do not inflect for grammatical gender or singular/plural. There are no articles, but indefiniteness is often expressed by the word for "one" ( ) following the noun as in ( "a dog"). Plurality can be marked by postnominal particles, numerals, or reduplication of a following adjective, which, although similar to intensification, is usually not ambiguous due to context.
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Classifying particles are used after numerals, but are not always obligatory as they are in Thai or Chinese, for example, and are often dropped in colloquial speech. Khmer nouns are divided into two groups: mass nouns, which take classifiers; and specific, nouns, which do not. The overwhelming majority are mass nouns.
Possession is colloquially expressed by word order. The possessor is placed after the thing that is possessed. Alternatively, in more complex sentences or when emphasis is required, a possessive construction using the word (, "property, object") may be employed. In formal and literary contexts, the possessive particle () is used:
Pronouns are subject to a complicated system of social register, the choice of pronoun depending on the perceived relationships between speaker, audience and referent (see Social registers below). Khmer exhibits pronoun avoidance, so kinship terms, nicknames and proper names are often used instead of pronouns (including for the first person) among intimates. Subject pronouns are frequently dropped in colloquial conversation.
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Adjectives, verbs and verb phrases may be made into nouns by the use of nominalization particles. Three of the more common particles used to create nouns are , , and . These particles are prefixed most often to verbs to form abstract nouns. The latter, derived from Sanskrit, also occurs as a suffix in fixed forms borrowed from Sanskrit and Pali such as ("health") from ("to be healthy").
Adjectives and adverbs.
Adjectives, demonstratives and numerals follow the noun they modify. Adverbs likewise follow the verb. Morphologically, adjectives and adverbs are not distinguished, with many words often serving either function. Adjectives are also employed as verbs as Khmer sentences rarely use a copula.
Degrees of comparison are constructed syntactically. Comparatives are expressed using the word : "A X [B]" (A is more X [than B]). The most common way to express superlatives is with : "A X " (A is the most X). Intensity is also expressed syntactically, similar to other languages of the region, by reduplication or with the use of intensifiers.
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Verbs.
As is typical of most East Asian languages, Khmer verbs do not inflect at all; tense, aspect and mood can be expressed using auxiliary verbs, particles (such as , placed before a verb to express continuous aspect) and adverbs (such as "yesterday", "earlier", "tomorrow"), or may be understood from context. Serial verb construction is quite common.
Khmer verbs are a relatively open class and can be divided into two types, main verbs and auxiliary verbs. Huffman defined a Khmer verb as "any word that can be (negated)", and further divided main verbs into three classes.
Transitive verbs are verbs that may be followed by a direct object:
Intransitive verbs are verbs that can not be followed by an object:
Adjectival verbs are a word class that has no equivalent in English. When modifying a noun or verb, they function as adjectives or adverbs, respectively, but they may also be used as main verbs equivalent to English "be + "adjective"".
Syntax.
Syntax is the rules and processes that describe how sentences are formed in a particular language, how words relate to each other within clauses or phrases and how those phrases relate to each other within a sentence to convey meaning. Khmer syntax is very analytic. Relationships between words and phrases are signified primarily by word order supplemented with auxiliary verbs and, particularly in formal and literary registers, grammatical marking particles. Grammatical phenomena such as negation and aspect are marked by particles while interrogative sentences are marked either by particles or interrogative words equivalent to English "wh-words".
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A complete Khmer sentence consists of four basic elements—an optional topic, an optional subject, an obligatory predicate, and various adverbials and particles. The topic and subject are noun phrases, predicates are verb phrases and another noun phrase acting as an object or verbal attribute often follows the predicate.
Basic constituent order.
When combining these noun and verb phrases into a sentence the order is typically SVO:
When both a direct object and indirect object are present without any grammatical markers, the preferred order is SV(DO)(IO). In such a case, if the direct object phrase contains multiple components, the indirect object immediately follows the noun of the direct object phrase and the direct object's modifiers follow the indirect object:
This ordering of objects can be changed and the meaning clarified with the inclusion of particles. The word , which normally means "to arrive" or "towards", can be used as a preposition meaning "to":
Alternatively, the indirect object could precede the direct object if the object-marking preposition were used:
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However, in spoken discourse OSV is possible when emphasizing the object in a topic–comment-like structure.
Noun phrase.
The noun phrase in Khmer typically has the following structure:
The elements in parentheses are optional. Honorifics are a class of words that serve to index the social status of the referent. Honorifics can be kinship terms or personal names, both of which are often used as first and second person pronouns, or specialized words such as ('god') before royal and religious objects. The most common demonstratives are ('this, these') and ('that, those'). The word ('those over there') has a more distal or vague connotation.
If the noun phrase contains a possessive adjective, it follows the noun and precedes the numeral. If a descriptive attribute co-occurs with a possessive, the possessive construction () is expected.
Some examples of typical Khmer noun phrases are:
The Khmer particle marked attributes in Old Khmer noun phrases and is used in formal and literary language to signify that what precedes is the noun and what follows is the attribute. Modern usage may carry the connotation of mild intensity.
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Verb phrase.
Khmer verbs are completely uninflected, and once a subject or topic has been introduced or is clear from context the noun phrase may be dropped. Thus, the simplest possible sentence in Khmer consists of a single verb. For example, 'to go' on its own can mean "I'm going.", "He went.", "They've gone.", "Let's go.", etc. This also results in long strings of verbs such as:
Khmer uses three verbs for what translates into English as the copula. The general copula is ; it is used to convey identity with nominal predicates. For locative predicates, the copula is . The verb is the "existential" copula meaning "there is" or "there exists".
Negation is achieved by putting before the verb and the particle at the end of the sentence or clause. In colloquial speech, verbs can also be negated without the need for a final particle, by placing before them.
Past tense can be conveyed by adverbs, such as "yesterday" or by the use of perfective particles such as
Different senses of future action can also be expressed by the use of adverbs like "tomorrow" or by the future tense marker , which is placed immediately before the verb, or both:
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Imperatives are often unmarked. For example, in addition to the meanings given above, the "sentence" can also mean "Go!". Various words and particles may be added to the verb to soften the command to varying degrees, including to the point of politeness (jussives):
Prohibitives take the form " + " and also are often softened by the addition of the particle to the end of the phrase.
Questions.
There are three basic types of questions in Khmer. Questions requesting specific information use question words. Polar questions are indicated with interrogative particles, most commonly , a homonym of the negation particle. Tag questions are indicated with various particles and rising inflection. The SVO word order is generally not inverted for questions.
In more formal contexts and in polite speech, questions are also marked at their beginning by the particle .
Passive voice.
Khmer does not have a passive voice, but there is a construction utilizing the main verb ("to hit", "to be correct", "to affect") as an auxiliary verb meaning "to be subject to" or "to undergo"—which results in sentences that are translated to English using the passive voice.
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Clause syntax.
Complex sentences are formed in Khmer by the addition of one or more clauses to the main clause. The various types of clauses in Khmer include the coordinate clause, the relative clause and the subordinate clause. Word order in clauses is the same for that of the basic sentences described above. Coordinate clauses do not necessarily have to be marked; they can simply follow one another. When explicitly marked, they are joined by words similar to English conjunctions such as ("and") and ("and then") or by clause-final conjunction-like adverbs and , both of which can mean "also" or "and also"; disjunction is indicated by ("or").
Relative clauses can be introduced by ("that") but, similar to coordinate clauses, often simply follow the main clause. For example, both phrases below can mean "the hospital bed that has wheels".
Relative clauses are more likely to be introduced with if they do not immediately follow the head noun. Khmer subordinate conjunctions always precede a subordinate clause. Subordinate conjunctions include words such as ("because"), ("seems as if") and ("in order to").
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Numerals.
Counting in Khmer is based on a biquinary system: the numbers from 6 to 9 have the form "five one", "five two", etc. The words for multiples of ten from 30 to 90 are not related to the basic Khmer numbers, but are Chinese in origin, and probably came to Khmer via Thai. Khmer numerals, which were inherited directly from Indian numerals, are used more widely than Western numerals, which like Khmer numerals were inherited from Indian, but first passed through the Arabic numerals before reaching the west.
The principal number words are listed in the following table, which gives Western and Khmer digits, Khmer spelling and IPA transcription.
Intermediate numbers are formed by compounding the above elements. Powers of ten are denoted by loan words: (100), (1,000), (10,000), (100,000) and (1,000,000) from Thai and (10,000,000) from Sanskrit.
Ordinal numbers are formed by placing the particle before the corresponding cardinal number.
Social registers.
Khmer employs a system of registers in which the speaker must always be conscious of the social status of the person spoken to. The different registers, which include those used for common speech, polite speech, speaking to or about royals and speaking to or about monks, employ alternate verbs, names of body parts and pronouns. As an example, the word for "to eat" used between intimates or in reference to animals is . Used in polite reference to commoners, it is . When used of those of higher social status, it is or . For monks the word is and for royals, . Another result is that the pronominal system is complex and full of honorific variations, just a few of which are shown in the table below.
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Writing system.
Khmer is written with the Khmer script, an abugida developed from the Pallava script of India before the 7th century when the first known inscription appeared. Written left-to-right with vowel signs that can be placed after, before, above or below the consonant they follow, the Khmer script is similar in appearance and usage to Thai and Lao, both of which were based on the Khmer system. The Khmer script is also distantly related to the Mon–Burmese script. Within Cambodia, literacy in the Khmer alphabet is estimated at 77.6%.
Consonant symbols in Khmer are divided into two groups, or series. The first series carries the inherent vowel while the second series carries the inherent vowel . The Khmer names of the series, ('voiceless') and ('voiced'), respectively, indicate that the second series consonants were used to represent the voiced phonemes of Old Khmer. As the voicing of stops was lost, however, the contrast shifted to the phonation of the attached vowels, which, in turn, evolved into a simple difference of vowel quality, often by diphthongization. This process has resulted in the Khmer alphabet having two symbols for most consonant phonemes and each vowel symbol having two possible readings, depending on the series of the initial consonant:
Examples.
The following text is from Article 1 of the Universal Declaration of Human Rights.
External links.
<section begin="list-of-glossing-abbreviations"/>
NOUN:noun
VERB:verb
OBJ:object
OM:object marker
MARKER:marker
REL:relative
COHORT:cohortative
DIR:directional
COMPL:complement
RESP:respectful
<section end="list-of-glossing-abbreviations"/> |
Central processing unit
A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs).
The form, design, and implementation of CPUs have changed over time, but their fundamental operation remains almost unchanged. Principal components of a CPU include the arithmetic–logic unit (ALU) that performs arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations, and a control unit that orchestrates the fetching (from memory), decoding and execution (of instructions) by directing the coordinated operations of the ALU, registers, and other components. Modern CPUs devote a lot of semiconductor area to caches and instruction-level parallelism to increase performance and to CPU modes to support operating systems and virtualization.
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Most modern CPUs are implemented on integrated circuit (IC) microprocessors, with one or more CPUs on a single IC chip. Microprocessor chips with multiple CPUs are called "multi-core processors". The individual physical CPUs, called processor cores, can also be multithreaded to support CPU-level multithreading.
An IC that contains a CPU may also contain memory, peripheral interfaces, and other components of a computer; such integrated devices are variously called microcontrollers or systems on a chip (SoC).
History.
Early computers such as the ENIAC had to be physically rewired to perform different tasks, which caused these machines to be called "fixed-program computers". The "central processing unit" term has been in use since as early as 1955. Since the term "CPU" is generally defined as a device for software (computer program) execution, the earliest devices that could rightly be called CPUs came with the advent of the stored-program computer.
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Early CPUs were custom designs used as part of a larger and sometimes distinctive computer. However, this method of designing custom CPUs for a particular application has largely given way to the development of multi-purpose processors produced in large quantities. This standardization began in the era of discrete transistor mainframes and minicomputers, and has rapidly accelerated with the popularization of the integrated circuit (IC). The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in electronic devices ranging from automobiles to cellphones, and sometimes even in toys.
While von Neumann is most often credited with the design of the stored-program computer because of his design of EDVAC, and the design became known as the von Neumann architecture, others before him, such as Konrad Zuse, had suggested and implemented similar ideas. The so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also used a stored-program design using punched paper tape rather than electronic memory. The key difference between the von Neumann and Harvard architectures is that the latter separates the storage and treatment of CPU instructions and data, while the former uses the same memory space for both. Most modern CPUs are primarily von Neumann in design, but CPUs with the Harvard architecture are seen as well, especially in embedded applications; for instance, the Atmel AVR microcontrollers are Harvard-architecture processors.
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Relays and vacuum tubes (thermionic tubes) were commonly used as switching elements; a useful computer requires thousands or tens of thousands of switching devices. The overall speed of a system is dependent on the speed of the switches. Vacuum-tube computers such as EDVAC tended to average eight hours between failures, whereas relay computers—such as the slower but earlier Harvard Mark I—failed very rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded generally outweighed the reliability problems. Most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs. Clock signal frequencies ranging from 100 kHz to 4 MHz were very common at this time, limited largely by the speed of the switching devices they were built with.
Transistor CPUs.
The design complexity of CPUs increased as various technologies facilitated the building of smaller and more reliable electronic devices. The first such improvement came with the advent of the transistor. Transistorized CPUs during the 1950s and 1960s no longer had to be built out of bulky, unreliable, and fragile switching elements, like vacuum tubes and relays. With this improvement, more complex and reliable CPUs were built onto one or several printed circuit boards containing discrete (individual) components.
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In 1964, IBM introduced its IBM System/360 computer architecture that was used in a series of computers capable of running the same programs with different speeds and performances. This was significant at a time when most electronic computers were incompatible with one another, even those made by the same manufacturer. To facilitate this improvement, IBM used the concept of a microprogram (often called "microcode"), which still sees widespread use in modern CPUs. The System/360 architecture was so popular that it dominated the mainframe computer market for decades and left a legacy that is continued by similar modern computers like the IBM zSeries. In 1965, Digital Equipment Corporation (DEC) introduced another influential computer aimed at the scientific and research markets—the PDP-8.
Transistor-based computers had several distinct advantages over their predecessors. Aside from facilitating increased reliability and lower power consumption, transistors also allowed CPUs to operate at much higher speeds because of the short switching time of a transistor in comparison to a tube or relay. The increased reliability and dramatically increased speed of the switching elements, which were almost exclusively transistors by this time; CPU clock rates in the tens of megahertz were easily obtained during this period. Additionally, while discrete transistor and IC CPUs were in heavy usage, new high-performance designs like single instruction, multiple data (SIMD) vector processors began to appear. These early experimental designs later gave rise to the era of specialized supercomputers like those made by Cray Inc and Fujitsu Ltd.
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Small-scale integration CPUs.
During this period, a method of manufacturing many interconnected transistors in a compact space was developed. The integrated circuit (IC) allowed a large number of transistors to be manufactured on a single semiconductor-based die, or "chip". At first, only very basic non-specialized digital circuits such as NOR gates were miniaturized into ICs. CPUs based on these "building block" ICs are generally referred to as "small-scale integration" (SSI) devices. SSI ICs, such as the ones used in the Apollo Guidance Computer, usually contained up to a few dozen transistors. To build an entire CPU out of SSI ICs required thousands of individual chips, but still consumed much less space and power than earlier discrete transistor designs.
IBM's System/370, follow-on to the System/360, used SSI ICs rather than Solid Logic Technology discrete-transistor modules. DEC's PDP-8/I and KI10 PDP-10 also switched from the individual transistors used by the PDP-8 and PDP-10 to SSI ICs, and their extremely popular PDP-11 line was originally built with SSI ICs, but was eventually implemented with LSI components once these became practical.
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Large-scale integration CPUs.
Lee Boysel published influential articles, including a 1967 "manifesto", which described how to build the equivalent of a 32-bit mainframe computer from a relatively small number of large-scale integration circuits (LSI). The only way to build LSI chips, which are chips with a hundred or more gates, was to build them using a metal–oxide–semiconductor (MOS) semiconductor manufacturing process (either PMOS logic, NMOS logic, or CMOS logic). However, some companies continued to build processors out of bipolar transistor–transistor logic (TTL) chips because bipolar junction transistors were faster than MOS chips up until the 1970s (a few companies such as Datapoint continued to build processors out of TTL chips until the early 1980s). In the 1960s, MOS ICs were slower and initially considered useful only in applications that required low power. Following the development of silicon-gate MOS technology by Federico Faggin at Fairchild Semiconductor in 1968, MOS ICs largely replaced bipolar TTL as the standard chip technology in the late 1970s.
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As the microelectronic technology advanced, an increasing number of transistors were placed on ICs, decreasing the number of individual ICs needed for a complete CPU. MSI and LSI ICs increased transistor counts to hundreds, and then thousands. By 1968, the number of ICs required to build a complete CPU had been reduced to 24 ICs of eight different types, with each IC containing roughly 1000 MOSFETs. In stark contrast with its SSI and MSI predecessors, the first LSI implementation of the PDP-11 contained a CPU composed of only four LSI integrated circuits.
Microprocessors.
Since microprocessors were first introduced they have almost completely overtaken all other central processing unit implementation methods. The first commercially available microprocessor, made in 1971, was the Intel 4004, and the first widely used microprocessor, made in 1974, was the Intel 8080. Mainframe and minicomputer manufacturers of the time launched proprietary IC development programs to upgrade their older computer architectures, and eventually produced instruction set compatible microprocessors that were backward-compatible with their older hardware and software. Combined with the advent and eventual success of the ubiquitous personal computer, the term "CPU" is now applied almost exclusively to microprocessors. Several CPUs (denoted "cores") can be combined in a single processing chip.
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Previous generations of CPUs were implemented as discrete components and numerous small integrated circuits (ICs) on one or more circuit boards. Microprocessors, on the other hand, are CPUs manufactured on a very small number of ICs; usually just one. The overall smaller CPU size, as a result of being implemented on a single die, means faster switching time because of physical factors like decreased gate parasitic capacitance. This has allowed synchronous microprocessors to have clock rates ranging from tens of megahertz to several gigahertz. Additionally, the ability to construct exceedingly small transistors on an IC has increased the complexity and number of transistors in a single CPU many fold. This widely observed trend is described by Moore's law, which had proven to be a fairly accurate predictor of the growth of CPU (and other IC) complexity until 2016.
While the complexity, size, construction and general form of CPUs have changed enormously since 1950, the basic design and function has not changed much at all. Almost all common CPUs today can be very accurately described as von Neumann stored-program machines. As Moore's law no longer holds, concerns have arisen about the limits of integrated circuit transistor technology. Extreme miniaturization of electronic gates is causing the effects of phenomena like electromigration and subthreshold leakage to become much more significant. These newer concerns are among the many factors causing researchers to investigate new methods of computing such as the quantum computer, as well as to expand the use of parallelism and other methods that extend the usefulness of the classical von Neumann model.
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Operation.
The fundamental operation of most CPUs, regardless of the physical form they take, is to execute a sequence of stored instructions that is called a program. The instructions to be executed are kept in some kind of computer memory. Nearly all CPUs follow the fetch, decode and execute steps in their operation, which are collectively known as the instruction cycle.
After the execution of an instruction, the entire process repeats, with the next instruction cycle normally fetching the next-in-sequence instruction because of the incremented value in the program counter. If a jump instruction was executed, the program counter will be modified to contain the address of the instruction that was jumped to and program execution continues normally. In more complex CPUs, multiple instructions can be fetched, decoded and executed simultaneously. This section describes what is generally referred to as the "classic RISC pipeline", which is quite common among the simple CPUs used in many electronic devices (often called microcontrollers). It largely ignores the important role of CPU cache, and therefore the access stage of the pipeline.
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Some instructions manipulate the program counter rather than producing result data directly; such instructions are generally called "jumps" and facilitate program behavior like loops, conditional program execution (through the use of a conditional jump), and existence of functions. In some processors, some other instructions change the state of bits in a "flags" register. These flags can be used to influence how a program behaves, since they often indicate the outcome of various operations. For example, in such processors a "compare" instruction evaluates two values and sets or clears bits in the flags register to indicate which one is greater or whether they are equal; one of these flags could then be used by a later jump instruction to determine program flow.
Fetch.
Fetch involves retrieving an instruction (which is represented by a number or sequence of numbers) from program memory. The instruction's location (address) in program memory is determined by the program counter (PC; called the "instruction pointer" in Intel x86 microprocessors), which stores a number that identifies the address of the next instruction to be fetched. After an instruction is fetched, the PC is incremented by the length of the instruction so that it will contain the address of the next instruction in the sequence. Often, the instruction to be fetched must be retrieved from relatively slow memory, causing the CPU to stall while waiting for the instruction to be returned. This issue is largely addressed in modern processors by caches and pipeline architectures (see below).
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Decode.
The instruction that the CPU fetches from memory determines what the CPU will do. In the decode step, performed by binary decoder circuitry known as the "instruction decoder", the instruction is converted into signals that control other parts of the CPU.
The way in which the instruction is interpreted is defined by the CPU's instruction set architecture (ISA). Often, one group of bits (that is, a "field") within the instruction, called the opcode, indicates which operation is to be performed, while the remaining fields usually provide supplemental information required for the operation, such as the operands. Those operands may be specified as a constant value (called an immediate value), or as the location of a value that may be a processor register or a memory address, as determined by some addressing mode.
In some CPU designs, the instruction decoder is implemented as a hardwired, unchangeable binary decoder circuit. In others, a microprogram is used to translate instructions into sets of CPU configuration signals that are applied sequentially over multiple clock pulses. In some cases the memory that stores the microprogram is rewritable, making it possible to change the way in which the CPU decodes instructions.
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Execute.
After the fetch and decode steps, the execute step is performed. Depending on the CPU architecture, this may consist of a single action or a sequence of actions. During each action, control signals electrically enable or disable various parts of the CPU so they can perform all or part of the desired operation. The action is then completed, typically in response to a clock pulse. Very often the results are written to an internal CPU register for quick access by subsequent instructions. In other cases results may be written to slower, but less expensive and higher capacity main memory.
For example, if an instruction that performs addition is to be executed, registers containing operands (numbers to be summed) are activated, as are the parts of the arithmetic logic unit (ALU) that perform addition. When the clock pulse occurs, the operands flow from the source registers into the ALU, and the sum appears at its output. On subsequent clock pulses, other components are enabled (and disabled) to move the output (the sum of the operation) to storage (e.g., a register or memory). If the resulting sum is too large (i.e., it is larger than the ALU's output word size), an arithmetic overflow flag will be set, influencing the next operation.
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Structure and implementation.
Hardwired into a CPU's circuitry is a set of basic operations it can perform, called an instruction set. Such operations may involve, for example, adding or subtracting two numbers, comparing two numbers, or jumping to a different part of a program. Each instruction is represented by a unique combination of bits, known as the machine language opcode. While processing an instruction, the CPU decodes the opcode (via a binary decoder) into control signals, which orchestrate the behavior of the CPU. A complete machine language instruction consists of an opcode and, in many cases, additional bits that specify arguments for the operation (for example, the numbers to be summed in the case of an addition operation). Going up the complexity scale, a machine language program is a collection of machine language instructions that the CPU executes.
The actual mathematical operation for each instruction is performed by a combinational logic circuit within the CPU's processor known as the arithmetic–logic unit or ALU. In general, a CPU executes an instruction by fetching it from memory, using its ALU to perform an operation, and then storing the result to memory. Besides the instructions for integer mathematics and logic operations, various other machine instructions exist, such as those for loading data from memory and storing it back, branching operations, and mathematical operations on floating-point numbers performed by the CPU's floating-point unit (FPU).
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Control unit.
The control unit (CU) is a component of the CPU that directs the operation of the processor. It tells the computer's memory, arithmetic and logic unit and input and output devices how to respond to the instructions that have been sent to the processor.
It directs the operation of the other units by providing timing and control signals. Most computer resources are managed by the CU. It directs the flow of data between the CPU and the other devices. John von Neumann included the control unit as part of the von Neumann architecture. In modern computer designs, the control unit is typically an internal part of the CPU with its overall role and operation unchanged since its introduction.
Arithmetic logic unit.
The arithmetic logic unit (ALU) is a digital circuit within the processor that performs integer arithmetic and bitwise logic operations. The inputs to the ALU are the data words to be operated on (called operands), status information from previous operations, and a code from the control unit indicating which operation to perform. Depending on the instruction being executed, the operands may come from internal CPU registers, external memory, or constants generated by the ALU itself.
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When all input signals have settled and propagated through the ALU circuitry, the result of the performed operation appears at the ALU's outputs. The result consists of both a data word, which may be stored in a register or memory, and status information that is typically stored in a special, internal CPU register reserved for this purpose.
Modern CPUs typically contain more than one ALU to improve performance.
Address generation unit.
The address generation unit (AGU), sometimes also called the address computation unit (ACU), is an execution unit inside the CPU that calculates addresses used by the CPU to access main memory. By having address calculations handled by separate circuitry that operates in parallel with the rest of the CPU, the number of CPU cycles required for executing various machine instructions can be reduced, bringing performance improvements.
While performing various operations, CPUs need to calculate memory addresses required for fetching data from the memory; for example, in-memory positions of array elements must be calculated before the CPU can fetch the data from actual memory locations. Those address-generation calculations involve different integer arithmetic operations, such as addition, subtraction, modulo operations, or bit shifts. Often, calculating a memory address involves more than one general-purpose machine instruction, which do not necessarily decode and execute quickly. By incorporating an AGU into a CPU design, together with introducing specialized instructions that use the AGU, various address-generation calculations can be offloaded from the rest of the CPU, and can often be executed quickly in a single CPU cycle.
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Capabilities of an AGU depend on a particular CPU and its architecture. Thus, some AGUs implement and expose more address-calculation operations, while some also include more advanced specialized instructions that can operate on multiple operands at a time. Some CPU architectures include multiple AGUs so more than one address-calculation operation can be executed simultaneously, which brings further performance improvements due to the superscalar nature of advanced CPU designs. For example, Intel incorporates multiple AGUs into its Sandy Bridge and Haswell microarchitectures, which increase bandwidth of the CPU memory subsystem by allowing multiple memory-access instructions to be executed in parallel.
Memory management unit (MMU).
Many microprocessors (in smartphones and desktop, laptop, server computers) have a memory management unit, translating logical addresses into physical RAM addresses, providing memory protection and paging abilities, useful for virtual memory. Simpler processors, especially microcontrollers, usually don't include an MMU.
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Cache.
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, closer to a processor core, which stores copies of the data from frequently used main memory locations. Most CPUs have different independent caches, including instruction and data caches, where the data cache is usually organized as a hierarchy of several cache levels (L1, L2, L3, L4, etc.). Each ascending cache level is typically slower but larger than the preceding level with L1 being the fastest and the closest to the CPU.
All modern (fast) CPUs (with few specialized exceptions) have multiple levels of CPU caches. The first CPUs that used a cache had only one level of cache; unlike later level 1 caches, it was not split into L1d (for data) and L1i (for instructions). Almost all current CPUs with caches have a split L1 cache. They also have L2 caches and, for larger processors, L3 caches as well. The L2 cache is usually not split and acts as a common repository for the already split L1 cache. Every core of a multi-core processor has a dedicated L2 cache and is usually not shared between the cores. The L3 cache, and higher-level caches, are shared between the cores and are not split. An L4 cache is currently uncommon, and is generally on dynamic random-access memory (DRAM), rather than on static random-access memory (SRAM), on a separate die or chip. That was also the case historically with L1, while bigger chips have allowed integration of it and generally all cache levels, with the possible exception of the last level. Each extra level of cache tends to be bigger and is optimized differently.
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Other types of caches exist (that are not counted towards the "cache size" of the most important caches mentioned above), such as the translation lookaside buffer (TLB) that is part of the memory management unit (MMU) that most CPUs have.
Caches are generally sized in powers of two: 2, 8, 16 etc. KiB or MiB (for larger non-L1) sizes, although the IBM z13 has a 96 KiB L1 instruction cache.
Clock rate.
Most CPUs are synchronous circuits, which means they employ a clock signal to pace their sequential operations. The clock signal is produced by an external oscillator circuit that generates a consistent number of pulses each second in the form of a periodic square wave. The frequency of the clock pulses determines the rate at which a CPU executes instructions and, consequently, the faster the clock, the more instructions the CPU will execute each second.
To ensure proper operation of the CPU, the clock period is longer than the maximum time needed for all signals to propagate (move) through the CPU. In setting the clock period to a value well above the worst-case propagation delay, it is possible to design the entire CPU and the way it moves data around the "edges" of the rising and falling clock signal. This has the advantage of simplifying the CPU significantly, both from a design perspective and a component-count perspective. However, it also carries the disadvantage that the entire CPU must wait on its slowest elements, even though some portions of it are much faster. This limitation has largely been compensated for by various methods of increasing CPU parallelism (see below).
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However, architectural improvements alone do not solve all of the drawbacks of globally synchronous CPUs. For example, a clock signal is subject to the delays of any other electrical signal. Higher clock rates in increasingly complex CPUs make it more difficult to keep the clock signal in phase (synchronized) throughout the entire unit. This has led many modern CPUs to require multiple identical clock signals to be provided to avoid delaying a single signal significantly enough to cause the CPU to malfunction. Another major issue, as clock rates increase dramatically, is the amount of heat that is dissipated by the CPU. The constantly changing clock causes many components to switch regardless of whether they are being used at that time. In general, a component that is switching uses more energy than an element in a static state. Therefore, as clock rate increases, so does energy consumption, causing the CPU to require more heat dissipation in the form of CPU cooling solutions.
One method of dealing with the switching of unneeded components is called clock gating, which involves turning off the clock signal to unneeded components (effectively disabling them). However, this is often regarded as difficult to implement and therefore does not see common usage outside of very low-power designs. One notable recent CPU design that uses extensive clock gating is the IBM PowerPC-based Xenon used in the Xbox 360; this reduces the power requirements of the Xbox 360.
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Clockless CPUs.
Another method of addressing some of the problems with a global clock signal is the removal of the clock signal altogether. While removing the global clock signal makes the design process considerably more complex in many ways, asynchronous (or clockless) designs carry marked advantages in power consumption and heat dissipation in comparison with similar synchronous designs. While somewhat uncommon, entire asynchronous CPUs have been built without using a global clock signal. Two notable examples of this are the ARM compliant AMULET and the MIPS R3000 compatible MiniMIPS.
Rather than totally removing the clock signal, some CPU designs allow certain portions of the device to be asynchronous, such as using asynchronous ALUs in conjunction with superscalar pipelining to achieve some arithmetic performance gains. While it is not altogether clear whether totally asynchronous designs can perform at a comparable or better level than their synchronous counterparts, it is evident that they do at least excel in simpler math operations. This, combined with their excellent power consumption and heat dissipation properties, makes them very suitable for embedded computers.
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Voltage regulator module.
Many modern CPUs have a die-integrated power managing module which regulates on-demand voltage supply to the CPU circuitry allowing it to keep balance between performance and power consumption.
Integer range.
Every CPU represents numerical values in a specific way. For example, some early digital computers represented numbers as familiar decimal (base 10) numeral system values, and others have employed more unusual representations such as bi-quinary coded decimal (base 2-5) or ternary (base 3). Nearly all modern CPUs represent numbers in binary form, with each digit being represented by some two-valued physical quantity such as a "high" or "low" voltage.
Related to numeric representation is the size and precision of integer numbers that a CPU can represent. In the case of a binary CPU, this is measured by the number of bits (significant digits of a binary encoded integer) that the CPU can process in one operation, which is commonly called "word size", "bit width", "data path width", "integer precision", or "integer size". A CPU's integer size determines the range of integer values on which it can directly operate. For example, an 8-bit CPU can directly manipulate integers represented by eight bits, which have a range of 256 (28) discrete integer values.
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Integer range can also affect the number of memory locations the CPU can directly address (an address is an integer value representing a specific memory location). For example, if a binary CPU uses 32 bits to represent a memory address then it can directly address 232 memory locations. To circumvent this limitation and for various other reasons, some CPUs use mechanisms (such as memory management or bank switching) that allow additional memory to be addressed.
CPUs with larger word sizes require more circuitry and consequently are physically larger, cost more and consume more power (and therefore generate more heat). As a result, smaller 4- or 8-bit microcontrollers are commonly used in modern applications even though CPUs with much larger word sizes (such as 16, 32, 64, even 128-bit) are available. When higher performance is required, however, the benefits of a larger word size (larger data ranges and address spaces) may outweigh the disadvantages. A CPU can have internal data paths shorter than the word size to reduce size and cost. For example, even though the IBM System/360 instruction set architecture was a 32-bit instruction set, the System/360 Model 30 and Model 40 had 8-bit data paths in the arithmetic logical unit, so that a 32-bit add required four cycles, one for each 8 bits of the operands, and, even though the Motorola 68000 series instruction set was a 32-bit instruction set, the Motorola 68000 and Motorola 68010 had 16-bit data paths in the arithmetic logical unit, so that a 32-bit add required two cycles.
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To gain some of the advantages afforded by both lower and higher bit lengths, many instruction sets have different bit widths for integer and floating-point data, allowing CPUs implementing that instruction set to have different bit widths for different portions of the device. For example, the IBM System/360 instruction set was primarily 32 bit, but supported 64-bit floating-point values to facilitate greater accuracy and range in floating-point numbers. The System/360 Model 65 had an 8-bit adder for decimal and fixed-point binary arithmetic and a 60-bit adder for floating-point arithmetic. Many later CPU designs use similar mixed bit width, especially when the processor is meant for general-purpose use where a reasonable balance of integer and floating-point capability is required.
Parallelism.
The description of the basic operation of a CPU offered in the previous section describes the simplest form that a CPU can take. This type of CPU, usually referred to as "subscalar", operates on and executes one instruction on one or two pieces of data at a time, that is less than one instruction per clock cycle ().
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This process gives rise to an inherent inefficiency in subscalar CPUs. Since only one instruction is executed at a time, the entire CPU must wait for that instruction to complete before proceeding to the next instruction. As a result, the subscalar CPU gets "hung up" on instructions which take more than one clock cycle to complete execution. Even adding a second execution unit (see below) does not improve performance much; rather than one pathway being hung up, now two pathways are hung up and the number of unused transistors is increased. This design, wherein the CPU's execution resources can operate on only one instruction at a time, can only possibly reach "scalar" performance (one instruction per clock cycle, ). However, the performance is nearly always subscalar (less than one instruction per clock cycle, ).
Attempts to achieve scalar and better performance have resulted in a variety of design methodologies that cause the CPU to behave less linearly and more in parallel. When referring to parallelism in CPUs, two terms are generally used to classify these design techniques:
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Each methodology differs both in the ways in which they are implemented, as well as the relative effectiveness they afford in increasing the CPU's performance for an application.
Instruction-level parallelism.
One of the simplest methods for increased parallelism is to begin the first steps of instruction fetching and decoding before the prior instruction finishes executing. This is a technique known as instruction pipelining, and is used in almost all modern general-purpose CPUs. Pipelining allows multiple instruction to be executed at a time by breaking the execution pathway into discrete stages. This separation can be compared to an assembly line, in which an instruction is made more complete at each stage until it exits the execution pipeline and is retired.
Pipelining does, however, introduce the possibility for a situation where the result of the previous operation is needed to complete the next operation; a condition often termed data dependency conflict. Therefore, pipelined processors must check for these sorts of conditions and delay a portion of the pipeline if necessary. A pipelined processor can become very nearly scalar, inhibited only by pipeline stalls (an instruction spending more than one clock cycle in a stage).
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