1.
Cadillac
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Cadillac /ˈkædᵻlæk/, formally the Cadillac Motor Car Division, is a division of the U. S. -based General Motors that markets luxury vehicles worldwide. Its primary markets are the United States, Canada, and China, historically, Cadillac automobiles have always held a place at the top of the luxury field within the United States. In 2016, Cadillacs U. S. sales were 170,006 vehicles, Cadillac is among the oldest automobile brands in the world, second in America only to fellow GM marque Buick. The firm was founded from the remnants of the Henry Ford Company in 1902 and it was named after Antoine de la Mothe Cadillac, who founded Detroit, Michigan. The Cadillac crest is based on his coat of arms, by the time General Motors purchased the company in 1909, Cadillac had already established itself as one of Americas premier luxury carmakers. The complete interchangeability of its parts had allowed it to lay the foundation for the modern mass production of automobiles. It was at the forefront of advances, introducing full electrical systems, the clashless manual transmission. The brand developed three engines, with its V8 setting the standard for the American automotive industry and it won the trophy again in 1912 for incorporating electric starting and lighting in a production automobile. Cadillac was formed from the remnants of the Henry Ford Company, after a dispute between Henry Ford and his investors, Ford left the company along with several of his key partners in March 1902. Instead, Leland persuaded the pair to continue manufacturing automobiles using Lelands proven single-cylinder engine, a new company called the Cadillac Automobile Company was established on 22 August 1902, re-purposing the Henry Ford Company factory at Cass Street and Amsterdam Avenue. It was named after French explorer Antoine Laumet de La Mothe, sieur de Cadillac, Cadillacs first automobiles, the Runabout and Tonneau, were completed in October 1902. They were two-seat horseless carriages powered by a 10 hp single-cylinder engine and they were practically identical to the 1903 Ford Model A. Cadillac displayed the new vehicles at the New York Auto Show in January 1903, Cadillacs biggest selling point was precision manufacturing, and therefore, reliability, a Cadillac was simply a better-made vehicle than its competitors. Runabout Rear-entrance tonneau Special bodies The Cadillac Automobile Company merged with Leland & Faulconer Manufacturing, forming The Cadillac Motor Company in 1905. From its earliest years, Cadillac aimed for precision engineering and stylish luxury finishes, Cadillac was the first volume manufacturer of a fully enclosed car in 1906. Cadillac participated in the 1908 interchangeability test in the United Kingdom, in 1912, Cadillac was the first automobile manufacturer to incorporate an electrical system enabling starting, ignition, and lighting. Cadillac was purchased by the General Motors conglomerate in 1909, Cadillac became General Motors prestige division, devoted to the production of large luxury vehicles. It was positioned at the top of GMs vehicle hierarchy, above Buick, Oldsmobile, Oakland, in 1915, Cadillac introduced a 90-degree flathead V8 engine with 70 horsepower at 2400 rpm and 180 pound force-feet of torque, allowing its cars to attain 65 miles per hour
2.
V8 engine
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A V8 engine is an eight-cylinder V configuration engine with the cylinders mounted on the crankcase in two sets of four, with all eight pistons driving a common crankshaft. Most banks are set at an angle to each other, some at a narrower angle, with 45°, 60°. In its simplest form, the V8 is basically two parallel inline-four engines sharing a common crankshaft, since the 1920s, most V8s have used the somewhat more complex crossplane crankshaft with heavy counterweights to eliminate the vibrations. This results in an engine that is smoother than a V6, most racing V8s continue to use the single plane crankshaft because it allows faster acceleration and more efficient exhaust system designs. In 1902, Léon Levavasseur took out a patent on a light and he called it the Antoinette after the young daughter of his financial backer. From 1904 he installed this engine in a number of competition speedboats, the aviation pioneer Alberto Santos-Dumont saw one of these boats in Côte dAzur and decided to try it on his 14-bis aircraft. Its early 24 hp at 1400 rpm version with only 55 kg of weight was interesting, Santos-Dumont ordered a larger and more powerful version from Levavasseur. He changed its dimensions from the original 80 mm stroke and 80 mm bore to 105 mm stroke and 110 mm bore, obtaining 50 hp with 86 kg of weight and its power-to-weight ratio was not surpassed for 25 years. Levavasseur eventually produced its own line of V8 equipped aircraft, named Antoinette I to VIII, hubert Latham piloted the V8 powered Antoinette IV and Antoinette VII in July 1909 on two failed attempts to cross the English Channel. However, in 1910, Latham used the VII with the engine to become the first in the world to reach an altitude of 3600 feet. Voisin constructed pusher biplanes with Antoinette engines, also, notably the one first flown successfully by Henry Farman in 1908, the V8 engine configuration became popular in France from 1904 onward, and was used in a number of aircraft engines introduced by Renault, and Buchet among others. Some of these found their way into automobiles in small quantities. In 1905, Darracq built a car to beat the world speed record. They came up with two racing car built on a common crankcase and camshaft. The result was monstrous engine with a displacement of 1,551 cu in, victor Hemery fixed that record on 30 December 1905 with a speed of 109.65 mph. Rolls-Royce built a 3,535 cc V8 car from 1905 to 1906, in 1907 The Hewitt Motor Company built a large 5 passenger Touring Car. It was equipped with a hefty V8 engine that developed 50/60 horsepower and had a bore of 4 inches, the Hewitt was the first American Automobile to be equipped with a V8 engine. De Dion-Bouton introduced a 7,773 cc automobile V8 in 1910 and it was produced only in small quantities, but inspired a number of manufacturers to follow suit
3.
Cylinder block
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A cylinder block is an integrated structure comprising the cylinder of a reciprocating engine and often some or all of their associated surrounding structures. The term engine block is used synonymously with cylinder block. In the basic terms of elements, the various main parts of an engine are conceptually distinct. However, it is no longer the way of building most petrol engines and diesel engines, because for any given engine configuration. These generally involve integrating multiple machine elements into one discrete part and this yields lower unit cost of production. Thus engine block, cylinder block, or simply block are the likely to be heard in the garage or on the street. This evolution has occurred throughout the history of reciprocating engines, with instances of every conceptual variation coexisting here and there. The increase in prevalence of ever-more-integrated designs relied on the development of foundry. For example, a practical low-cost V8 engine was not feasible until Ford developed the techniques used to build the Ford flathead V8 engine, which soon also disseminated to the larger society. Today the foundry and machining processes for manufacturing engines are highly automated. A cylinder block is a unit comprising several cylinders, in the earliest decades of internal combustion engine development, monobloc cylinder construction was rare, cylinders were usually cast individually. Combining their castings into pairs or triples was a win of monobloc design. A wet liner cylinder block features cylinder walls that are entirely removable and they are referred to as wet liners because their outer sides come in direct contact with the engines coolant. In other words, the liner is the wall, rather than being merely a sleeve. Wet liner designs are popular with European manufacturers, most notably Renault and Peugeot, dry liner designs use either the blocks material or a discrete liner inserted into the block to form the backbone of the cylinder wall. Additional sleeves are inserted within, which dry on their outside. It is likelier to be scrapped, with new equipment—engine or entire vehicle—replacing it, most early engines, particularly those with more than four cylinders, had their cylinders cast as pairs or triplets of cylinders, then bolted to a single crankcase. As casting techniques improved, a cylinder block of 4,6
4.
Aluminium
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Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
5.
Cylinder head
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In an internal combustion engine, the cylinder head sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber and this joint is sealed by a head gasket. In most engines, the head also provides space for the passages that feed air and fuel to the cylinder, the head can also be a place to mount the valves, spark plugs, and fuel injectors. With a chain drive to a camshaft, the extra length of chain needed for an overhead cam design could give trouble from wear. Early sidevalve engines were in use at a time of simple fuel chemistry, low octane ratings and this made their combustion chamber design less critical and there was less need to design their ports and airflow carefully. One difficulty experienced at this time was that the low compression ratio also implied a low expansion ratio during the power stroke, exhaust gases were thus still hot, hotter than a contemporary engine, and this led to frequent trouble with burnt exhaust valves. A major improvement to the engine was the advent of Ricardos turbulent head design. This reduced the space within the chamber and the ports. Most importantly, it used turbulence within the chamber to thoroughly mix the fuel and this, of itself, allowed the use of higher compression ratios and more efficient engine operation. Despite common knowledge, the limit on performance is not the gas flow through the valves. With high speed engines and high compression, the limiting difficulty becomes that of achieving complete and efficient combustion, modern, efficient engines thus tend towards the pent roof or hemi designs, where the valves are brought close in to the centre of the space. Where fuel quality is low and octane rating is poor, compression ratios will be restricted, in these cases, the sidevalve engine still has much to offer. Such engines remained in production into the 1990s, only being replaced when the fuels available in the field became more likely to be diesel than petrol. In the overhead valve design, the head contains the poppet valves. In the overhead camshaft design, the head contains the valves, spark plugs and inlet/exhaust tracts just like the OHV engine. The number of heads in an engine is a function of the engine configuration. Almost all inline engines today use a cylinder head that serves all the cylinders. A V engine has two heads, one for each cylinder bank of the V
6.
Cast iron
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Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its low melting temperature. Carbon ranging from 1. 8–4 wt%, and silicon 1–3 wt% are the main alloying elements of cast iron, Iron alloys with less carbon content are known as steel. While this technically makes the Fe–C–Si system ternary, the principle of cast iron solidification can be understood from the simpler binary iron–carbon phase diagram, cast iron tends to be brittle, except for malleable cast irons. It is resistant to destruction and weakening by oxidation, the earliest cast iron artefacts date to the 5th century BC, and were discovered by archaeologists in what is now Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture, during the 15th century, cast iron became utilized for artillery in Burgundy, France, and in England during the Reformation. The first cast iron bridge was built during the 1770s by Abraham Darby III, cast iron is also used in the construction of buildings. Cast iron is made by re-melting pig iron, often along with quantities of iron, steel, limestone, carbon. Phosphorus and sulfur may be burnt out of the iron, but this also burns out the carbon. Depending on the application, carbon and silicon content are adjusted to the desired levels, other elements are then added to the melt before the final form is produced by casting. Cast iron is melted in a special type of blast furnace known as a cupola. After melting is complete, the molten cast iron is poured into a furnace or ladle. Cast irons properties are changed by adding various alloying elements, or alloyants, next to carbon, silicon is the most important alloyant because it forces carbon out of solution. A low percentage of silicon allows carbon to remain in solution forming iron carbide, a high percentage of silicon forces carbon out of solution forming graphite and the production of grey cast iron. Other alloying agents, manganese, chromium, molybdenum, titanium and vanadium counteracts silicon, promotes the retention of carbon, nickel and copper increase strength, and machinability, but do not change the amount of graphite formed. The carbon in the form of graphite results in an iron, reduces shrinkage, lowers strength. Sulfur, largely a contaminant when present, forms iron sulfide, the problem with sulfur is that it makes molten cast iron viscous, which causes defects. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide, the manganese sulfide is lighter than the melt so it tends to float out of the melt and into the slag
7.
Fuel
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A fuel is any material that can be made to react with other substances so that it releases chemical or nuclear energy as heat or to be used for work. The concept was applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy such as nuclear energy. The heat energy released by reactions of fuels is converted into mechanical energy via a heat engine, other times the heat itself is valued for warmth, cooking, or industrial processes, as well as the illumination that comes with combustion. Fuels are also used in the cells of organisms in a known as cellular respiration. Hydrocarbons and related oxygen-containing molecules are by far the most common source of fuel used by humans, fuels are contrasted with other substances or devices storing potential energy, such as those that directly release electrical energy or mechanical energy. The first known use of fuel was the combustion of wood or sticks by Homo erectus near 2,000,000 years ago, throughout most of human history fuels derived from plants or animal fat were only used by humans. Charcoal, a derivative, has been used since at least 6,000 BCE for melting metals. It was only supplanted by coke, derived from coal, as European forests started to become depleted around the 18th century, charcoal briquettes are now commonly used as a fuel for barbecue cooking. Coal was first used as a fuel around 1000 BCE in China, coal was later used to drive ships and locomotives. By the 19th century, gas extracted from coal was being used for lighting in London. In the 20th and 21st centuries, the use of coal is to generate electricity. Fossil fuels were rapidly adopted during the revolution, because they were more concentrated and flexible than traditional energy sources. They have become a part of our contemporary society, with most countries in the world burning fossil fuels in order to produce power. Currently the trend has been towards renewable fuels, such as biofuels like alcohols, chemical fuels are substances that release energy by reacting with substances around them, most notably by the process of combustion. Most of the energy released in combustion was not stored in the chemical bonds of the fuel. Chemical fuels are divided in two ways, first, by their physical properties, as a solid, liquid or gas. Secondly, on the basis of their occurrence, primary and secondary, solid fuels include wood, charcoal, peat, coal, Hexamine fuel tablets, and pellets made from wood, corn, wheat, rye and other grains. Solid-fuel rocket technology also uses solid fuel, solid fuels have been used by humanity for many years to create fire
8.
Gasoline
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Gasoline /ˈɡæsəliːn/, known as petrol /ˈpɛtrəl/ outside North America, is a transparent, petroleum-derived liquid that is used primarily as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the distillation of petroleum. On average, a 42-gallon barrel of oil yields about 19 US gallons of gasoline when processed in an oil refinery. The characteristic of a gasoline blend to resist igniting too early is measured by its octane rating. Gasoline is produced in several grades of octane rating, sometimes, gasoline also contains ethanol as an alternative fuel, for economic or environmental reasons. Gasoline, as used worldwide in the vast number of combustion engines used in transport and industry, has a significant impact on the environment. Gasoline may also enter the environment uncombusted, as liquid and as vapors, from leakage and handling during production, transport and delivery, from tanks, from spills. As an example of efforts to control leakage, many storage tanks are required to have extensive measures in place to detect. Gasoline contains benzene and other known carcinogens, Gasoline inhalation can produce an intense high, however the practice is thought to cause severe organ damage, including mental retardation. The first automotive combustion engines, so-called Otto engines, were developed in the last quarter of the 19th century in Germany, the fuel was a relatively volatile hydrocarbon obtained from coal gas. With a boiling point near 85 °C, it was suited for early carburetors. The development of a spray nozzle carburetor enabled the use of less volatile fuels, further improvements in engine efficiency were attempted at higher compression ratios, but early attempts were blocked by knocking. In the 1920s, antiknock compounds were introduced by Thomas Midgley Jr. and Boyd and this innovation started a cycle of improvements in fuel efficiency that coincided with the large-scale development of oil refining to provide more products in the boiling range of gasoline. In the 1950s oil refineries started to focus on high octane fuels, the 1970s witnessed greater attention to the environmental consequences of burning gasoline. These considerations led to the out of TEL and its replacement by other antiknock compounds. Subsequently, low-sulfur gasoline was introduced, in part to preserve the catalysts in modern exhaust systems, Gasoline is the term that is used in North America to refer to the most popular automobile fuel. The Oxford English Dictionary dates the first use to 1863, when it was spelled gasolene and it was never a trademark, although it may have been derived from older trademarks such as Cazeline and Gazeline. Variant spellings of gasoline had been used to refer to raw petroleum since the 16th century, Petrol is the preferred term in most Commonwealth countries
9.
Motor oil
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Motor oil, engine oil, or engine lubricant is any of various substances are often used for lubrication of internal combustion engines. Motor oils are derived from petroleum-based and non-petroleum-synthesized chemical compounds, motor oils today are mainly blended by using base oils composed of hydrocarbons, polyalphaolefins, and polyinternal olefins, organic compounds consisting entirely of carbon and hydrogen. The base oils of some high-performance motor oils contain up to 20% by weight of esters, on September 6,1866 American John Ellis founded the Continuous Oil Refining Company. While studying the healing powers of crude oil, Dr. Ellis was disappointed to find no real medicinal value. He made his breakthrough when he developed an oil that worked effectively in high temperatures and this meant no more gummed valves, corroded cylinders or leaking seals. In 1873 Ellis officially renamed the company to Valvoline after the engine valves the product lubricated. Motor oil is a lubricant used in combustion engines, which power cars, motorcycles, lawnmowers, engine-generators. In engines, there are parts which move against each other, and it also wears away those parts, which could lead to lower efficiency and degradation of the engine. This increases fuel consumption, decreases power output, and can lead to engine failure, in petrol engines, the top piston ring can expose the motor oil to temperatures of 160 °C. In diesel engines the top ring can expose the oil to temperatures over 315 °C, motor oils with higher viscosity indices thin less at these higher temperatures. Coating metal parts with oil also keeps them from being exposed to oxygen, corrosion inhibitors may also be added to the motor oil. Many motor oils also have detergents and dispersants added to keep the engine clean. The oil is able to trap soot from combustion in itself and it is a combination of this, and some singeing that turns used oil black after some running. Rubbing of metal engine parts produces some microscopic metallic particles from the wearing of the surfaces. Such particles could circulate in the oil and grind against moving parts, because particles accumulate in the oil, it is typically circulated through an oil filter to remove harmful particles. An oil pump, a vane or gear pump powered by the engine, pumps the oil throughout the engine, Oil filters can be a full flow or bypass type. In the crankcase of an engine, motor oil lubricates rotating or sliding surfaces between the crankshaft journal bearings, and rods connecting the pistons to the crankshaft. The oil collects in an oil pan, or sump, at the bottom of the crankcase
10.
Water cooling
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Water cooling is a method of heat removal from components and industrial equipment. As opposed to air cooling, water is used as the heat conductor, the main mechanism for water cooling is convective heat transfer. Cooling water is the water removing heat from a machine or system, cooling water may be recycled through a recirculating system or used in a single pass once-through cooling system. Recirculating systems may be if they rely upon cooling towers or cooling ponds to remove heat or closed if heat removal is accomplished with negligible evaporative loss of cooling water. Environmental regulations emphasize the reduced concentrations of waste products in non-contact cooling water, the advantages of using water cooling over air cooling include waters higher specific heat capacity, density, and thermal conductivity. This allows water to heat over greater distances with much less volumetric flow. The water jacket around an engine is very effective at deadening mechanical noises. Water accelerates corrosion of parts and is a favorable medium for biological growth. Dissolved minerals in water supplies are concentrated by evaporation to leave deposits called scale. Cooling water often requires addition of chemicals to minimize corrosion and insulating deposits of scale, an open water cooling system makes use of evaporative cooling, lowering the temperature of the remaining water. This method was common in internal combustion engines, until scale buildup was observed from dissolved salts. Modern open cooling systems continuously waste a fraction of recirculating water as blowdown to remove dissolved solids at low enough to prevent scale formation. Some open systems use inexpensive tap water, but this requires higher rates than deionized or distilled water. Purified water systems still require blowdown to remove accumulation of byproducts of chemical treatment to prevent corrosion, modern automotive cooling systems are slightly pressurized, often to 15 psi. This raises the boiling-point of the coolant and reduces evaporation, the use of water cooling carries the risk of damage from freezing. Automotive and many other engine cooling applications require the use of a water, antifreeze also inhibits corrosion from dissimilar metals and can increase the boiling point, allowing a wider range of water cooling temperatures. Its distinctive odor also alerts operators to cooling system leaks and problems that would go unnoticed in a cooling system. The heated coolant mixture can also be used to warm the air conditioning system inside the car by means of the heater core, other less common chemical additives are products to reduce surface tension
11.
General Motors
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With global headquarters at the Renaissance Center in Detroit, Michigan, United States, GM manufactures cars and trucks in 35 countries. In 2008,8.35 million GM cars and trucks were sold globally under various brands, current auto brands are Buick, Cadillac, Chevrolet, GMC, Holden, and Wuling. Former GM automotive brands include McLaughlin, Oakland, Oldsmobile, Pontiac, Hummer, Saab, Saturn, Vauxhall, the company was founded by William C. Durant on September 16,1908 as a holding company. The company was the largest automobile manufacturer from 1931 through 2007, in addition to brands selling assembled vehicles, GM also has had various automotive-component and non-automotive brands, many of which it divested in the 1980s through 2000s. General Motors produces vehicles in 37 countries under twelve brands, Chevrolet, Buick, GMC, Cadillac, Holden, HSV, Opel, Vauxhall, Wuling, Baojun, Jie Fang, and Ravon. The current company, General Motors Company LLC, was formed in 2009 following the bankruptcy of General Motors Corporation, the new company purchased the majority of the assets of the old GM, including the brand General Motors. In addition to its twelve brands, General Motors also holds a 20% stake in IMM, General Motors employs 212,000 people and does business in more than 140 countries. General Motors is divided into five segments, GM North America, Opel Group, GM International Operations, GM South America. General Motors led global vehicle sales for 77 consecutive years from 1931 through 2007, longer any other automaker. General Motors acts in most countries outside the U. S. via wholly owned subsidiaries, GMs OnStar subsidiary provides vehicle safety, security and information services. In 2009, General Motors shed several brands, closing Saturn, Pontiac, and Hummer, in 2010, the reorganized GM made an initial public offering that was one of the worlds top five largest IPOs to date, and returned to profitability later that year. General Motors Corporation was formed on September 16,1908, in Flint, Michigan, GMs co-founder was Charles Stewart Mott, whose carriage company was merged into Buick prior to GMs creation. Over the years, Mott became the largest single stockholder in GM, and spent his life with his Mott Foundation, GM acquired Oldsmobile later that year. In 1909, Durant brought in Cadillac, Elmore, Oakland, also in 1909, GM acquired the Reliance Motor Truck Company of Owosso, Michigan, and the Rapid Motor Vehicle Company of Pontiac, Michigan, the predecessors of GMC Truck. Durant, along with R. S. McLaughlin, lost control of GM in 1910 to a bankers trust, because of the amount of debt taken on in its acquisitions. The next year, Durant started the Chevrolet Motor Car Company in the U. S. and in Canada in 1915, Durant took back control of the company after one of the most dramatic proxy wars in American business history. Durant then reorganized General Motors Company into General Motors Corporation in 1916, merging Chevrolet with GM, shortly thereafter, he again lost control, this time for good, after the new vehicle market collapsed. These facilities were added to the factories that were exclusive to Cadillac, Buick, Oldsmobile, Oakland
12.
EPROM
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An EPROM, or erasable programmable read-only memory, is a type of memory chip that retains its data when its power supply is switched off. Computer memory that can retrieve stored data after a power supply has been turned off and it is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages than those normally used in digital circuits. Once programmed, an EPROM can be erased by exposing it to ultraviolet light source. Development of the EPROM memory cell started with investigation of faulty integrated circuits where the connections of transistors had broken. Stored charge on these isolated gates changed their properties, the EPROM was invented by Dov Frohman of Intel in 1971, who was awarded US patent 3660819 in 1972. Each storage location of an EPROM consists of a single field-effect transistor, each field-effect transistor consists of a channel in the semiconductor body of the device. Source and drain contacts are made to regions at the end of the channel, an insulating layer of oxide is grown over the channel, then a conductive gate electrode is deposited, and a further thick layer of oxide is deposited over the gate electrode. The floating gate electrode has no connections to parts of the integrated circuit and is completely insulated by the surrounding layers of oxide. A control gate electrode is deposited and further oxide covers it, to retrieve data from the EPROM, the address represented by the values at the address pins of the EPROM is decoded and used to connect one word of storage to the output buffer amplifiers. Each bit of the word is a 1 or 0, depending on the transistor being switched on or off. The switching state of the transistor is controlled by the voltage on the control gate of the transistor. Presence of a voltage on this gate creates a channel in the transistor. In effect, the charge on the floating gate allows the threshold voltage of the transistor to be programmed. Storing data in the memory requires selecting a given address and applying a voltage to the transistors. This creates an avalanche discharge of electrons, which have enough energy to pass through the oxide layer. When the high voltage is removed, the electrons are trapped on the electrode, because of the high insulation value of the silicon oxide surrounding the gate, the stored charge cannot readily leak away and the data can be retained for decades. The programming process is not electrically reversible, to erase the data stored in the array of transistors, ultraviolet light is directed onto the die. Photons of the UV light cause ionization within the silicon oxide, since the whole memory array is exposed, all the memory is erased at the same time
