1.
University of Pennsylvania
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The University of Pennsylvania is a private Ivy League research university located in Philadelphia, Pennsylvania, United States. Incorporated as The Trustees of the University of Pennsylvania, Penn is one of 14 founding members of the Association of American Universities, the university coat of arms features a dolphin on the red chief, adopted directly from the Franklin familys own coat of arms. Penn was one of the first academic institutions to follow a multidisciplinary model pioneered by several European universities and it was also home to many other educational innovations. The first school of medicine in North America, the first collegiate school. With an endowment of $10.72 billion, Penn had the seventh largest endowment of all colleges in the United States, all of Penns schools exhibit very high research activity. In fiscal year 2015, Penns academic research budget was $851 million, over its history, the university has also produced many distinguished alumni. S. House of Representatives,8 signers of the United States Declaration of Independence, in addition, some 30 Nobel laureates,169 Guggenheim Fellows, and 80 members of the American Academy of Arts and Sciences, have been affiliated with Penn. In addition, Penn has produced a significant number of Fortune 500 CEOs, in 1740, a group of Philadelphians joined together to erect a great preaching hall for the traveling evangelist George Whitefield, who toured the American colonies delivering open air sermons. The building was designed and built by Edmund Woolley and was the largest building in the city at the time and it was initially planned to serve as a charity school as well, however, a lack of funds forced plans for the chapel and school to be suspended. According to Franklins autobiography, it was in 1743 when he first had the idea to establish an academy, however, Peters declined a casual inquiry from Franklin and nothing further was done for another six years. Unlike the other Colonial colleges that existed in 1749—Harvard, William and Mary, Yale, Franklin assembled a board of trustees from among the leading citizens of Philadelphia, the first such non-sectarian board in America. At the first meeting of the 24 members of the Board of Trustees the issue of where to locate the school was a prime concern. The original sponsors of the dormant building still owed considerable construction debts and asked Franklins group to assume their debts and, accordingly, on February 1,1750 the new board took over the building and trusts of the old board. On August 13,1751, the Academy of Philadelphia, using the hall at 4th and Arch Streets. A charity school also was chartered July 13,1753 in accordance with the intentions of the original New Building donors, June 16,1755, the College of Philadelphia was chartered, paving the way for the addition of undergraduate instruction. All three schools shared the same Board of Trustees and were considered to be part of the same institution, the institution of higher learning was known as the College of Philadelphia from 1755 to 1779. In 1779, not trusting then-provost the Rev. William Smiths Loyalist tendencies, the result was a schism, with Smith continuing to operate an attenuated version of the College of Philadelphia. In 1791 the Legislature issued a new charter, merging the two institutions into a new University of Pennsylvania with twelve men from each institution on the new Board of Trustees
2.
Philadelphia
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In 1682, William Penn, an English Quaker, founded the city to serve as capital of the Pennsylvania Colony. Philadelphia was one of the capitals in the Revolutionary War. In the 19th century, Philadelphia became an industrial center. It became a destination for African-Americans in the Great Migration. The areas many universities and colleges make Philadelphia a top international study destination, as the city has evolved into an educational, with a gross domestic product of $388 billion, Philadelphia ranks ninth among world cities and fourth in the nation. Philadelphia is the center of activity in Pennsylvania and is home to seven Fortune 1000 companies. The Philadelphia skyline is growing, with a market of almost 81,900 commercial properties in 2016 including several prominent skyscrapers. The city is known for its arts, culture, and rich history, Philadelphia has more outdoor sculptures and murals than any other American city. Fairmount Park, when combined with the adjacent Wissahickon Valley Park in the watershed, is one of the largest contiguous urban park areas in the United States. The 67 National Historic Landmarks in the city helped account for the $10 billion generated by tourism, Philadelphia is the only World Heritage City in the United States. Before Europeans arrived, the Philadelphia area was home to the Lenape Indians in the village of Shackamaxon, the Lenape are a Native American tribe and First Nations band government. They are also called Delaware Indians and their territory was along the Delaware River watershed, western Long Island. Most Lenape were pushed out of their Delaware homeland during the 18th century by expanding European colonies, Lenape communities were weakened by newly introduced diseases, mainly smallpox, and violent conflict with Europeans. Iroquois people occasionally fought the Lenape, surviving Lenape moved west into the upper Ohio River basin. The American Revolutionary War and United States independence pushed them further west, in the 1860s, the United States government sent most Lenape remaining in the eastern United States to the Indian Territory under the Indian removal policy. In the 21st century, most Lenape now reside in the US state of Oklahoma, with communities living also in Wisconsin, Ontario. The Dutch considered the entire Delaware River valley to be part of their New Netherland colony, in 1638, Swedish settlers led by renegade Dutch established the colony of New Sweden at Fort Christina and quickly spread out in the valley. In 1644, New Sweden supported the Susquehannocks in their defeat of the English colony of Maryland
3.
Pennsylvania
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Pennsylvania /ˌpɛnsᵻlˈveɪnjə/, officially the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. The Appalachian Mountains run through its middle, Pennsylvania is the 33rd largest, the 5th most populous, and the 9th most densely populated of the 50 United States. The states five most populous cities are Philadelphia, Pittsburgh, Allentown, Erie, the state capital, and its ninth-largest city, is Harrisburg. Pennsylvania has 140 miles of shoreline along Lake Erie and the Delaware Estuary. The state is one of the 13 original founding states of the United States, it came into being in 1681 as a result of a land grant to William Penn. Part of Pennsylvania, together with the present State of Delaware, had earlier been organized as the Colony of New Sweden and it was the second state to ratify the United States Constitution, on December 12,1787. Independence Hall, where the United States Declaration of Independence and United States Constitution were drafted, is located in the states largest city of Philadelphia, during the American Civil War, the Battle of Gettysburg, was fought in the south central region of the state. Valley Forge near Philadelphia was General Washingtons headquarters during the winter of 1777–78. Pennsylvania is 170 miles north to south and 283 miles east to west, of a total 46,055 square miles,44,817 square miles are land,490 square miles are inland waters, and 749 square miles are waters in Lake Erie. It is the 33rd largest state in the United States, Pennsylvania has 51 miles of coastline along Lake Erie and 57 miles of shoreline along the Delaware Estuary. Cities include Philadelphia, Reading, Lebanon and Lancaster in the southeast, Pittsburgh in the southwest, the tri-cities of Allentown, Bethlehem, the northeast includes the former anthracite coal mining communities of Scranton, Wilkes-Barre, Pittston City, and Hazleton. Erie is located in the northwest, the state has 5 regions, namely the Allegheny Plateau, Ridge and Valley, Atlantic Coastal Plain, Piedmont, and the Erie Plain. Straddling two major zones, the majority of the state, with the exception of the corner, has a humid continental climate. The largest city, Philadelphia, has characteristics of the humid subtropical climate that covers much of Delaware. Moving toward the interior of the state, the winter climate becomes colder, the number of cloudy days increase. Western areas of the state, particularly locations near Lake Erie, can receive over 100 inches of snowfall annually, the state may be subject to severe weather from spring through summer into fall. Tornadoes occur annually in the state, sometimes in large numbers, the Tuscarora Nation took up temporary residence in the central portion of Pennsylvania ca. Both the Dutch and the English claimed both sides of the Delaware River as part of their lands in America
4.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
5.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
6.
Betty Holberton
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Frances Elizabeth Betty Holberton was one of the six original programmers of ENIAC, the first general-purpose electronic digital computer. Holberton was born Frances Elizabeth Snyder in Philadelphia, Pennsylvania in 1917, on her first day of classes at the University of Pennsylvania, Holbertons math professor asked her if she wouldnt be better off at home raising children. Instead, Holberton decided to study journalism, because its curriculum let her travel far afield, journalism was also one of the few fields open to women as a career in the 1940s. During World War II while the men were fighting, the Army needed the women to compute ballistics trajectories, Holberton was hired by the Moore School of Engineering to work as a computor, and was soon chosen to be one of the six women to program the ENIAC. Their work on ENIAC earned each of them a place in the Women in Technology International Hall of Fame, in the beginning, because the ENIAC was classified, the women were only allowed to work with blueprints and wiring diagrams in order to program it. The ENIAC was unveiled on February 15,1946, at the University of Pennsylvania and it had cost around $487,000, equivalent to $6,740,000 in 2016. After World War II, Holberton worked at Remington Rand and the National Bureau of Standards and she was the Chief of the Programming Research Branch, Applied Mathematics Laboratory at the David Taylor Model Basin in 1959. She was one of those who wrote the first generative programming system, and wrote the first statistical analysis package, in 1953 she was made a supervisor of advanced programming in a part of the Navy’s Applied Math lab in Maryland, where she stayed until 1966. Holberton worked with John Mauchly to develop the C-10 instruction set for BINAC and she also participated in the development of early standards for the COBOL and FORTRAN programming languages with Grace Hopper. Later, as an employee of the National Bureau of Standards and she died on December 8,2001 in Rockville, Maryland, aged 84, due to heart disease, diabetes, and complications from a stroke she had suffered several years before. She was survived by her husband John Vaughn Holberton and her daughters Pamela and Priscilla, in 1997 she was the only woman of the original six who programmed the ENIAC to receive the Augusta Ada Lovelace Award, the highest award given by the Association of Women in Computing. Also in 1997, she received the IEEE Computer Pioneer Award from the IEEE Computer Society for developing the sort-merge generator which, according to IEEE, also in 1997, she was inducted into the Women in Technology International Hall of Fame, along with the other original ENIAC programmers. Holberton School, a school for software engineers based in San Francisco, was founded in her honor in 2015. Archived from the original on 2008-01-09, charles Babbage Institute, University of Minnesota, Minneapolis. UNIVAC Conference as well as interview by James Baker Ross, in the latter, Holberton discusses her education from 1940 through the 1960s and her experiences in the computing field. These include work with the Eckert-Mauchly Computer Corporation, David Taylor Model Basin, and she discusses her perceptions of cooperation and competition between members of these organizations and the difficulties she encountered as a woman. She recounts her work on the ENIAC and LARC computers, her design of operating systems, Frances E. Holberton Papers, circa 1950s-1980s. Charles Babbage Institute, University of Minnesota, chapter 5 Daughters of the Enchantress of Numbers and Grandma COBOL
7.
Ballistic Research Laboratory
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The Ballistic Research Laboratory at Aberdeen Proving Ground, Maryland was the center for the United States Armys research efforts in ballistics as well as vulnerability/lethality analysis. In 1992, the BRLs mission, personnel, and facilities were incorporated into the newly created Army Research Laboratory, the name was originally plural, reflecting subordinate laboratories for each of the ballistic disciplines, but these were eventually redesignated divisions of a single laboratory. Over the years, and particularly during World War II, BRLs permanent technical staff was augmented by a number of eminent scientists, among those was noted American astronomer Edwin P. The results of his studies was credited with greatly improving design, performance, other included members of the Scientific Advisory Committee which was established in 1940. Hirschfelder, Norman Ramsey, Robert G. Sachs, and L. H. Thomas. On March 27 of 1964, the U. S. Armys Ballistic Research Laboratory, according to the 36th U. S. Presidents Commission, played host to one of the most famous rifles in U. S. history. On that date, three marksmen test fired a Mannlicher–Carcano Type 38, the used by Lee Harvey Oswald to assassinate President John F. Kennedy on November 22 of 1963. Only one of the three expert marksmen was able to fire three shots somewhat close to the official time limit attributed to Oswald. Oswald shot at a moving target
8.
Computer
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A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. The ability of computers to follow a sequence of operations, called a program, such computers are used as control systems for a very wide variety of industrial and consumer devices. The Internet is run on computers and it millions of other computers. Since ancient times, simple manual devices like the abacus aided people in doing calculations, early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century, the first digital electronic calculating machines were developed during World War II. The speed, power, and versatility of computers has increased continuously and dramatically since then, conventionally, a modern computer consists of at least one processing element, typically a central processing unit, and some form of memory. The processing element carries out arithmetic and logical operations, and a sequencing, peripheral devices include input devices, output devices, and input/output devices that perform both functions. Peripheral devices allow information to be retrieved from an external source and this usage of the term referred to a person who carried out calculations or computations. The word continued with the same meaning until the middle of the 20th century, from the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations. The Online Etymology Dictionary gives the first attested use of computer in the 1640s, one who calculates, the Online Etymology Dictionary states that the use of the term to mean calculating machine is from 1897. The Online Etymology Dictionary indicates that the use of the term. 1945 under this name, theoretical from 1937, as Turing machine, devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick, later record keeping aids throughout the Fertile Crescent included calculi which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example, the abacus was initially used for arithmetic tasks. The Roman abacus was developed from used in Babylonia as early as 2400 BC. Since then, many forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, the Antikythera mechanism is believed to be the earliest mechanical analog computer, according to Derek J. de Solla Price. It was designed to calculate astronomical positions and it was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC
9.
Artillery
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Artillery is a class of large military weapons built to fire munitions far beyond the range and power of infantrys small arms. Early artillery development focused on the ability to breach fortifications, and led to heavy, as technology improved, lighter, more mobile field artillery developed for battlefield use. This development continues today, modern self-propelled artillery vehicles are highly mobile weapons of great versatility providing the largest share of an armys total firepower, in its earliest sense, the word artillery referred to any group of soldiers primarily armed with some form of manufactured weapon or armour. In common speech, the artillery is often used to refer to individual devices, along with their accessories and fittings. However, there is no generally recognised generic term for a gun, howitzer, mortar, and so forth, the United States uses artillery piece, the projectiles fired are typically either shot or shell. Shell is a widely used term for a projectile, which is a component of munitions. By association, artillery may also refer to the arm of service that customarily operates such engines, in the 20th Century technology based target acquisition devices, such as radar, and systems, such as sound ranging and flash spotting, emerged to acquire targets, primarily for artillery. These are usually operated by one or more of the artillery arms, Artillery originated for use against ground targets—against infantry, cavalry and other artillery. An early specialist development was coastal artillery for use against enemy ships, the early 20th Century saw the development of a new class of artillery for use against aircraft, anti-aircraft guns. Artillery is arguably the most lethal form of land-based armament currently employed, the majority of combat deaths in the Napoleonic Wars, World War I, and World War II were caused by artillery. In 1944, Joseph Stalin said in a speech that artillery was the God of War, although not called as such, machines performing the role recognizable as artillery have been employed in warfare since antiquity. The first references in the historical tradition begin at Syracuse in 399 BC. From the Middle Ages through most of the era, artillery pieces on land were moved by horse-drawn gun carriages. In the contemporary era, the artillery and crew rely on wheeled or tracked vehicles as transportation, Artillery used by naval forces has changed significantly also, with missiles replacing guns in surface warfare. The engineering designs of the means of delivery have likewise changed significantly over time, in some armies, the weapon of artillery is the projectile, not the equipment that fires it. The process of delivering fire onto the target is called gunnery, the actions involved in operating the piece are collectively called serving the gun by the detachment or gun crew, constituting either direct or indirect artillery fire. The term gunner is used in armed forces for the soldiers and sailors with the primary function of using artillery. The gunners and their guns are usually grouped in teams called either crews or detachments, several such crews and teams with other functions are combined into a unit of artillery, usually called a battery, although sometimes called a company
10.
External ballistics
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External ballistics or exterior ballistics is the part of ballistics that deals with the behavior of a projectile in flight. Gun-launched projectiles may be unpowered, deriving all their velocity from the propellants ignition until the exits the gun barrel. External ballistics is also concerned with the free-flight of other projectiles, such as balls, arrows etc. When in flight, the main or major forces acting on the projectile are gravity, drag, and if present, wind, if in powered fight, thrust, and if guided, the forces imparted by the control surfaces. In small arms external ballistics applications, gravity imparts a downward acceleration on the projectile, drag, or the air resistance, decelerates the projectile with a force proportional to the square of the velocity. Wind makes the projectile deviate from its trajectory, during flight, gravity, drag, and wind have a major impact on the path of the projectile, and must be accounted for when predicting how the projectile will travel. Meso variables can become significant for firearms users that have to deal with angled shot scenarios or extended ranges, at extremely long ranges, artillery must fire projectiles along trajectories that are not even approximately straight, they are closer to parabolic, although air resistance affects this. In super gun artillery cases, like the Paris gun, very subtle effects that are not covered in this article can further refine aiming solutions. The CP behind the CG condition yields stable projectile flight, meaning the projectile will not overturn during flight through the due to aerodynamic forces. Projectiles like small arms bullets and artillery shells must deal with their CP being in front of their CG, to stabilize such projectiles the projectile is spun around its longitudinal axis. The spinning mass creates gyroscopic forces that keep the bullets length axis resistant to the destabilizing overturning torque of the CP being in front of the CG, the effect of gravity on a projectile in flight is often referred to as projectile drop or bullet drop. It is important to understand the effect of gravity when zeroing the sighting components of a gun, to plan for projectile drop and compensate properly, one must understand parabolic shaped trajectories. In order for a projectile to impact any distant target, the barrel must be inclined to an elevation angle relative to the target. This is due to the fact that the projectile will begin to respond to the effects of gravity the instant it is free from the constraints of the bore. The imaginary line down the axis of the bore and out to infinity is called the line of departure and is the line on which the projectile leaves the barrel. Due to the effects of gravity a projectile can never impact a target higher than the line of departure, when a positively inclined projectile travels downrange, it arcs below the line of departure as it is being deflected off its initial path by gravity. Projectile/Bullet drop is defined as the distance of the projectile below the line of departure from the bore. Even when the line of departure is tilted upward or downward, projectile drop does not describe the actual trajectory of the projectile
11.
United States Army
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The United States Armed Forces are the federal armed forces of the United States. They consist of the Army, Marine Corps, Navy, Air Force, from the time of its inception, the military played a decisive role in the history of the United States. A sense of unity and identity was forged as a result of victory in the First Barbary War. Even so, the Founders were suspicious of a permanent military force and it played an important role in the American Civil War, where leading generals on both sides were picked from members of the United States military. Not until the outbreak of World War II did a standing army become officially established. The National Security Act of 1947, adopted following World War II and during the Cold Wars onset, the U. S. military is one of the largest militaries in terms of number of personnel. It draws its personnel from a pool of paid volunteers. As of 2016, the United States spends about $580.3 billion annually to fund its military forces, put together, the United States constitutes roughly 40 percent of the worlds military expenditures. For the period 2010–14, the Stockholm International Peace Research Institute found that the United States was the worlds largest exporter of major arms, the United States was also the worlds eighth largest importer of major weapons for the same period. The history of the U. S. military dates to 1775 and these forces demobilized in 1784 after the Treaty of Paris ended the War for Independence. All three services trace their origins to the founding of the Continental Army, the Continental Navy, the United States President is the U. S. militarys commander-in-chief. Rising tensions at various times with Britain and France and the ensuing Quasi-War and War of 1812 quickened the development of the U. S. Navy, the reserve branches formed a military strategic reserve during the Cold War, to be called into service in case of war. Time magazines Mark Thompson has suggested that with the War on Terror, Command over the armed forces is established in the United States Constitution. The sole power of command is vested in the President by Article II as Commander-in-Chief, the Constitution also allows for the creation of executive Departments headed principal officers whose opinion the President can require. This allowance in the Constitution formed the basis for creation of the Department of Defense in 1947 by the National Security Act, the Defense Department is headed by the Secretary of Defense, who is a civilian and member of the Cabinet. The Defense Secretary is second in the chain of command, just below the President. Together, the President and the Secretary of Defense comprise the National Command Authority, to coordinate military strategy with political affairs, the President has a National Security Council headed by the National Security Advisor. The collective body has only power to the President
12.
Thermonuclear weapon
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A thermonuclear weapon is a nuclear weapon that uses the energy from a primary nuclear fission reaction to compress and ignite a secondary nuclear fusion reaction. The result is greatly increased power when compared to single-stage fission weapons. It is colloquially referred to as a bomb or an H-bomb because it employs the fusion of isotopes of hydrogen. The first full scale thermonuclear test was carried out by the United States in 1952, similar devices were developed by the Soviet Union, United Kingdom, China, and France. The radiation implosion mechanism is an engine that exploits the temperature difference between the secondary stages hot, surrounding radiation channel and its relatively cool interior. This temperature difference is maintained by a massive heat barrier called the pusher. If made of uranium, as is almost always the case, it can capture neutrons produced by the reaction and undergo fission itself. In many Teller–Ulam weapons, fission of the pusher dominates the explosion, detailed knowledge of fission and fusion weapons is classified to some degree in virtually every industrialized nation. Born secret is rarely invoked for cases of private speculation, in a small number of prior cases, the U. S. government has attempted to censor weapons information in the public press, with limited success. According to the New York Times, physicist Kenneth Ford defied government orders to remove classified information from his new book, Building the H Bomb, the state of public knowledge about the Teller–Ulam design has been mostly shaped from a few specific incidents outlined in a section below. At a bare minimum, this implies a primary section consists of an implosion-type fission bomb. The energy released by the primary compresses the secondary through a process called radiation implosion, at which point it is heated, surrounding the other components is a hohlraum or radiation case, a container that traps the first stage or primarys energy inside temporarily. The outside of this case, which is also normally the outside casing of the bomb, is the only direct visual evidence publicly available of any thermonuclear bomb components configuration. Numerous photographs of various thermonuclear bomb exteriors have been declassified, generally, a research program with the capacity to create a thermonuclear bomb has already mastered the ability to engineer boosted fission. The secondary is usually shown as a column of fusion fuel, around the column is first a pusher-tamper, a heavy layer of uranium-238 or lead that serves to help compress the fusion fuel. Inside this is the fuel itself, usually a form of lithium deuteride. This dry fuel, when bombarded by neutrons, produces tritium, inside the layer of fuel is the spark plug, a hollow column of fissile material that, when compressed, can itself undergo nuclear fission. The tertiary, if one is present, would be set below the secondary, separating the secondary from the primary is the interstage
13.
Moore School of Electrical Engineering
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The Moore School of Electrical Engineering at the University of Pennsylvania came into existence as a result of an endowment from Alfred Fitler Moore on June 4,1923. It was granted to Penns School of Electrical Engineering, located in the Towne Building, the first dean of the Moore School was Harold Pender. The first computer course was given at the Moore School in Summer 1946, Moore School faculty John Mauchly and J. Presper Eckert founded the first computer company, which produced the UNIVAC computer. The Moore School has been integrated into Penns School of Engineering and it no longer exists as a separate entity, however, the three-story structure itself still stands and is known on campus as the Moore School Building. Originally constructed in 1921 as a building by Erskin & Morris, it was renovated in 1926 by Paul Philippe Cret. A complete history for all of Penn Engineering, including the Moore School
14.
Herman Goldstine
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Herman Heine Goldstine was a mathematician and computer scientist, who was one of the original developers of ENIAC, the first of the modern electronic digital computers. Herman Heine Goldstine was born in Chicago in 1913 to Jewish parents and he attended the University of Chicago, where he joined the Phi Beta Kappa fraternity, and graduated with a degree in Mathematics in 1933, a masters degree in 1934, and a PhD in 1936. For three years he was an assistant under Gilbert Ames Bliss, an authority on the mathematical theory of external ballistics. In 1939 Goldstine began a career at the University of Michigan, until the United States entry into World War II. In 1941 he married Adele Katz, who was an ENIAC programmer and he had a daughter and a son with Adele, who died in 1964. Two years later he married secondly Ellen Watson, Goldstine died on June 16,2004 at his home in Bryn Mawr, Pennsylvania, after a long struggle with Parkinsons disease. His death was announced by the Thomas J. Watson Research Center in Yorktown Heights, New York, as a result of the United States entering World War II, Goldstine left the University of Michigan where he was a professor in July,1942 to enlist in the Army. He was commissioned a lieutenant and worked as an ordnance mathematician calculating firing tables at the Ballistic Research Laboratory at Aberdeen Proving Ground, Maryland, the firing tables were used in battle to find the appropriate elevation and azimuth for aiming artillery, which had a range of several miles. The firing table calculations were accomplished by one hundred women operating mechanical desk calculators. Each combination of gun, round and geographical region required a set of firing tables. It took about 750 calculations to compute a trajectory and each table had about 3,000 trajectories. It took human computer at least 7 hours to calculate one trajectory, Mauchly wrote a proposal and in June 1943 he and Goldstine secured funding from the Army for the project. The ENIAC was built in 30 months with 200,000 man hours, the ENIAC was huge, measuring 30 by 60 feet and weighing 30 tons with 18,000 vacuum tubes. The device could only store 20 numbers and took days to program and it was completed in late 1945 as World War II was coming to an end. In spite of disappointment that ENIAC had not contributed to the war effort, prior even to the ENIACs completion, the Army procured a second contract from the Moore School to build a successor machine known as the EDVAC. Goldstine, Mauchly, J. Presper Eckert and Arthur Burks began to study the development of the new machine in the hopes of correcting the deficiencies of the ENIAC. Unknown to Goldstine, Neumann was then working on the Manhattan Project, the calculations needed for this project were also daunting. As a result of his conversations with Goldstine, Neumann joined the study group, Neumann intended this to be a memo to the study group, but Goldstine typed it up into a 101-page document that named Neumann as the sole author
15.
Arthur Burks
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Decades later, Burks and his wife Alice Burks outlined their case for the subject matter of the ENIAC having been derived from John Vincent Atanasoff. Burks was also for several decades a faculty member at the University of Michigan in Ann Arbor, Burks was born in Duluth, Minnesota. Both Burks and Mauchly sought and obtained teaching positions at the Moore School the following fall, when Mauchly and Eckerts proposed concept for an electronic digital computer was funded by the U. S. Armys Ballistics Research Laboratory in June 1943, Burks was added to the design team. Among his principal contributions to the project was the design of the multiplier unit. In April 1945, with John Grist Brainerd, Burks was charged with writing the reports on the ENIAC for publication. Also during 1945 Burks assisted with the logical design of the EDVAC in meetings attended by Mauchly, Eckert, John von Neumann. Burks also took a position as a philosophy instructor at Swarthmore College during 1945-1946. On March 8,1946 Burks accepted an offer by von Neumann to join the project at the Institute for Advanced Study in Princeton, New Jersey. During his time at the IAS, Burks worked to expand von Neumanns theory of automata and he declined a position heading up a different universitys computing center, citing his primary interest as the purely theoretical aspects of computing machines. He was awarded the Louis E. Levi Medal in 1956, Burks doctoral students include John Holland, who in 1959 was the first student to receive a Ph. D. in computer science from Michigan, and possibly the first in the world. Burks served as president of the Charles S. Peirce Society in 1954-1955 and he edited the final two volumes, published 1958, of the Collected Papers of Charles Sanders Peirce and, over the years, wrote published articles on Peirce. In the 1960s he was presented with the opportunity to acquire four units of the original ENIAC and he ran the units through a car wash before restoring them and donating them to the University of Michigan. They are currently on display in the entryway of the Computer Science Building, in 1964 Burks was approached by attorney Sy Yuter and asked to join T. Kite Sharpless and Robert F. In the 1970s Burks began meeting with Bob Axelrod, Michael Cohen, the BACH group continues to meet irregularly as part of the University of Michigans Center for the Study of Complex Systems. In the 1970s and 1980s Burks, working with his wife Alice, authored a number of articles on the ENIAC, in 1990, Burks donated a portion of his papers to the universitys Bentley Historical Library, where they are accessible to researchers. Burks died May 14,2008 in an Ann Arbor, Michigan nursing home from Alzheimers disease, Burks, Arthur W. and Wright, Jesse Bowdle, Theory of Logical Nets. Amazon says, published by Burroughs Adding Machine Co, google Books says, published by University of Michigan Engineering Research Institute,52 pages. Burks, Arthur W. and Copi, Irving M, the logic of fixed and growing automata, Engineering Research Institute, University of Michigan,34 pages
16.
Harry Huskey
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Harry Douglas Huskey is an American computer designer pioneer. Huskey was born in the Smoky Mountains region of North Carolina and he received his Bachelors degree at the University of Idaho. He gained his Masters and then his PhD in 1943 from the Ohio State University on Contributions to the Problem of Geocze, Huskey taught mathematics at the University of Pennsylvania and then worked part-time on the early ENIAC computer in 1945. He visited the National Physical Laboratory in the United Kingdom for a year and worked on the Pilot ACE computer with Alan Turing and he was also involved with the EDVAC and SEAC computer projects. Huskey designed and managed the construction of the Standards Western Automatic Computer at the National Bureau of Standards in Los Angeles and he also designed the G15 computer for Bendix Aviation Corporation, which could perhaps be considered as the first personal computer in the world. He had one at his home that is now in the Smithsonian Institution in Washington, after five years at the National Bureau of Standards, Huskey joined the faculty of the University of California, Berkeley in 1954 and then University of California, Santa Cruz from 1966. While at Berkeley, he supervised the research of pioneering programming language designer Niklaus Wirth, during 1963-1964 Prof. Huskey participated in establishing the Computer Center at IIT Kanpur and convened a meeting there with many pioneers of computing technology. Participants included Forman Acton of Princeton University, Robert Archer of Case Institute of Technology, barton of CDC, Australia, S. Prof. Huskey is now Professor Emeritus at the University of California, after his retirement at the age of 70 in 1986. In 1994 he was inducted as a Fellow of the Association for Computing Machinery, Huskey married Velma Roeth and had four children. In 1994, he married Nancy Grindstaff and he lives in Santa Cruz, California. Huskey appeared with a junk dealer as the pair of contestants in the 10 May 1950 episode of Groucho Marxs radio show You Bet Your Life. He was described as the designer of an electronic brain and they selected the state category and missed the final question when they failed to identify Iowa as the state North of Missouri. Huskey, H. D. Harry D. Huskey, His Story, the ACE Test Assembly, the Pilot ACE, the Big ACE, and the Bendix G15. In Copeland, B. J. Alan Turings Automatic Computing Engine, chapter 13, the state of the art in electronic digital computing in Britain and the United States. In Copeland, B. J. Alan Turings Automatic Computing Engine, chapter 23, Harry D. Huskey at DBLP Bibliography Server
17.
Decimal
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This article aims to be an accessible introduction. For the mathematical definition, see Decimal representation, the decimal numeral system has ten as its base, which, in decimal, is written 10, as is the base in every positional numeral system. It is the base most widely used by modern civilizations. Decimal fractions have terminating decimal representations and other fractions have repeating decimal representations, Decimal notation is the writing of numbers in a base-ten numeral system. Examples are Brahmi numerals, Greek numerals, Hebrew numerals, Roman numerals, Roman numerals have symbols for the decimal powers and secondary symbols for half these values. Brahmi numerals have symbols for the nine numbers 1–9, the nine decades 10–90, plus a symbol for 100, Chinese numerals have symbols for 1–9, and additional symbols for powers of ten, which in modern usage reach 1072. Positional decimal systems include a zero and use symbols for the ten values to represent any number, positional notation uses positions for each power of ten, units, tens, hundreds, thousands, etc. The position of each digit within a number denotes the multiplier multiplied with that position has a value ten times that of the position to its right. There were at least two independent sources of positional decimal systems in ancient civilization, the Chinese counting rod system. Ten is the number which is the count of fingers and thumbs on both hands, the English word digit as well as its translation in many languages is also the anatomical term for fingers and toes. In English, decimal means tenth, decimate means reduce by a tenth, however, the symbols used in different areas are not identical, for instance, Western Arabic numerals differ from the forms used by other Arab cultures. A decimal fraction is a fraction the denominator of which is a power of ten. g, Decimal fractions 8/10, 1489/100, 24/100000, and 58900/10000 are expressed in decimal notation as 0.8,14.89,0.00024,5.8900 respectively. In English-speaking, some Latin American and many Asian countries, a period or raised period is used as the separator, in many other countries, particularly in Europe. The integer part, or integral part of a number is the part to the left of the decimal separator. The part from the separator to the right is the fractional part. It is usual for a number that consists only of a fractional part to have a leading zero in its notation. Any rational number with a denominator whose only prime factors are 2 and/or 5 may be expressed as a decimal fraction and has a finite decimal expansion. 1/2 =0.5 1/20 =0.05 1/5 =0.2 1/50 =0.02 1/4 =0.25 1/40 =0.025 1/25 =0.04 1/8 =0.125 1/125 =0.008 1/10 =0
18.
Vacuum tube
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In electronics, a vacuum tube, an electron tube, or just a tube, or valve, is a device that controls electric current between electrodes in an evacuated container. Vacuum tubes mostly rely on thermionic emission of electrons from a hot filament or a cathode heated by the filament and this type is called a thermionic tube or thermionic valve. A phototube, however, achieves electron emission through the photoelectric effect, the simplest vacuum tube, the diode, contains only a heater, a heated electron-emitting cathode, and a plate. Current can only flow in one direction through the device between the two electrodes, as electrons emitted by the travel through the tube and are collected by the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grid or grids, Tubes with grids can be used for many purposes, including amplification, rectification, switching, oscillation, and display. In the 1940s the invention of devices made it possible to produce solid-state devices, which are smaller, more efficient, more reliable, more durable. Hence, from the mid-1950s solid-state devices such as transistors gradually replaced tubes, the cathode-ray tube remained the basis for televisions and video monitors until superseded in the 21st century. However, there are still a few applications for which tubes are preferred to semiconductors, for example, the used in microwave ovens. One classification of vacuum tubes is by the number of active electrodes, a device with two active elements is a diode, usually used for rectification. Devices with three elements are used for amplification and switching. Additional electrodes create tetrodes, pentodes, and so forth, which have additional functions made possible by the additional controllable electrodes. X-ray tubes are vacuum tubes. Phototubes and photomultipliers rely on electron flow through a vacuum, though in those cases electron emission from the cathode depends on energy from photons rather than thermionic emission, since these sorts of vacuum tubes have functions other than electronic amplification and rectification they are described in their own articles. A vacuum tube consists of two or more electrodes in a vacuum inside an airtight enclosure, most tubes have glass envelopes, though ceramic and metal envelopes have been used. The electrodes are attached to leads which pass through the envelope via an airtight seal, Tubes were a frequent cause of failure in electronic equipment, and consumers were expected to be able to replace tubes themselves. In addition to the terminals, some tubes had an electrode terminating at a top cap. The principal reason for doing this was to avoid leakage resistance through the tube base, the bases were commonly made with phenolic insulation which performs poorly as an insulator in humid conditions. There was even a design that had two top cap connections
19.
Diode
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In electronics, a diode is a two-terminal electronic component that conducts primarily in one direction, it has low resistance to the current in one direction, and high resistance in the other. A semiconductor diode, the most common today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. A vacuum tube diode has two electrodes, a plate and a heated cathode, semiconductor diodes were the first semiconductor electronic devices. The discovery of crystals rectifying abilities was made by German physicist Ferdinand Braun in 1874, the first semiconductor diodes, called cats whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today, most diodes are made of silicon, but other such as selenium and germanium are sometimes used. The most common function of a diode is to allow a current to pass in one direction. Thus, the diode can be viewed as a version of a check valve. However, diodes can have complicated behavior than this simple on–off action. Semiconductor diodes begin conducting electricity only if a threshold voltage or cut-in voltage is present in the forward direction. The voltage drop across a forward-biased diode varies only a little with the current, and is a function of temperature, a semiconductor diodes current–voltage characteristic can be tailored by selecting the semiconductor materials and the doping impurities introduced into the materials during manufacture. These techniques are used to create special-purpose diodes that perform different functions. Tunnel, Gunn and IMPATT diodes exhibit negative resistance, which is useful in microwave, Diodes, both vacuum and semiconductor, can be used as shot-noise generators. Thermionic diodes and solid state diodes were developed separately, at approximately the time, in the early 1900s. Until the 1950s vacuum tube diodes were used frequently in radios because the early point-contact type semiconductor diodes were less stable. In 1873, Frederick Guthrie discovered the principle of operation of thermionic diodes. Guthrie discovered that a positively charged electroscope could be discharged by bringing a piece of white-hot metal close to it. The same did not apply to a negatively charged electroscope, indicating that the current flow was possible in one direction. Thomas Edison independently rediscovered the principle on February 13,1880, at the time, Edison was investigating why the filaments of his carbon-filament light bulbs nearly always burned out at the positive-connected end
20.
Relay
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A relay is an electrically operated switch. Many relays use an electromagnet to operate a switch, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a separate low-power signal, the first relays were used in long distance telegraph circuits as amplifiers, they repeated the signal coming in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations, a type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a device to perform switching. Magnetic latching relays require one pulse of power to move their contacts in one direction. Repeated pulses from the same input have no effect, magnetic latching relays are useful in applications where interrupted power should not be able to transition the contacts. Magnetic latching relays can have single or dual coils. On a single device, the relay will operate in one direction when power is applied with one polarity. On a dual coil device, when polarized voltage is applied to the coil the contacts will transition. AC controlled magnetic latch relays have single coils that employ steering diodes to differentiate between operate and reset commands, american scientist Joseph Henry is often claimed to have invented a relay in 1835 in order to improve his version of the electrical telegraph, developed earlier in 1831. However, there is little in the way of documentation to suggest he had made the discovery prior to 1837. It is claimed that English inventor Edward Davy certainly invented the electric relay in his electric telegraph c.1835, a simple device, which is now called a relay, was included in the original 1840 telegraph patent of Samuel Morse. The mechanism described acted as an amplifier, repeating the telegraph signal. This overcame the problem of limited range of earlier telegraphy schemes, the word relay appears in the context of electromagnetic operations from 1860. The armature is hinged to the yoke and mechanically linked to one or more sets of moving contacts, the armature is held in place by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the relay pictured is closed, and the set is open. Other relays may have more or fewer sets of contacts depending on their function, the relay in the picture also has a wire connecting the armature to the yoke
21.
Resistor
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A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of power as heat may be used as part of motor controls, in power distribution systems. Fixed resistors have resistances that only slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements, or as sensing devices for heat, light, humidity, force, Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds, Resistors are also implemented within integrated circuits. The electrical function of a resistor is specified by its resistance, the nominal value of the resistance falls within the manufacturing tolerance, indicated on the component. Two typical schematic diagram symbols are as follows, The notation to state a resistors value in a circuit diagram varies, one common scheme is the letter and digit code for resistance values following IEC60062. It avoids using a separator and replaces the decimal separator with a letter loosely associated with SI prefixes corresponding with the parts resistance. For example, 8K2 as part marking code, in a diagram or in a bill of materials indicates a resistor value of 8.2 kΩ. Additional zeros imply a tighter tolerance, for example 15M0 for three significant digits, when the value can be expressed without the need for a prefix, an R is used instead of the decimal separator. For example, 1R2 indicates 1.2 Ω, and 18R indicates 18 Ω, for example, if a 300 ohm resistor is attached across the terminals of a 12 volt battery, then a current of 12 /300 =0.04 amperes flows through that resistor. Practical resistors also have some inductance and capacitance which affect the relation between voltage and current in alternating current circuits, the ohm is the SI unit of electrical resistance, named after Georg Simon Ohm. An ohm is equivalent to a volt per ampere, since resistors are specified and manufactured over a very large range of values, the derived units of milliohm, kilohm, and megohm are also in common usage. The total resistance of resistors connected in series is the sum of their resistance values. R e q = R1 + R2 + ⋯ + R n, the total resistance of resistors connected in parallel is the reciprocal of the sum of the reciprocals of the individual resistors. 1 R e q =1 R1 +1 R2 + ⋯ +1 R n. For example, a 10 ohm resistor connected in parallel with a 5 ohm resistor, a resistor network that is a combination of parallel and series connections can be broken up into smaller parts that are either one or the other
22.
Capacitor
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A capacitor is a passive two-terminal electrical component that stores electrical energy in an electric field. The effect of a capacitor is known as capacitance, a capacitor was therefore historically first known as an electric condenser. The physical form and construction of practical capacitors vary widely and many types are in common use. Most capacitors contain at least two electrical conductors often in the form of plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, the nonconducting dielectric acts to increase the capacitors charge capacity. Materials commonly used as dielectrics include glass, ceramic, plastic film, paper, mica, Capacitors are widely used as parts of electrical circuits in many common electrical devices. Unlike a resistor, a capacitor does not dissipate energy. No current actually flows through the dielectric, instead, the effect is a displacement of charges through the source circuit, if the condition is maintained sufficiently long, this displacement current through the battery ceases. However, if a voltage is applied across the leads of the capacitor. Capacitance is defined as the ratio of the charge on each conductor to the potential difference between them. The unit of capacitance in the International System of Units is the farad, capacitance values of typical capacitors for use in general electronics range from about 1 pF to about 1 mF. The capacitance of a capacitor is proportional to the area of the plates. In practice, the dielectric between the plates passes a small amount of leakage current and it has an electric field strength limit, known as the breakdown voltage. The conductors and leads introduce an undesired inductance and resistance, Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass. In analog filter networks, they smooth the output of power supplies, in resonant circuits they tune radios to particular frequencies. In electric power systems, they stabilize voltage and power flow. The property of energy storage in capacitors was exploited as dynamic memory in digital computers. Von Kleists hand and the water acted as conductors, and the jar as a dielectric, von Kleist found that touching the wire resulted in a powerful spark, much more painful than that obtained from an electrostatic machine
23.
Solder
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Solder is a fusible metal alloy used to create a permanent bond between metal workpieces. The word solder comes from the Middle English word soudur, via Old French solduree and soulder, from the Latin solidare, meaning to make solid. In fact, solder must be melted in order to adhere to and connect the pieces together, whenever possible, the solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder that is intended for use in making connections between electronic components also usually has favorable electrical characteristics. Soft solder typically has a melting point range of 90 to 450 °C, and is used in electronics, plumbing. Manual soldering uses an iron or soldering gun. Alloys that melt between 180 and 190 °C are the most commonly used, soldering performed using alloys with a melting point above 450 °C is called hard soldering, silver soldering, or brazing. In specific proportions, some alloys can become eutectic — that is, non-eutectic alloys have markedly different solidus and liquidus temperatures, and within that range they exist as a paste of solid particles in a melt of the lower-melting phase. In electrical work, if the joint is disturbed in the pasty state before it has solidified totally, for electrical and electronics work, solder wire is available in a range of thicknesses for hand-soldering, and with cores containing flux. It is also available as a paste or as a preformed foil shaped to match the workpiece, alloys of lead and tin were commonly used in the past, and are still available, they are particularly convenient for hand-soldering. Lead-free solders have been increasing in use due to regulatory requirements plus the health and they are almost exclusively used today in consumer electronics. Plumbers often use bars of solder, much thicker than the used for electrical applications. Jewelers often use solder in thin sheets, which cut into snippets. In the US, manufacturers may receive tax benefits by reducing the use of lead-based solder, lead-free solders in commercial use may contain tin, copper, silver, bismuth, indium, zinc, antimony, and traces of other metals. Most lead-free replacements for conventional 60/40 and 63/37 Sn-Pb solder have melting points from 5 to 20 °C higher and it may be desirable to use minor modification of the solder pots used in wave-soldering, to reduce maintenance cost due to increased tin-scavenging of high-tin solder. Lead-free solder may be desirable for critical applications, such as aerospace and medical projects. Tin-Silver-Copper solders are used by two-thirds of Japanese manufacturers for reflow and wave soldering, tin-based solders readily dissolve gold, forming brittle intermetallics, for Sn-Pb alloys the critical concentration of gold to embrittle the joint is about 4%. Indium-rich solders are more suitable for soldering thicker gold layer as the rate of gold in indium is much slower
24.
Punched card input/output
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A computer punched card reader or just computer card reader is a computer input device used to read executable computer programs and data from punched cards under computer control. A computer card punch is an output device that punches holes in cards under computer control. Sometimes computer card readers were combined with card punches and. Most early computers, such as the ENIAC, and the IBM NORC, card readers and punches, either connected to computers or in off-line card to/from magnetic tape configurations, were ubiquitous through the mid-1970s. Punched cards had been in use since the 1890s, their technology was mature, card readers and punches developed for punched card machines were readily adaptable for computer use. Businesses were familiar with storing data on punched cards and keypunch machines were widely employed, punched cards were a better fit than other 1950s technologies, such as magnetic tape, for some computer applications as individual cards could easily be updated without having to access a computer. The standard measure of speed is cards per minute, abbreviated CPM, card reader models vary from 300 to around 2000 CPM. If all columns of an 80 column card encode information this translates to approximately 2500 characters per second, cards may be read using mechanical brushes that make an electrical contact for a hole, and no contact if no punch, or photoelectric sensors that function similarly. Timing relates the signals to the position on the card, cards may be read serially, column by column, or in parallel, row by row. Card punches necessarily run more slowly to allow for the action of punching. Some card devices offer the ability to interpret, or print a line on the card displaying the data that is punched, typically this slows down the punch operation. Many punches read the card just punched and compare its actual contents to the data punched. Some devices allow data to be read from a card and additional information to be punched into the same card, readers and punches include a hopper for input cards and one or more stackers for cards read or punched. A function called stacker select allows the computer to choose which stacker a card just read or punched will be placed into. CDC405 — CDC6000 series card reader CDC415 — CDC6000 series card punch Documation Inc, for example, the IBM711 card reader used with the 704/709/7090/7094 series scientific computers treated every row as two 36-bit words, ignoring 8 columns. Sometimes the ignored columns were used to contain a number for each card. An alternative format, used by the IBM 704s IBM714 native card reader, is referred to as Column Binary or Chinese Binary, later computers, such as the IBM1130 or System/360, used every column. The IBM 1401s card reader could be used in Column Binary mode, however, most of the older card punches were not intended to punch more than 3 holes in a column
25.
IBM
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International Business Machines Corporation is an American multinational technology company headquartered in Armonk, New York, United States, with operations in over 170 countries. The company originated in 1911 as the Computing-Tabulating-Recording Company and was renamed International Business Machines in 1924, IBM manufactures and markets computer hardware, middleware and software, and offers hosting and consulting services in areas ranging from mainframe computers to nanotechnology. IBM is also a research organization, holding the record for most patents generated by a business for 24 consecutive years. IBM has continually shifted its business mix by exiting commoditizing markets and focusing on higher-value, also in 2014, IBM announced that it would go fabless, continuing to design semiconductors, but offloading manufacturing to GlobalFoundries. Nicknamed Big Blue, IBM is one of 30 companies included in the Dow Jones Industrial Average and one of the worlds largest employers, with nearly 380,000 employees. Known as IBMers, IBM employees have been awarded five Nobel Prizes, six Turing Awards, ten National Medals of Technology, in the 1880s, technologies emerged that would ultimately form the core of what would become International Business Machines. On June 16,1911, their four companies were amalgamated in New York State by Charles Ranlett Flint forming a fifth company, the Computing-Tabulating-Recording Company based in Endicott, New York. The five companies had 1,300 employees and offices and plants in Endicott and Binghamton, New York, Dayton, Ohio, Detroit, Michigan, Washington, D. C. and Toronto. They manufactured machinery for sale and lease, ranging from commercial scales and industrial time recorders, meat and cheese slicers, to tabulators and punched cards. Thomas J. Watson, Sr. fired from the National Cash Register Company by John Henry Patterson, called on Flint and, Watson joined CTR as General Manager then,11 months later, was made President when court cases relating to his time at NCR were resolved. Having learned Pattersons pioneering business practices, Watson proceeded to put the stamp of NCR onto CTRs companies and his favorite slogan, THINK, became a mantra for each companys employees. During Watsons first four years, revenues more than doubled to $9 million, Watson had never liked the clumsy hyphenated title of the CTR and in 1924 chose to replace it with the more expansive title International Business Machines. By 1933 most of the subsidiaries had been merged into one company, in 1937, IBMs tabulating equipment enabled organizations to process unprecedented amounts of data, its clients including the U. S. During the Second World War the company produced small arms for the American war effort, in 1949, Thomas Watson, Sr. created IBM World Trade Corporation, a subsidiary of IBM focused on foreign operations. In 1952, he stepped down after almost 40 years at the company helm, in 1957, the FORTRAN scientific programming language was developed. In 1961, IBM developed the SABRE reservation system for American Airlines, in 1963, IBM employees and computers helped NASA track the orbital flight of the Mercury astronauts. A year later it moved its headquarters from New York City to Armonk. The latter half of the 1960s saw IBM continue its support of space exploration, on April 7,1964, IBM announced the first computer system family, the IBM System/360
26.
Tabulating machine
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The tabulating machine was an electromechanical machine designed to assist in summarizing information stored on punched cards. Invented by Herman Hollerith, the machine was developed to process data for the 1890 U. S. Census. Later models were used for business applications such as accounting. It spawned a class of machines, known as unit record equipment, the term Super Computing was used by the New York World newspaper in 1931 to refer to a large custom-built tabulator that IBM made for Columbia University. The 1880 census had taken eight years to process, constitution mandates a census every ten years to apportion both congressional representatives and direct taxes among the states, a larger staff or faster method was required. Prior uses of machine readable media had been for lists of instructions to drive programmed machines such as Jacquard looms, after some initial trials with paper tape, he settled on punched cards. Hollerith used punched cards with holes,12 rows and 24 columns. His tabulator used electromechanical relays to increment mechanical counters, a set of spring-loaded wires were suspended over the card reader. The card sat over pools of mercury, pools corresponding to the hole positions in the card. This arrangement allowed a count up to 10,000, during a given tabulating run, counters could be assigned a specific hole or, using relay logic, a combination of holes, e. g. to count married females. If the card was to be sorted a compartment lid of the box would open for storage of the card. Holleriths method was used for the 1890 census, clerks used keypunches to punch holes in the cards entering age, state of residence, gender, and other information from the returns. The advantages of the technology were immediately apparent for accounting and tracking inventory, Hollerith started his own business as The Hollerith Electric Tabulating System, specializing in punched card data processing equipment. In 1896 he incorporated the Tabulating Machine Company, in that year he introduced the Hollerith Integrating Tabulator, which could add numbers coded on punched cards, not just count the number of holes. Punched cards were still read using the pins and mercury pool reader. 1900 saw the Hollerith Automatic Feed Tabulator used in that years U. S. census, a control panel was incorporated in the 1906 Type 1. In 1911, four corporations, including Holleriths firm, were amalgamated to form a fifth company, the Powers Accounting Machine Company was formed that same year and, like Hollerith, with machines first developed at the Census Bureau. In 1919 the first Bull tabulator prototype was developed, tabulators that could print, and with removable control panels, appeared in the 1920s
27.
Magnetic-core memory
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Magnetic-core memory was the predominant form of random-access computer memory for 20 years between about 1955 and 1975. Such memory is often just called core memory, or, informally, Core uses tiny magnetic toroids, the cores, through which wires are threaded to write and read information. Each core represents one bit of information, the cores can be magnetized in two different ways and the bit stored in a core is zero or one depending on that cores magnetization direction. The process of reading the core causes the core to be reset to a zero, when not being read or written, the cores maintain the last value they had, even when power is turned off. Using smaller cores and wires, the density of core slowly increased. However, reaching this density required extremely careful manufacture, almost always carried out by hand in spite of repeated efforts to automate the process. The cost declined over this period from about $1 per bit to about 1 cent per bit, the introduction of the first semiconductor memory SRAM chips in the late 1960s began to erode the core market. The first successful DRAM, the Intel 1103 which arrived in quantity in 1972 at 1 cent per bit, improvements in semiconductor manufacturing led to rapid increases in storage and decreases in price that drove core from the market by around 1974. Although core memory is obsolete, any computer memory is still occasionally called core, in particular, the basic concept of using the square hysteresis loop of certain magnetic materials as a storage or switching device was known from the earliest days of computer development. Much of this knowledge had developed due to an understanding of transformers, the stable switching behavior was well known in the electrical engineering field, and its application in computer systems was immediate. For example, J. Presper Eckert and Jeffrey Chuan Chu had done some development work on the concept in 1945 at the Moore School during the ENIAC efforts. Frederick Viehe applied for patents on the use of transformers for building digital logic circuits in place of relay logic beginning in 1947. A patent on a fully developed core system was granted in 1947 and this development was little-known, however, and the mainstream development of core is normally associated with three independent teams. Substantial work in the field was carried out by the Shanghai-born American physicists An Wang and Way-Dong Woo, the name referred to the way that the magnetic field of the cores could be used to control the switching of current in electromechanical systems. Wang and Woo were working at Harvard Universitys Computation Laboratory at the time, Wang was able to patent the system on his own. The MIT Whirlwind computer required a fast memory system for real-time aircraft tracking use, at first, Williams tubes—a storage system based on cathode ray tubes—were used, but these devices were always temperamental and unreliable. William Papian of Project Whirlwind cited one of these efforts, Harvards Static Magnetic Delay Line, the first core memory of 32 x 32 x 16 bits was installed on Whirlwind in the summer of 1953. In April 2011, Forrester recalled, the Wang use of cores did not have any influence on my development of random-access memory, the Wang memory was expensive and complicated
28.
Ring counter
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A ring counter is a type of counter composed of a type of circular shift register. The output of the last shift register is fed to the input of the first register, for example, in a 4-register one-hot counter, with initial register values of 1000, the repeating pattern is,1000,0100,0010,0001,1000. Note that one of the registers must be pre-loaded with a 1 in order to operate properly. For example, in a 4-register counter, with initial values of 0000. The Johnson counter generates a Gray code, a code in which adjacent states differ by one bit. The circuit of an Overbeck counter is shown here, Ring counters are used in logic design to create complicated finite state machines. A binary counter will require a circuit which is substantially more complex than a ring counter. Additionally, the worst case propagation delay on a circuit will be proportional to the number of bits in the code. The propagation delay of a counter will be a constant regardless of the number of bits in the code. The complex combinational logic of an adder can create timing errors which may result in erratic hardware performance, last, ring counters with Hamming distance 2 allow the detection of single bit upsets that can occur in hazardous environments. The disadvantage of ring counters is that they are lower density codes, a binary counter can represent 2^N states, where N is the number of bits in the code, whereas an Overbeck counter can represent only N states and a Johnson counter can represent only 2N states. This may be an important consideration in hardware implementations where registers are more expensive than combinational logic, Counter Ring oscillator Linear feedback shift register File,4 Bit Ring Counter. svg File, Code Libaw-Craig. svg Crowe, John, Hayes-Gill, Barrie. Fundamentals of digital logic and microcomputer design, John Wiley and Sons,2005, somanathan Nair, Digital electronics and logic design, PHI Learning Pvt. Ltd. Shift Register Counters Ring Counters The Johnson Counter German Wikibooks
29.
Flip-flop (electronics)
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In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. A flip-flop is a bistable multivibrator, the circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the storage element in sequential logic. Flip-flops and latches are fundamental building blocks of electronics systems used in computers, communications. Flip-flops and latches are used as storage elements. A flip-flop stores a bit of data, one of its two states represents a one and the other represents a zero. Such data storage can be used for storage of state, when used in a finite-state machine, the output and next state depend not only on its current input, but also on its current state. It can also be used for counting of pulses, and for synchronizing variably-timed input signals to some reference timing signal, flip-flops can be either simple or clocked. Using this terminology, a latch is level-sensitive, whereas a flip-flop is edge-sensitive and that is, when a latch is enabled it becomes transparent, while a flip flops output only changes on a single type of clock edge. The first electronic flip-flop was invented in 1918 by the British physicists William Eccles and it was initially called the Eccles–Jordan trigger circuit and consisted of two active elements. Early flip-flops were known variously as trigger circuits or multivibrators, according to P. L. Lindley was at the time working at Hughes Aircraft under Eldred Nelson, who had coined the term JK for a flip-flop which changed states when both inputs were on. The other names were coined by Phister and they differ slightly from some of the definitions given below. Lindley explains that he heard the story of the JK flip-flop from Eldred Nelson, flip-flops in use at Hughes at the time were all of the type that came to be known as J-K. Flip-flops can be simple or clocked. The simple ones are described as latches, while the clocked ones are described as flip-flops. Clocked devices are designed for synchronous systems, such devices ignore their inputs except at the transition of a dedicated clock signal. Clocking causes the flip-flop either to change or to retain its output signal based upon the values of the signals at the transition. Some flip-flops change output on the edge of the clock
30.
Adding machine
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An adding machine was a class of mechanical calculator, usually specialized for bookkeeping calculations. In the United States, the earliest adding machines were built to read in dollars. Adding machines were ubiquitous office equipment until they were phased out in favor of calculators in the 1970s, the older adding machines were rarely seen in American office settings by the year 2000. However, they did not gain widespread use until Dorr E. Felt started manufacturing his comptometer, to add a new list of numbers and arrive at a total, the user was first required to ZERO the machine. Then, to add sets of numbers, the user was required to press numbered keys on a keyboard, which would remain depressed. The user would then pull the crank, which caused the numbers to be shown on the wheels. The rotary wheels now showed 3072, press the 4 key in the 3rd column from the right, the 4 key in the 2nd column from right, and the 9 key in the rightmost column. The rotary wheels now show a total of 3521 which. Keyboards typically did not have or need 0 keys, one simply did not press any key in the column containing a zero, trailing zeros, were there by default because when a machine was zeroed, all numbers visible on the rotary wheels were reset to zero. Subtraction was impossible, except by adding the complement of a number, multiplication was a simple process of keying in the numbers one or more columns to the left and repeating the addition process. For example, to multiply 34.72 by 102, key in 3472, pull crank, wheels now show 354144, or 3,541.44 A later adding machine, called the comptometer, did not require that a crank be pulled to add. Numbers were input simply by pressing keys, the machine was thus driven by finger power. Multiplication was similar to that on the machine, but users would form up their fingers over the keys to be pressed. Using the above example, four fingers would be used to press down twice on the 3,4,7 and 2 keys and that finger shape would then move left two columns and press once. Usually a small crank near the wheels would be used to zero them, some adding machines were electromechanical — an old-style mechanism, but driven by electric power. Some ten-key machines had input of numbers as on a modern calculator –30.72 was input as 3,0,7,2 and these machines could subtract as well as add. Some could multiply and divide, although including these operations made the more complex. Those that could multiply, used a form of the old adding machine multiplication method, using the previous example of multiplying 34.72 by 102, the amount was keyed in, then the 2 key in the multiplication key column was pressed
31.
Accumulator (computing)
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In a computers central processing unit, an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for use in the next operation. Access to main memory is slower than access to a register like the accumulator because the used for the large main memory is slower than that used for a register. Early electronic computer systems were often split into two groups, those with accumulators and those without, modern computer systems often have multiple general purpose registers that operate as accumulators, and the term is no longer as common as it once was. However, a number of special-purpose processors still use a single accumulator for their work, mathematical operations often take place in a stepwise fashion, using the results from one operation as the input to the next. In early computers the number of hours would likely be held on a punch card, once the multiplication is complete, the result needs to be placed somewhere. On a drum machine this would likely be back to the drum, and then the very next operation has to read that value back in, which introduces another considerable delay. Accumulators dramatically improve performance in systems like these by providing an area where the results of one operation can be fed to the next one for little or no performance penalty. In the example above, the weekly pay would be calculated and placed in the accumulator. This removes one save and one read operation from the sequence, almost all early computers were accumulator machines with only the high-performance supercomputers having multiple registers. Then as mainframe systems gave way to microcomputers, accumulator architectures were again popular with the MOS6502 being a notable example, many 8-bit microcontrollers that are still popular as of 2014, such as the PICmicro and 8051, are accumulator-based machines. Modern CPUs are typically 2-operand or 3-operand machines, the additional operands specify which one of many general purpose registers are used as the source and destination for calculations. These CPUs are not considered accumulator machines, the characteristic which distinguishes one register as being the accumulator of a computer architecture is that the accumulator would be used as an implicit operand for arithmetic instructions. The accumulator is not identified in the instruction by a number, it is implicit in the instruction. Some architectures use a particular register as an accumulator in some instructions, any system that uses a single memory to store the result of multiple operations can be considered an accumulator. J. Presper Eckert refers to even the earliest adding machines of Gottfried Leibniz, should be a parallel storage organ which can receive a number and add it to the one already in it, which is also able to clear its contents and which can store what it contains. We will call such an organ an Accumulator and it is quite conventional in principle in past and present computing machines of the most varied types, e. g. desk multipliers, standard IBM counters, more modern relay machines, the ENIAC. Tradition, for example, uses two instructions called load accumulator from register/memory and store accumulator to register/memory, knuths model has many other instructions as well
32.
Ten's complement
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In mathematics and computing, the method of complements is a technique used to subtract one number from another using only addition of positive numbers. This method was used in mechanical calculators and is still used in modern computers. The nines complement of a number is formed by replacing each digit with nine minus that digit, to subtract a decimal number y from another number x two methods may be used, In the first method the nines complement of x is added to y. Then the nines complement of the result obtained is formed to produce the desired result, in the second method the nines complement of y is added to x and one is added to the sum. The leading digit 1 of the result is then discarded, discarding the initial 1 is especially convenient on calculators or computers that use a fixed number of digits, there is nowhere for it to go so it is simply lost during the calculation. The nines complement plus one is known as the tens complement, the radix complement of an n digit number y in radix b is, by definition, b n − y. The radix complement is most easily obtained by adding 1 to the radix complement. Since is the digit b −1 repeated n times, the diminished radix complement of a number is found by complementing each digit with respect to b −1. The subtraction of y from x may be performed as follows, the diminished radix complement of this is the value x − y. Alternatively, adding the complement of y to x results in the value x + b n − y or x − y + b n. In the decimal numbering system, the complement is called the tens complement. In binary, the complement is called the twos complement. The naming of complements in other bases is similar, some people, notably Donald Knuth, recommend using the placement of the apostrophe to distinguish between the radix complement and the diminished radix complement. In this usage, the fours complement refers to the complement of a number in base four while fours complement is the diminished radix complement of a number in base 5. However, the distinction is not important when the radix is apparent, most writers use ones and nines complement, and many style manuals leave out the apostrophe, recommending ones and nines complement. The nines complement of a digit is the number that must be added to it to produce 9, the complement of 3 is 6, the complement of 7 is 2. To form the complement of a larger number, each digit is replaced by its nines complement. Consider the following problem,873 -218 We compute the nines complement of the minuend,873
33.
Double-precision floating-point format
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Double-precision floating-point format is a computer number format that occupies 8 bytes in computer memory and represents a wide, dynamic range of values by using a floating point. Double-precision floating-point format usually refers to binary64, as specified by the IEEE754 standard, in older computers, different floating-point formats of 8 bytes were used, e. g. GW-BASICs double-precision data type was the 64-bit MBF floating-point format. Double-precision binary floating-point is a commonly used format on PCs, due to its range over single-precision floating point, in spite of its performance. As with single-precision floating-point format, it lacks precision on integer numbers when compared with a format of the same size. It is commonly simply as double. The IEEE754 standard specifies a binary64 as having, Sign bit,1 bit Exponent,11 bits Significand precision,53 bits This gives 15–17 significant decimal digits precision. If an IEEE754 double precision is converted to a string with at least 17 significant digits and then converted back to double. The format is written with the significand having an implicit integer bit of value 1, with the 52 bits of the fraction significand appearing in the memory format, the total precision is therefore 53 bits. For the next range, from 253 to 254, everything is multiplied by 2, so the numbers are the even ones. Conversely, for the range from 251 to 252, the spacing is 0.5. The spacing as a fraction of the numbers in the range from 2n to 2n+1 is 2n−52, the maximum relative rounding error when rounding a number to the nearest representable one is therefore 2−53. The 11 bit width of the exponent allows the representation of numbers between 10−308 and 10308, with full 15–17 decimal digits precision, by compromising precision, the subnormal representation allows even smaller values up to about 5 × 10−324. The double-precision binary floating-point exponent is encoded using a representation, with the zero offset being 1023. All bit patterns are valid encoding, except for the above exceptions, the entire double-precision number is described by, sign ×2 exponent − exponent bias ×1. Fraction In the case of subnormals the double-precision number is described by, because there have been many floating point formats with no network standard representation for them, the XDR standard uses big-endian IEEE754 as its representation. It may therefore appear strange that the widespread IEEE754 floating point standard does not specify endianness, theoretically, this means that even standard IEEE floating point data written by one machine might not be readable by another. One area of computing where this is an issue is for parallel code running on GPUs. For example, when using NVIDIAs CUDA platform, on video cards designed for gaming, doubles are implemented in many programming languages in different ways such as the following
34.
Square root
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In mathematics, a square root of a number a is a number y such that y2 = a, in other words, a number y whose square is a. For example,4 and −4 are square roots of 16 because 42 =2 =16, every nonnegative real number a has a unique nonnegative square root, called the principal square root, which is denoted by √a, where √ is called the radical sign or radix. For example, the square root of 9 is 3, denoted √9 =3. The term whose root is being considered is known as the radicand, the radicand is the number or expression underneath the radical sign, in this example 9. Every positive number a has two roots, √a, which is positive, and −√a, which is negative. Together, these two roots are denoted ± √a, although the principal square root of a positive number is only one of its two square roots, the designation the square root is often used to refer to the principal square root. For positive a, the square root can also be written in exponent notation. Square roots of numbers can be discussed within the framework of complex numbers. In Ancient India, the knowledge of theoretical and applied aspects of square and square root was at least as old as the Sulba Sutras, a method for finding very good approximations to the square roots of 2 and 3 are given in the Baudhayana Sulba Sutra. Aryabhata in the Aryabhatiya, has given a method for finding the root of numbers having many digits. It was known to the ancient Greeks that square roots of positive numbers that are not perfect squares are always irrational numbers, numbers not expressible as a ratio of two integers. This is the theorem Euclid X,9 almost certainly due to Theaetetus dating back to circa 380 BC, the particular case √2 is assumed to date back earlier to the Pythagoreans and is traditionally attributed to Hippasus. Mahāvīra, a 9th-century Indian mathematician, was the first to state that square roots of negative numbers do not exist, a symbol for square roots, written as an elaborate R, was invented by Regiomontanus. An R was also used for Radix to indicate square roots in Gerolamo Cardanos Ars Magna, according to historian of mathematics D. E. Smith, Aryabhatas method for finding the root was first introduced in Europe by Cataneo in 1546. According to Jeffrey A. Oaks, Arabs used the letter jīm/ĝīm, the letter jīm resembles the present square root shape. Its usage goes as far as the end of the century in the works of the Moroccan mathematician Ibn al-Yasamin. The symbol √ for the root was first used in print in 1525 in Christoph Rudolffs Coss
35.
Tube socket
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Tube sockets are electrical sockets into which vacuum tubes can be plugged, holding them in place and providing terminals, which can be soldered into the circuit, for each of the pins. Sockets are designed to allow tubes to be plugged in in one orientation. They were used in all electronic equipment to allow tubes. In the day of radio and television it was common in the US for local drug stores to have vacuum tube testers. Throughout the tube era, as developed, sometimes differently in different parts of the world, many tube bases. Sockets are not universal, different tubes may fit mechanically into the same socket, tube sockets were typically mounted in holes on a sheet metal chassis and wires or other components were hand soldered to lugs on the underside of the socket. In the 1950s, printed circuit boards were introduced and tube sockets were developed whose contacts could be soldered directly to the printed wiring tracks. In the 1930s, tubes often had the connection to the grid brought out through a metal top cap on the top of the tube. This was connected by using a clip with an attached wire lead, an example would be the 6A7 pentagrid converter. In both cases this allowed the tubes output circuitry to be isolated from the circuit more effectively. The earliest tubes, like the Deforest Spherical Audion from c,1911, used the typical light bulb Edison socket for the heater, and flying leads for the other elements. Other tubes directly used flying leads for all of their contacts, like the Cunningham AudioTron from 1915, or the Deforest Oscillion. Type C6A xenon thyratrons, used in servos for the U. S. Navy Stable Element Mark 6, had a screw base and L-shaped stiff wires at the top for grid. Mating connectors were machined pairs of blocks with clamping screws. When tubes became widespread, and new electrodes were added. Specially designed bases were created to account for this need, however, as the world was suffering from World War I, and the new electronics technology was just emerging, designs were far from being standardized. Usually, each company had their own tubes and sockets, which were not interchangeable with tubes from other companies, by the early 1920s, this situation was finally changing, and several standard bases were created. Sometimes they relied on a bayonet on the side of the base, examples of these are the very common USA bases UX4, UV4, UY5 and UX6, and the European B5, B6, B7, B8, C7, G8A, etc
36.
6SN7
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6SN7 is a dual triode vacuum tube with an 8-pin octal base. The 6SN7 is basically two 6J5 triodes in one envelope, european designations include the 1942 ECC32, 13D2 and B65. The 6SN7 has a 6.3 V600 mA heater/filament, the 12-volt 300 mA filament equivalent is the 12SN7GT or 12SN7GTA. The 14N7 is the Loktal version of the 12SN7GT, there was also a comparatively rare 8V 8SN7 for 450 mA series-string TV sets) and 25 Volt/0.15 Amp heater version, 25SN7GT. The 6J5, first registered in June 1937, and 6J5GT were octal single triodes with identical characteristics to one half of a 6SN7. Other equivalents to the 6J5 include, VT-94, 6C2, 6J5M, 38565J, military versions, CV1933, 10E/11448 and CV1934, Loktal base version, 7A4 and they in turn were successors to the 1935 RCA 6C5 and 1938 6P5G. The 1954 6CG7 and 6FQ7 are electrically equivalent to the 6SN7, with 9-pin miniature base, the 1948 ECC40 with Rimlock base can also considered a successor to the 6SN7. The 6SN7 was used as an amplifier in the 1940-1955 period. The 6SN7 was one of the most important components of the first programmable computer, the ENIAC. The SAGE computer systems used hundreds of 5692s as flip-flops, with the advent of television the 6SN7 was well suited for use as a vertical-deflection amplifier. As screen sizes became larger, voltage and power headroom became insufficient, to address this, uprated versions with higher peak voltage and power ratings were introduced. The GE 6SN7GTA had anode dissipation uprated to 5.0 watts, the 1954 GE 6SN7GTB also had controlled heater warmup time, better for series heater strings. The 6SN7 is considered to be obsolete by the 1960s, replaced by the 12AU7, with the introduction of semiconductor electronics, vacuum tubes of all types ceased to be manufactured by the major producers. As of 2012, 6SN7s were manufactured in Russia and China under the old Soviet designator 6N8S
37.
6L6
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6L6 is the designator for a vacuum tube introduced by Radio Corporation of America in July 1936. At the time Philips had already developed and patented power pentode designs, the beam tetrode design of the 6L6 allowed RCA to circumvent Philips pentode patent. The 6L6 is a descendant of the Harries Valve developed by British engineer J. Owen Harries and this design also minimized interference of secondary emission electrons dislodged from the anode. The beam tetrode design was undertaken to avoid the patents which the giant Philips firm held on power pentodes in Europe. Because MOVs engineers did not feel the kinkless tetrode could be successfully mass-produced and this proved to be a poor business decision on MOVs part. RCA subsequently had success with the 6L6. It replaced the use of power triodes in public-address amplifiers almost overnight, so many applications were found for the 6L6 that a complete list would be impossible to assemble. MOV introduced their version, the KT66, a year later, rCAs first version was an early octal base tube. Like most with this base it had a metal, rather than glass, later versions, including the 6L6G, 6L6GA, 6L6GB,5881,5932,7027, and the final version 6L6GC had glass envelopes, which made radiation cooling of the anode easier. The original metal version was rated for 19 watts dissipation while the later 6L6GC is usually rated for 30 watts, a W in the descriptor, as in 6L6WGB, identifies the tube as designed for mechanically rugged environments, such as military or airborne use. One of the largest-volume post-WWII applications was in the design of television sweep power tubes, starting with the 6BG6G. TV designs rarely used transistors in place of sweep tubes—a challenging high-power, for this reason the speaker terminals of 6L6 tube amplifiers are sometimes short-circuited by a switching 6.3 mm jack when the speakers are disconnected. Further testimony for this success would be even simpler, as of 2012 the 6L6GC version was still being manufactured and used. Manufacture continued in Russia, China, and Slovakia, the 6L6 has had one of the longest active lifetimes of any electronic component, more than 70 years. 5881 6P3S 6P3S-E 7027a 6V6 KT66 KT886550 6CA7 EL34 List of vacuum tubes Stokes,70 years of radio tubes and valves. History of the British radio valve to 1940, TDSL Tube data Electron Tube Data sheets, Several 6L6 datasheets from various manufacturers Kurt Prange. 6L6GC Comparison of Current Made Tubes
38.
6V6
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The 6V6 is a beam-power tetrode vacuum tube. The first of this family of tubes to be introduced was the 6V6G by Ken-Rad Tube & Lamp Corporation in late 1936 and it is still in use in audio applications, especially electric guitar amplifiers. Following the introduction in July 1936 of the 6L6, the potential of the scaled down version that became the 6V6 was soon realized, the 6V6 required less heater power and produced less distortion than the 6F6, while yielding higher output in both single-ended and push-pull configurations. Additionally, the 6V6 had applications in portable battery-operated radios, the RMA Release #125 –03 Jan.1938, Sponsored by RCA. for the 6V6 tube has led to some confusion as to the origins of the 6V6. The 6V6G but not the 6V6 is in the RCA manual RC-13 from July 1937, the introduction of the 6V6GT, RMA Release #201 –10 July 1939, was sponsored by Hytron Corporation. By 1940, the 6V6G production was largely superseded by this smaller GT T-9 glass envelope, the 6V6GTA – RMA Release #1681 –2 July 1956, sponsored by Hygrade Sylvania Corporation, has a controlled warm-up period. The various different NOS tubes of the 6V6 family, depending on manufacturer, model, series, strength and condition, will vary enormously in scarcity and therefore usually in price. In the final years of U. S. production, several of the manufacturers switched to using the so-called coin based GT bulb. Although historically widely used in all manner of goods, many of which are still in service. Generally speaking, 6V6 tubes are sturdy and can be operated beyond their published specifications and this ongoing demand encourages Chinese, Slovakian and Russian tube factories not only to keep the 6V6 in production to this day, but to further develop the supply. 6V6G – Glass Shouldered Tube ST envelope, the metal envelope of 6V6 is connected to pin 1 of the base, and was normally used as a ground. Pin 1 of the members of the 6V6 family of tubes are usually not internally connected. 6V6GT – smaller Glass Tube T-9 envelope, 6V6GTA – with a controlled warm-up period. 6V6GTY – a GT with a low loss micanol brown base, 6V6GTX = HY6V6GTX – a GT Bantam selected for high gain, with a ceramic base, 15W plate dissipation rating, produced for a limited period around 1941 by Hytron. 5871 – Ruggedized 6V6GT for operation under severe vibrations found in aircraft, Radio Valve Co. of Canada Ltd. 5992 – Premium, ruggedized 6V6GT with heater current raised to 600mA,7408 – 6V6GT with additional zero-bias characteristics. 6V6S – A modern production, large plated tube, heater current 500mA, with a reputation of handling high voltage and current ratings, 6V6GT-STR – Modern production valve, STR signifying Special Tube Request Claiming to be heavy duty, suitable for high plate voltage. Military specification 6V6 tubes and their equivalents American military services contracted tubes from many sources through the U. S and they used a Joint Army-Navy Nomenclature System Most of these tubes bare the JAN marking as well as a VT number
