1.
Punched card
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A punched card or punch card is a piece of stiff paper that can be used to contain digital information represented by the presence or absence of holes in predefined positions. The information might be data for data processing applications or, in earlier examples, the terms IBM card, or Hollerith card specifically refer to punched cards used in semiautomatic data processing. Many early digital computers used punched cards, often prepared using keypunch machines, while punched cards are now obsolete as a recording medium, as of 2012, some voting machines still use punched cards to record votes. Basile Bouchon developed the control of a loom by punched holes in paper tape in 1725, in 1801 Joseph Marie Jacquard demonstrated a mechanism to automate loom operation. A number of punched cards were linked into a chain of any length, each card held the instructions for shedding and selecting the shuttle for a single pass. It is considered an important step in the history of computing hardware, semen Korsakov was reputedly the first to use the punched cards in informatics for information store and search. Korsakov announced his new method and machines in September 1832, rather than seeking patents, charles Babbage proposed the use of Number Cards, pierced with certain holes and stand opposite levers connected with a set of figure wheels. Advanced they push in those levers opposite to which there are no holes on the card, Herman Hollerith invented the recording of data on a medium that could then be read by a machine. Prior uses of machine readable media, such as those above, had been for control, after some initial trials with paper tape, he settled on punched cards. Developing punched card data processing technology for the 1890 US census, other companies entering the punched card business included the Powers Accounting Machine Company, Remington Rand, and Groupe Bull. Both IBM and Remington Rand tied punched card purchases to machine leases, in 1932, the US government took both to court on this issue. IBM viewed its business as providing a service and that the cards were part of the machine, IBM fought all the way to the Supreme Court and lost in 1936, the court ruling that IBM could only set card specifications. According to the IBM Archives, By 1937, IBM had 32 presses at work in Endicott, N. Y. printing, cutting and stacking five to 10 million punched cards every day. Punched cards were used as legal documents, such as U. S. Government checks. Punched card technology developed into a tool for business data-processing. By 1950 punched cards had become ubiquitous in industry and government, do not fold, spindle or mutilate, a generalized version of the warning that appeared on some punched cards, became a motto for the post-World War II era. In 1955 IBM signed a consent decree requiring, amongst other things, tom Watson Jr. s decision to sign this decree, where IBM saw the punched card provisions as the most significant point, completed the transfer of power to him from Thomas Watson, Sr. The UNITYPER introduced magnetic tape for data entry in the 1950s, during the 1960s, the punched card was gradually replaced as the primary means for data storage by magnetic tape, as better, more capable computers became available
2.
Herman Hollerith
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Herman Hollerith was an American inventor who developed an electromechanical punched card tabulator to assist in summarizing information and, later, accounting. He was the founder of the Tabulating Machine Company that was amalgamated in 1911 with three companies to form a fifth company, the Computing-Tabulating-Recording Company later renamed IBM. Hollerith is regarded as one of the figures in the development of data processing. His invention of the punched card tabulating machine marks the beginning of the era of data processing systems. Herman Hollerith was born the son of German immigrant Prof. Georg Hollerith from Großfischlingen in Buffalo, New York, in 1882 Hollerith joined the Massachusetts Institute of Technology where he taught mechanical engineering and conducted his first experiments with punched cards. He died in Washington D. C. of a heart attack, at the urging of John Shaw Billings, Hollerith developed a mechanism using electrical connections to increment a counter, recording information. A key idea was that a datum could be recorded by the presence or absence of a hole at a location on a card. For example, if a hole location indicates marital status. Hollerith determined that data in specified locations on a card, the rows and columns. A description of system, An Electric Tabulating System, was submitted by Hollerith to Columbia University as his doctoral thesis. On January 8,1889, Hollerith was issued U. S. Hollerith had left teaching, titled Art of Compiling Statistics, it was filed on September 23,1884, U. S. Patent 395,782 was granted on January 8,1889, Hollerith initially did business under his own name, as The Hollerith Electric Tabulating System, specializing in punched card data processing equipment. He built tabulators and other machines under contract for the Census Office, in 1896 Hollerith founded the Tabulating Machine Company. Many major census bureaus around the world leased his equipment and purchased his cards, as did major insurance companies. Holleriths machines were used for censuses in England, Italy, Germany, Russia, Austria, Canada, France, Norway, Puerto Rico, Cuba, and the Philippines and he invented the first automatic card-feed mechanism and the first keypunch. The 1890 Tabulator was hardwired to operate on 1890 Census cards, a control panel in his 1906 Type I Tabulator simplified rewiring for different jobs. The 1920s removable control panel supported prewiring and near instant job changing and these inventions were among the foundations of the data processing industry and Holleriths punched cards continued in use for almost a century. In 1911 four corporations, including Holleriths firm, were amalgamated to form a fifth company, under the presidency of Thomas J. Watson, CTR was renamed International Business Machines Corporation in 1924
3.
Supercomputer
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A supercomputer is a computer with a high level of computing performance compared to a general-purpose computer. Performance of a supercomputer is measured in floating-point operations per second instead of instructions per second. As of 2015, there are supercomputers which can perform up to quadrillions of FLOPS and it tops the rankings in the TOP500 supercomputer list. Sunway TaihuLights emergence is also notable for its use of indigenous chips, as of June 2016, China, for the first time, had more computers on the TOP500 list than the United States. However, U. S. built computers held ten of the top 20 positions, in November 2016 the U. S. has five of the top 10, throughout their history, they have been essential in the field of cryptanalysis. The use of multi-core processors combined with centralization is an emerging trend, the history of supercomputing goes back to the 1960s, with the Atlas at the University of Manchester and a series of computers at Control Data Corporation, designed by Seymour Cray. These used innovative designs and parallelism to achieve superior computational peak performance, Cray left CDC in 1972 to form his own company, Cray Research. Four years after leaving CDC, Cray delivered the 80 MHz Cray 1 in 1976, the Cray-2 released in 1985 was an 8 processor liquid cooled computer and Fluorinert was pumped through it as it operated. It performed at 1.9 gigaflops and was the second fastest after M-13 supercomputer in Moscow. Fujitsus Numerical Wind Tunnel supercomputer used 166 vector processors to gain the top spot in 1994 with a speed of 1.7 gigaFLOPS per processor. The Hitachi SR2201 obtained a performance of 600 GFLOPS in 1996 by using 2048 processors connected via a fast three-dimensional crossbar network. The Intel Paragon could have 1000 to 4000 Intel i860 processors in various configurations, the Paragon was a MIMD machine which connected processors via a high speed two dimensional mesh, allowing processes to execute on separate nodes, communicating via the Message Passing Interface. Approaches to supercomputer architecture have taken dramatic turns since the earliest systems were introduced in the 1960s, early supercomputer architectures pioneered by Seymour Cray relied on compact innovative designs and local parallelism to achieve superior computational peak performance. However, in time the demand for increased computational power ushered in the age of massively parallel systems, supercomputers of the 21st century can use over 100,000 processors connected by fast connections. The Connection Machine CM-5 supercomputer is a parallel processing computer capable of many billions of arithmetic operations per second. Throughout the decades, the management of heat density has remained a key issue for most centralized supercomputers, the large amount of heat generated by a system may also have other effects, e. g. reducing the lifetime of other system components. There have been diverse approaches to management, from pumping Fluorinert through the system. Systems with a number of processors generally take one of two paths
4.
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
5.
Columbia University
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Columbia University is a private Ivy League research university in Upper Manhattan, New York City. It was established in 1754 as Kings College by royal charter of George II of Great Britain, after the American Revolutionary War, Kings College briefly became a state entity, and was renamed Columbia College in 1784. Columbia is one of the fourteen founding members of the Association of American Universities and was the first school in the United States to grant the M. D. degree. The university also has global research outposts in Amman, Beijing, Istanbul, Paris, Mumbai, Rio de Janeiro, Santiago, Asunción, Columbia administers annually the Pulitzer Prize. Additionally,100 Nobel laureates have been affiliated with Columbia as students, researchers, faculty, Columbia is second only to Harvard University in the number of Nobel Prize-winning affiliates, with over 100 recipients of the award as of 2016. In 1746 an act was passed by the assembly of New York to raise funds for the foundation of a new college. Classes were initially held in July 1754 and were presided over by the colleges first president, Dr. Johnson was the only instructor of the colleges first class, which consisted of a mere eight students. Instruction was held in a new schoolhouse adjoining Trinity Church, located on what is now lower Broadway in Manhattan, in 1763, Dr. Johnson was succeeded in the presidency by Myles Cooper, a graduate of The Queens College, Oxford, and an ardent Tory. In the charged political climate of the American Revolution, his opponent in discussions at the college was an undergraduate of the class of 1777. The suspension continued through the occupation of New York City by British troops until their departure in 1783. The colleges library was looted and its sole building requisitioned for use as a hospital first by American. Loyalists were forced to abandon their Kings College in New York, the Loyalists, led by Bishop Charles Inglis fled to Windsor, Nova Scotia, where they founded Kings Collegiate School. After the Revolution, the college turned to the State of New York in order to restore its vitality, the Legislature agreed to assist the college, and on May 1,1784, it passed an Act for granting certain privileges to the College heretofore called Kings College. The Regents finally became aware of the colleges defective constitution in February 1787 and appointed a revision committee, in April of that same year, a new charter was adopted for the college, still in use today, granting power to a private board of 24 Trustees. On May 21,1787, William Samuel Johnson, the son of Dr. Samuel Johnson, was unanimously elected President of Columbia College, prior to serving at the university, Johnson had participated in the First Continental Congress and been chosen as a delegate to the Constitutional Convention. The colleges enrollment, structure, and academics stagnated for the majority of the 19th century, with many of the college presidents doing little to change the way that the college functioned. In 1857, the college moved from the Kings College campus at Park Place to a primarily Gothic Revival campus on 49th Street and Madison Avenue, during the last half of the 19th century, under the leadership of President F. A. P. Barnard, the institution assumed the shape of a modern university
6.
United States Constitution
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The United States Constitution is the supreme law of the United States of America. The Constitution, originally comprising seven articles, delineates the national frame of government, Articles Four, Five and Six entrench concepts of federalism, describing the rights and responsibilities of state governments and of the states in relationship to the federal government. Article Seven establishes the procedure used by the thirteen States to ratify it. In general, the first ten amendments, known collectively as the Bill of Rights, offer specific protections of individual liberty, the majority of the seventeen later amendments expand individual civil rights protections. Others address issues related to federal authority or modify government processes and procedures, Amendments to the United States Constitution, unlike ones made to many constitutions worldwide, are appended to the document. All four pages of the original U. S, according to the United States Senate, The Constitutions first three words—We the People—affirm that the government of the United States exists to serve its citizens. From September 5,1774 to March 1,1781, the Continental Congress functioned as the government of the United States. The process of selecting the delegates for the First and Second Continental Congresses underscores the revolutionary role of the people of the colonies in establishing a governing body. The Articles of Confederation and Perpetual Union was the first constitution of the United States and it was drafted by the Second Continental Congress from mid-1776 through late-1777, and ratification by all 13 states was completed by early 1781. Under the Articles of Confederation, the governments power was quite limited. The Confederation Congress could make decisions, but lacked enforcement powers, implementation of most decisions, including modifications to the Articles, required unanimous approval of all thirteen state legislatures. The Continental Congress could print money but the currency was worthless, Congress could borrow money, but couldnt pay it back. No state paid all their U. S. taxes, some paid nothing, some few paid an amount equal to interest on the national debt owed to their citizens, but no more. No interest was paid on debt owed foreign governments, by 1786, the United States would default on outstanding debts as their dates came due. Internationally, the Articles of Confederation did little to enhance the United States ability to defend its sovereignty, most of the troops in the 625-man United States Army were deployed facing – but not threatening – British forts on American soil. They had not been paid, some were deserting and others threatening mutiny, spain closed New Orleans to American commerce, U. S. officials protested, but to no effect. Barbary pirates began seizing American ships of commerce, the Treasury had no funds to pay their ransom, if any military crisis required action, the Congress had no credit or taxing power to finance a response. Domestically, the Articles of Confederation was failing to bring unity to the sentiments and interests of the various states
7.
Conductor (rail)
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A conductor or guard is a train crew member responsible for operational and safety duties that do not involve actual operation of the train. The conductor title is most common in North American railway operations, in Commonwealth English, a conductor is only responsible for selling tickets. The conductor often stays in the center of the train where they can best view the platform, Conductor is also a crew member in some bus, trolleybus or tram operations. All crew members work under the conductor, the conductor, engineer, and additional engine crew members share responsibility for safe and efficient train operation and adherence to railway rules and procedures. On some railroads, union contracts specify that conductors must progress to engineer, onboard service crew members on passenger trains normally remain on duty for the entire run, including assigned meal and sleep breaks. Since nearly the beginning of railroading in North America, the conductor on freight trains rode aboard a caboose, along with the flagman and the rear brakeman. Advances in technology and pressure to reduce operating costs made cabooses redundant and this relocated the conductor from the rear of the train to the locomotive at the head of the train. In most cases, these same conditions gradually eliminated members of the crew under the conductor—head and rear brakemen, flagmen. Most freight trains on most railroads today have a crew of two, one conductor and one engineer, railroad companies continue to press for reduced operating and labor costs and this threatens to eliminate conductors. Railroads rationalize that since the engineer is already qualified as a conductor, in fact, on most railroads, engineers begin as brakemen/assistant conductors, then become conductors, and finally engineers. Some railroads already implement such a strategy, notably the Montana Rail Link, and operate with an engineer, therefore, eliminating the conductor position would require that the railroads and unions negotiate a new agreement. If the railroads were successful, conductors already trained and certified as engineers would be able to work as engineers and those that have not yet progressed to engineer would have to be trained as engineers as positions became available. Others would have to accept other positions or possibly lose their jobs, the primary union for engineers, the Brotherhood of Locomotive Engineers does not support this movement, claiming that requiring its members to operate trains alone would be unsafe. The conductors union, the United Transportation Union, also opposes this initiative, by the late 1990s, remote control locomotives were increasingly popular on North American railroads for switching duties in rail yards. This system allows the conductor to control the locomotive via a wireless remote unit. Some Class I Rail Yards utilize RCO packs for their conductors, while others do not, depending on the size, Class I Railroads train conductors on the use of RCO packs with classroom and hands-on instruction, culminating with on-the-job training and certification as a RCO operator. Currently, Class I railroads such as Norfolk Southern require RCO qualified conductors to work from job boards that perform RCO operations exclusively and this ensures the extra training and pay these conductors receive will provide the company with maximum value for the investment. Before operation began, the FRA required FrontRunner to employ a second crewmember on each train to assist with evacuation, disabled access
8.
Ticket (admission)
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A ticket may be free, and serve simply as a proof of reservation. The first known tickets were used in the Greek period for events that took place in theatres. One can buy a ticket at a window or counter. The ticket check may also be there, or it may be separate, tickets are also available from resellers. Resellers typically are commercial enterprises that purchase tickets in bulk, and resell them to members of the public, consumers patronize resellers for reasons of convenience and availability. The convenience factor relates to being able to obtain tickets locally, the availability factor relates to the fact that all tickets may have been sold out at the box office, requiring the purchaser to either obtain tickets from the reseller, or not to see the show. A ticket may be valid for any seat or for a specific one, sometimes, ex, for some train journeys, both are available, with an increased charge for a reserved seat. Free seating in a means the risk that one has to stand, but in ex. Paper or card is used, although plastic may be used instead for durability. Some have a barcode or magnetic stripe for keeping simple data stored on them, higher end ones use chips to store more data and prevent counterfeiting. A paper ticket often is perforated so it can be separated into two parts, one to be kept by the customer, and one to be kept by the ticket controller, whether or not one can leave and reenter with the customer part only varies. Tickets may be printed in advance, or fully or partly printed when issued, counterfeit tickets are a problem at high-priced concerts and other events, so holograms are used on tickets for the Olympic Games, Super Bowl, FIFA World Cup and other high-profile events. The fraudulent practice of passing-back a ticket can be overcome by making the ticket in the form of a tamper-proof wristband, when paying online for admission one may get a code, or a ticket that can be printed out. At the premises, it is sure that the same right of admission is not used twice. Internet ticket fraud has become widespread, with authentic-looking but fake ticket websites taking customers money but not delivering the tickets, free tickets are applied in virtual queueing. In a place one has to wait ones turn, there may be the system that one takes a ticket with a number from a dispenser. This system is found in hospitals and surgeries, and at offices where many people visit, like town halls, social security offices, labor exchanges. Another form of virtual queuing is where the ticket carries a time-slot on it and this type of ticket would allow someone to do other things and then return for a roller-coaster ride, for example, without having to actually stand and wait in line
9.
Jacquard loom
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The Jacquard machine is a device fitted to a power loom that simplifies the process of manufacturing textiles with such complex patterns as brocade, damask and matelassé. It was invented by Joseph Marie Jacquard in 1804, the loom was controlled by a chain of cards, a number of punched cards, laced together into a continuous sequence. Multiple rows of holes were punched on each card, with one complete card corresponding to one row of the design, several such paper cards, generally white in color, can be seen in the images below. Chains, like Bouchons earlier use of tape, allowed sequences of any length to be constructed. It is based on earlier inventions by the Frenchmen Basile Bouchon, Jean Baptiste Falcon, a static display of a Jacquard loom is the centrepiece of the Musée des Tissus et des Arts décoratifs in Lyon. Live displays of a Jacquard loom are available at a few museums around Lyon and also twice a day at La Maison des Canuts. Both the Jacquard process and the necessary loom attachment are named after their inventor and this mechanism is probably one of the most important weaving inventions as Jacquard shedding made possible the automatic production of unlimited varieties of pattern weaving. The term Jacquard is not specific or limited to any particular loom, the process can also be used for patterned knitwear and machine-knitted textiles, such as jerseys. This use of punched cards to control a sequence of operations is considered an important step in the history of computing hardware. In former times, if figured designs were required, this was done on a drawloom, the heddles with warp ends to be pulled up were manually selected by a second operator, apart from the weaver. It was slow and labour-intensive, with limitations on the complexity of the pattern. The first important improvement of the draw took place in 1725. A continuous roll of paper was punched by hand, in sections, each of which represented one lash or tread, the Jacquard machine subsequently evolved from this. It is difficult to determine part of the Jacquard machine was designed by Jacquard himself. He may have combined the best mechanical elements of other inventors, Jacquards machine also contained eight rows of needles and uprights as compared with Vaucansons double row, of which modifications enabled him to increase the figuring capacity of the machine. In his first machine, he supported the harness by knotted cords, Jacquards invention had a deep influence on Charles Babbage. In that respect, he is viewed by some authors as a precursor of modern computing science. Each position in the card corresponds to a Bolus hook, which can either be raised or stopped dependent on whether the hole is punched out of the card or the card is solid
10.
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
11.
Mercury (element)
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Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum, Mercury occurs in deposits throughout the world mostly as cinnabar. The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide, likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in research applications and in amalgam for dental restoration in some locales. It is used in fluorescent lighting, electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce, making visible light. Mercury poisoning can result from exposure to water-soluble forms of mercury, Mercury is a heavy, silvery-white liquid metal. Compared to other metals, it is a conductor of heat. It has a point of −38.83 °C and a boiling point of 356.73 °C. Upon freezing, the volume of mercury decreases by 3. 59%, the coefficient of volume expansion is 181.59 × 10−6 at 0 °C,181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C. Solid mercury is malleable and ductile and can be cut with a knife, because this configuration strongly resists removal of an electron, mercury behaves similarly to noble gases, which form weak bonds and hence melt at low temperatures. The stability of the 6s shell is due to the presence of a filled 4f shell, an f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus. Like silver, mercury reacts with hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury, Mercury dissolves many other metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally used to trade mercury. Several other first row transition metals with the exception of manganese, copper, other elements that do not readily form amalgams with mercury include platinum. Sodium amalgam is a reducing agent in organic synthesis, and is also used in high-pressure sodium lamps. Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact, since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth, even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft, Mercury embrittlement is the most common type of liquid metal embrittlement
12.
Plugboard
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A plugboard, or control panel, is an array of jacks, or sockets, into which patch cords can be inserted to complete an electrical circuit. Control panels were used to direct the operation of unit record equipment. Plugboards were used on some machines, and some early computers. The earliest machines were hard wired for specific applications, Control panels were introduced in 1906 for the Hollerith Type 1 Tabulator. Removable control panels were introduced with the Hollerith type 3-S tabulator in the 1920s, applications then could be wired on separate control panels, and inserted into tabulators as needed. Removable control panels came to be used in all unit record machines where the use for different applications required rewiring. IBM removable control panels ranged in size from 6 1/4 by 10 3/4 to roughly one to two feet on a side and had an array of hubs. For example, in a card duplicator application a card column reading hub might be connected to a punch magnet entry hub and it was a relatively simple matter to copy some fields, perhaps to different columns, and ignore other columns by suitable wiring. Tabulator control panels could require dozens of patch cords for some applications, Tabulator functions were implemented with both mechanical and electrical components. Control panels simplified the changing of electrical connections for different applications, for most machines with control panels, from collators, interpreters, to the IBM407, IBM manuals describe the control panel as directing or automatic operation was obtained by. The control panels of calculators, such as the IBM602 and IBM604, unit record equipment was typically configured for a specific task using a removable control panel. Perhaps the closest modern analog is the gate array, where a fixed number of logic components are made available. Wiring a unit record control panel required knowledge of the machines components, the components of most unit record machines were synchronized to a rotating shaft. One rotation represented a single cycle, during which punched cards would advance from one station to the next, a line might be printed. The cycles were divided into points according to when the rows on a card would appear under a read or punch station. On most machines, cards were fed face down, 9-edge first, thus the first point in a card cycle would 9-time, the second 8 time and so on to 0-time. The times from 9 to 0 were known as digits and these would be followed by 11 time and 12 time, also known as zones. In a read station, a set of 80 spring wire brushes pressed against the card, each brush was connected to an individual hub on the control panel, from which it could be wired to another hub, as needed
