1.
Plastic film
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Plastic film is a thin continuous polymeric material. Thicker plastic material is called a “sheet”. These thin plastic membranes are used to separate areas or volumes, to items, to act as barriers. Plastic films are used in a variety of applications. These include, packaging, plastic bags, labels, building construction, landscaping, electrical fabrication, photographic film, film stock for movies, video tape, almost all plastics can be formed into a thin film. Polypropylene – Polypropylene can be made a cast film, biaxially oriented film, polyester – BoPET is a biaxially oriented polyester film Nylon Polyvinyl chloride – film can be with or without a Plasticizer A variety of bioplastics and biodegradable plastics are available. Cast – Plastics extrusion can cast film which is cooled or quenched then wound up on a roll, extruded film can be stretched, thinned, or oriented in one or two directions. Blown or tubular process forces air into a ring to expand the film. Flat tenter lines stretch the extruded film before annealing, calender rolls can be used to form film from hot polymers Solution deposition is another film forming process. Often additional coating or printing operations are also used, Films can be modified by physical vapor deposition to make metallised films. Films can be subjected to treatment or Plasma processing, films can have release agents applied as needed. Plastic Films, Technology and Packaging Applications, CRC Press 1992 Yam, K. L. Encyclopedia of Packaging Technology, John Wiley & Sons,2009, ISBN 978-0-470-08704-6
2.
Wire recording
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Wire recording or magnetic wire recording was the first early magnetic recording technology, an analog type of audio storage in which a magnetic recording is made on thin steel wire. The first crude magnetic recorder was invented in 1898 by Valdemar Poulsen, the principles and electronics involved are nearly identical. The first wire recorder was invented in 1898 by Danish-American engineer Valdemar Poulsen, Wire recorders for dictation and telephone recording were made almost continuously by various companies through the 1920s and 1930s, but use of this new technology was extremely limited. Dictaphone and Ediphone recorders, which still employed wax cylinders as the medium, were the devices normally used for these applications during this period. The brief heyday of wire recording lasted from approximately 1946 to 1954, the two organizations licensed dozens of manufacturers in the U. S. Japan, and Europe. Examples are Wilcox-Gay, Pierce, Webcor, and Air King, the popularity even encouraged Sears to provide a model, and some authors to prepare specialized manuals. The earliest magnetic tape recorders, not commercially available in the U. S. until 1948, were too expensive, complicated, for any given level of audio quality, the nearly hair-thin wire had the advantage that it was a much more compact storage medium than tape. The Minifon wire recorder was designed for use and its accessories included a microphone disguised as a wristwatch. There were also wire recorders made to data in satellites. Poulsens original telegraphone and other very early recorders placed the two poles of the head on opposite sides of the wire. The wire is thus magnetised transversely to the direction of travel, the development was to place the two poles on the same side of the wire so that the wire was magnetised along its length or longitudinally. Additionally, the poles were shaped into a V so that the head wrapped around the wire to some extent and this increased the magnetising effect and also increased the sensitivity of the head on replay because it collected more of the magnetic flux from the wire. This system was not entirely immune to twisting but the effects were far less marked, the longitudinal method survives into magnetic tape recording to this day. Compared to tape recorders, wire recording devices have a high media speed, standard postwar wire recorders use a nominal speed of 24 inches per second, making a typical one-hour spool of wire 7,200 feet long. Smaller 30- and 15-minute lengths of wire were employed by the majority of recorders made after 1945, some heavy-duty recorders use the larger Armour spools, which can contain enough wire to record continuously for several hours. Because the wire is pulled past the head by the take-up spool, to facilitate handling as the user threaded the wire across the recording head and affixed it to the take-up spool, some manufacturers attached a strip of plastic to each end of the wire. This was designed to press-fit snugly into either spool, on some machines, moving wire guides perform this function, like the mechanism that distributes line across a fishing reel. After recording or playback, the wire has to be rewound before any further use can be made of the machine, unlike with reel-to-reel tape recorders, the take-up reel on most wire recorders is not removable
3.
Tape recorder
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In its present-day form, it records a fluctuating signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal. Tape-recording devices include reel-to-reel tape deck and the cassette deck, the use of magnetic tape for sound recording originated around 1930. Magnetizable tape revolutionized both the radio broadcast and music recording industries and it gave artists and producers the power to record and re-record audio with minimal loss in quality as well as edit and rearrange recordings with ease. The alternative recording technologies of the era, transcription discs and wire recorders, since some early refinements improved the fidelity of the reproduced sound, magnetic tape has been the highest quality analog sound recording medium available. As of the first decade of the 21st century, analog magnetic tape has been replaced by digital recording technologies for consumer purposes. Some individuals and organizations developed innovative uses for magnetic wire recorders while others investigated variations of the technology, one particularly important variation was the application of an oxide powder to a long strip of paper. This German invention was the start of a string of innovations that have led to present day magnetic tape recordings. The earliest known audio tape recorder was a non-magnetic, non-electric version invented by Alexander Graham Bells Volta Laboratory and patented in 1886. It employed a 3⁄16-inch-wide strip of wax-covered paper that was coated by dipping it in a solution of beeswax and paraffin and then had one side scraped clean, the machine was of sturdy wood and metal construction, and hand-powered by means of a knob fastened to the flywheel. The tape was taken up on the other reel. The sharp recording stylus, actuated by a vibrating mica diaphragm, in playback mode, a dull, loosely mounted stylus, attached to a rubber diaphragm, carried the reproduced sounds through an ear tube to its listener. Both recording and playback heads, mounted alternately on the two posts, could be adjusted vertically so that several recordings could be cut on the same 3⁄16-inch-wide strip. While the machine was never developed commercially, it was an ancestor to the modern magnetic tape recorder which it resembled somewhat in design. The tapes and machine created by Bells associates, examined at one of the Smithsonian Institutions museums, became brittle, the machines playback head was also missing. Otherwise, with some reconditioning, they could be placed into working condition, during the recording process, the tape moved through a pair of electrodes which immediately imprinted the modulated sound signals as visible black stripes into the paper tapes surface. On 13 August 1931, Duston filed USPTO Patent Application #556,743 for Method Of And Apparatus For Electrically Recording And Reproducing Sound And Other Vibrations, and which was renewed in 1934. Magnetic recording was conceived as early as 1877 by the American engineer Oberlin Smith, Analog magnetic wire recording, and its successor, magnetic tape recording, involve the use of a magnetizable medium which moves with a constant speed past a recording head. An electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal
4.
Video tape recorder
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A video tape recorder is a tape recorder designed to record video material on magnetic tape. The first practical tape recorder, using transverse tape head scanning, was developed by Ampex Corporation in 1956. The early VTRs were reel to reel devices which recorded on reels of 2 inch wide magnetic tape. They were used in studios, serving as a replacement for motion picture film stock. Beginning in 1963, videotape machines made instant replay during televised sporting events possible, improved formats, in which the tape was contained inside a videocassette, were introduced around 1969, the machines which play them are called videocassette recorders. The first efforts at recording, using recorders similar to audio recorders with fixed heads, were unsuccessful. The problem was that a signal has a much wider bandwidth than an audio signal. One of the first efforts was the Vision Electronic Recording Apparatus and this machine used a thin steel tape on a 21-inch reel traveling at over 200 inches per second. Despite 10 years of research and improvements, it was never used due to the immense length of tape required for each minute of recorded video. Many other fixed-head recording systems were tried but all required impractically high tape speed and it became clear that practical video recording technology depended on finding some way of recording the wide-bandwidth video signal without the high tape speed required by linear-scan machines. The Ampex VRX-1000 became the worlds first commercially successful videotape recorder in 1956 and it used the 2 Quadruplex format, using two-inch tape. Because of its US$50,000 price, the Ampex VRX-1000 could be afforded only by the television networks and the largest individual stations. In 1963, Philips introduced its EL34001 helical scan recorder and Sony marketed the 2 PV-100, its first reel-to-reel VTR intended for business, medical, airline and educational use. The Telcan, produced by the Nottingham Electronic Valve Company and demonstrated on June 24,1963, was the first home video recorder and it could be bought as a unit or in kit form for £60. However, there were drawbacks, it was expensive, not easy to put together. The Sony model CV-2000, first marketed in 1965, was its first VTR intended for use and was based on half-inch tape. Ampex and RCA followed in 1965 with its own reel-to-reel monochrome VTRs priced under US $1,000 for the consumer market. Prerecorded movies for home replay became available in 1967, the EIAJ format was a standard half-inch format used by various manufacturers
5.
Tape drive
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A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is used for offline, archival data storage. Tape media generally has a unit cost and a long archival stability. A tape drive provides sequential access storage, unlike a hard disk drive, a disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As a result, tape drives have very slow average seek times to data, however, tape drives can stream data very quickly off a tape when the required position has been reached. For example, as of 2010 Linear Tape-Open supported continuous data transfer rates of up to 140 MB/s, magnetic tape drives were first used for data storage on mainframe computers in the 1950s, with capacities less than one megabyte. As technology advanced, capacities increased to 10 terabytes or higher of uncompressed data per cartridge as of 2014, in early computer systems, magnetic tape might be the main storage medium, although the drives were expensive, the tapes were inexpensive. The true storage capacity is known as the native capacity or the raw capacity. IBM and Sony have also used higher compression ratios in their marketing materials, the compression ratio actually achievable depends on the data being compressed. Some data has little redundancy, large files, for example, already use compression technology. A sparse database, on the hand, may allow compression ratios better than 10,1. Tape drives can be connected to a computer with SCSI, Fibre Channel, SATA, USB, FireWire, FICON, or other interfaces. Tape drives are used with autoloaders and tape libraries which automatically load, unload, in the early days of home computing, floppy and hard disk drives were very expensive. Many computers had an interface to store data via a tape recorder. Simple dedicated tape drives, such as the professional DECtape and the home ZX Microdrive, however, the drop in disk drive prices made such alternatives obsolete. In this situation, the modern fast-running tape drive is unable to stop the tape instantly, instead, the drive must decelerate and stop the tape, rewind it a short distance, restart it, position back to the point at which streaming stopped and then resume the operation. If the condition repeats, the resulting back-and-forth tape motion resembles that of shining shoes with a cloth, shoe-shining decreases the attainable data transfer rate, drive and tape life, and tape capacity. In early tape drives, non-continuous data transfer was normal and unavoidable, computer processing power and amounts of available memory were usually insufficient to provide a constant stream, so tape drives were typically designed for so called start-stop operation
6.
Sound recording and reproduction
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Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording, prior to the development of analog recording, there were mechanical systems for reproducing instrumental music, such as wind-up music boxes and later, in the late 19th century, player pianos. Analog sound reproduction is the process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves. Digital recording and reproduction converts the sound signal picked up by the microphone to a digital form by the process of digitization. This lets the audio data be stored and transmitted by a variety of media. Whereas successive copies of an analog recording tend to degrade in quality, as noise is added. A digital audio signal must be reconverted to analog form during playback before it is amplified and connected to a loudspeaker to produce sound, long before sound was first recorded on cylinders or records, music was recorded—first by written music notation, then also by mechanical devices. Fowler, this. cylinder with raised pins on the surface remained the device to produce and reproduce music mechanically until the second half of the nineteenth century. The Banu Musa brothers also invented an automatic flute player, which appears to have been the first programmable machine, according to Fowler, the automata were a robot band that performed. more than fifty facial and body actions during each musical selection. In the 14th century, Flanders introduced a mechanical bell-ringer controlled by a rotating cylinder, similar designs appeared in barrel organs, musical clocks, barrel pianos, and musical boxes. A music box is a musical instrument that produces sounds by the use of a set of pins placed on a revolving cylinder or disc so as to pluck the tuned teeth of a steel comb. They were developed from musical snuff boxes of the 18th century, some of the more complex boxes also have a tiny drum and/or bells, in addition to the metal comb. The fairground organ, developed in 1892, used a system of accordion-folded punched cardboard books, the player piano, first demonstrated in 1876, used a punched paper scroll that could store an long piece of music. The most sophisticated of the rolls were hand-played, meaning that the roll represented the actual performance of an individual. This technology to record a live performance onto a piano roll was not developed until 1904, piano rolls were in continuous mass production from 1896 to 2008. A1908 U. S. Supreme Court copyright case noted that, in 1902 alone, the use of piano rolls began to decline in the 1920s although one type is still being made today. The first device that could record actual sounds as they passed through the air was the phonautograph, the earliest known recordings of the human voice are phonautograph recordings, called phonautograms, made in 1857. They consist of sheets of paper with sound-wave-modulated white lines created by a stylus that cut through a coating of soot as the paper was passed under it
7.
Broadcasting
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Broadcasting began with AM radio, which came into popular use around 1920 with the spread of vacuum tube radio transmitters and receivers. Before this, all forms of communication were one-to-one, with the message intended for a single recipient. Over the air broadcasting is usually associated with radio and television, the receiving parties may include the general public or a relatively small subset, the point is that anyone with the appropriate receiving technology and equipment can receive the signal. The field of broadcasting includes both government-managed services such as radio, community radio and public television, and private commercial radio. The U. S. Code of Federal Regulations, title 47, part 97 defines broadcasting as transmissions intended for reception by the general public, private or two-way telecommunications transmissions do not qualify under this definition. For example, amateur and citizens band radio operators are not allowed to broadcast, as defined, transmitting and broadcasting are not the same. Transmissions using a wire or cable, like television, are also considered broadcasts. In the 2000s, transmissions of television and radio programs via streaming digital technology have increasingly been referred to as broadcasting as well, the earliest broadcasting consisted of sending telegraph signals over the airwaves, using Morse code, a system developed in the 1830s by Samuel F. B. Morse, physicist Joseph Henry and Alfred Vail and they developed an electrical telegraph system which sent pulses of electric current along wires which controlled an electromagnet that was located at the receiving end of the telegraph system. A code was needed to transmit natural language using only these pulses, Morse therefore developed the forerunner to modern International Morse code. Audio broadcasting began experimentally in the first decade of the 20th century, by the early 1920s radio broadcasting became a household medium, at first on the AM band and later on FM. Television broadcasting started experimentally in the 1920s and became widespread after World War II, satellite broadcasting was initiated in the 1960s and moved into general industry usage in the 1970s, with DBS emerging in the 1980s. Originally all broadcasting was composed of signals using analog transmission techniques but in the 2000s. In general usage, broadcasting most frequently refers to the transmission of information, Analog audio vs. HD Radio Analog television vs.9 zettabytes. This is the equivalent of 55 newspapers per person per day in 1986. Historically, there have been several methods used for broadcasting electronic media audio and/or video to the public, Telephone broadcasting. Telephone broadcasting also grew to include telephone services for news and entertainment programming which were introduced in the 1890s. These telephone-based subscription services were the first examples of electrical/electronic broadcasting, Radio broadcasting, audio signals sent through the air as radio waves from a transmitter, picked up by an antenna and sent to a receiver
8.
Radio
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When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form, Radio systems need a transmitter to modulate some property of the energy produced to impress a signal on it, for example using amplitude modulation or angle modulation. Radio systems also need an antenna to convert electric currents into radio waves, an antenna can be used for both transmitting and receiving. The electrical resonance of tuned circuits in radios allow individual stations to be selected, the electromagnetic wave is intercepted by a tuned receiving antenna. Radio frequencies occupy the range from a 3 kHz to 300 GHz, a radio communication system sends signals by radio. The term radio is derived from the Latin word radius, meaning spoke of a wheel, beam of light, however, this invention would not be widely adopted. The switch to radio in place of wireless took place slowly and unevenly in the English-speaking world, the United States Navy would also play a role. Although its translation of the 1906 Berlin Convention used the terms wireless telegraph and wireless telegram, the term started to become preferred by the general public in the 1920s with the introduction of broadcasting. Radio systems used for communication have the following elements, with more than 100 years of development, each process is implemented by a wide range of methods, specialised for different communications purposes. Each system contains a transmitter, This consists of a source of electrical energy, the transmitter contains a system to modulate some property of the energy produced to impress a signal on it. This modulation might be as simple as turning the energy on and off, or altering more subtle such as amplitude, frequency, phase. Amplitude modulation of a carrier wave works by varying the strength of the signal in proportion to the information being sent. For example, changes in the strength can be used to reflect the sounds to be reproduced by a speaker. It was the used for the first audio radio transmissions. Frequency modulation varies the frequency of the carrier, the instantaneous frequency of the carrier is directly proportional to the instantaneous value of the input signal. FM has the capture effect whereby a receiver only receives the strongest signal, Digital data can be sent by shifting the carriers frequency among a set of discrete values, a technique known as frequency-shift keying. FM is commonly used at Very high frequency radio frequencies for high-fidelity broadcasts of music, analog TV sound is also broadcast using FM. Angle modulation alters the phase of the carrier wave to transmit a signal
9.
Phonograph record
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The groove usually starts near the periphery and ends near the center of the disc. The phonograph disc record was the medium used for music reproduction until late in the 20th century. It had co-existed with the cylinder from the late 1880s. Records retained the largest market share even when new formats such as compact cassette were mass-marketed, by the late 1980s, digital media, in the form of the compact disc, had gained a larger market share, and the vinyl record left the mainstream in 1991. The phonograph record has made a resurgence in the early 21st century –9.2 million records were sold in the U. S. in 2014. Likewise, in the UK sales have increased five-fold from 2009 to 2014, as of 2017,48 record pressing facilities remain worldwide,18 in the United States and 30 in other countries. The increased popularity of vinyl has led to the investment in new, only two producers of lacquers remains, Apollo Masters in California, USA, and MDC in Japan. Vinyl records may be scratched or warped if stored incorrectly but if they are not exposed to heat or broken. The large cover are valued by collectors and artists for the space given for visual expression, in the 2000s, these tracings were first scanned by audio engineers and digitally converted into audible sound. Phonautograms of singing and speech made by Scott in 1860 were played back as sound for the first time in 2008, along with a tuning fork tone and unintelligible snippets recorded as early as 1857, these are the earliest known recordings of sound. In 1877, Thomas Edison invented the phonograph, unlike the phonautograph, it was capable of both recording and reproducing sound. Despite the similarity of name, there is no evidence that Edisons phonograph was based on Scotts phonautograph. Edison first tried recording sound on a paper tape, with the idea of creating a telephone repeater analogous to the telegraph repeater he had been working on. The tinfoil was wrapped around a metal cylinder and a sound-vibrated stylus indented the tinfoil while the cylinder was rotated. The recording could be played back immediately, Edison also invented variations of the phonograph that used tape and disc formats. A decade later, Edison developed a greatly improved phonograph that used a wax cylinder instead of a foil sheet. This proved to be both a better-sounding and far more useful and durable device, the wax phonograph cylinder created the recorded sound market at the end of the 1880s and dominated it through the early years of the 20th century. Berliners earliest discs, first marketed in 1889, but only in Europe, were 12.5 cm in diameter, both the records and the machine were adequate only for use as a toy or curiosity, due to the limited sound quality
10.
Sony
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Sony Corporation is a Japanese multinational conglomerate corporation that is headquartered in Kōnan, Minato, Tokyo. Its diversified business includes consumer and professional electronics, gaming, entertainment, the company is one of the leading manufacturers of electronic products for the consumer and professional markets. Sony was ranked 116th on the 2015 list of Fortune Global 500 and these make Sony one of the most comprehensive entertainment companies in the world. The group consists of Sony Corporation, Sony Pictures Entertainment, Sony Interactive Entertainment, Sony Music Entertainment, Sony Financial Holdings and others. Sony is among the Semiconductor sales leaders by year and as of 2013, the companys current slogan is BE MOVED. Their former slogans were make. believe, like. no. other, Sony has a weak tie to the SMFG keiretsu, the successor to the Mitsui keiretsu. Sony began in the wake of World War II, in 1946, Masaru Ibuka started an electronics shop in a department store building in Tokyo. The company had $530 in capital and a total of eight employees, in the following year he was joined by his colleague, Akio Morita, and they founded a company called Tokyo Tsushin Kogyo 東京通信工業. The company built Japans first tape recorder, called the Type-G, in 1958 the company changed its name to Sony. When Tokyo Tsushin Kogyo was looking for a name to use to market themselves, they strongly considered using their initials. The primary reason they did not is that the railway company Tokyo Kyuko was known as TTK, the company occasionally used the acronym Totsuko in Japan, but during his visit to the United States, Morita discovered that Americans had trouble pronouncing that name. Another early name that was tried out for a while was Tokyo Teletech until Akio Morita discovered that there was an American company already using Teletech as a brand name, the name Sony was chosen for the brand as a mix of two words. One was the Latin word sonus, which is the root of sonic and sound, and the other was sonny, a common slang term used in 1950s America to call a boy. In the 1950s Japan sonny boys, was a word into Japanese which connoted smart and presentable young men. The first Sony-branded product, the TR-55 transistor radio, appeared in 1955, at the time of the change, it was extremely unusual for a Japanese company to use Roman letters to spell its name instead of writing it in kanji. The move was not without opposition, TTKs principal bank at the time and they pushed for a name such as Sony Electronic Industries, or Sony Teletech. Akio Morita was firm, however, as he did not want the company tied to any particular industry. Eventually, both Ibuka and Mitsui Banks chairman gave their approval, according to Schiffer, Sonys TR-63 radio cracked open the U. S. market and launched the new industry of consumer microelectronics
11.
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
12.
Sticky-shed syndrome
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This deterioration renders the tape unusable. Some kinds of binder are known to break down over time, the symptoms of this breakdown can be immediately obvious even when rewinding the tape, tearing sounds and sluggish behavior. If a tape with sticky-shed syndrome is played, the reels will make screeching or squeaking sounds, in some cases, particularly with digital tapes, the symptoms are more subtle, causing intermittent dropouts. That binder contained polyurethane that soaks up water and causes the urethane to rise to the tapes surface and this problem became known as the sticky-shed syndrome. One explanation was offered that short strands of urethane were most commonly used in tapes - until it was discovered that middle-sized strands are better and were good at absorbing moisture. Baking the tape temporarily restores the tape by driving the water molecules from the binder so that it can be copied to another tape or a different format. After baking, the tape usually remains in condition for approximately a month. If the tape re-deteriorates, it may be possible to bake the tape again, many tapes affected by sticky-shed are those that were made by Ampex/Quantegy such as 406/407, 456/457,499, and consumer/audiophile grade back coated tapes such as Grand Master and 20-20+. Tapes made by Scotch/3M are also affected and the most common offenders here are the pro tapes such as 206/207, 226/227,808, though less common, many Sony branded tapes such as PR-150, SLH, ULH, and FeCr have also been reported to suffer from sticky-shed. Blank cassettes from the 70s-90s are unaffected because the binder was not used in cassette formulations. As of 2012, no documented or proven examples of sticky-shed from Maxell or TDK exist, there have been a few reports of some tape from the current manufacturers ATR and RMGI exhibiting symptoms of sticky-shed. But these may be isolated incidents relating to prototype or single bad batches, as of 2015 some 35mm magnetic fullcoat tapes produced by Kodak, such as those used for the audio portion of older IMAX films, are also reported to be exhibiting sticky-shed. As tapes remain in storage for a time, it is possible that other binder formulations may develop problems. Current solutions to sticky-shed syndrome seek to remove the unwanted moisture from the tape binder. Two different strategies are employed, applying heat to the tape. Baking is widely practiced, but can destroy tapes, while modification of humidity by safely controlling the environment may take significantly longer, its major benefit is that it does not irreparably damage the tape. Alternate practices have also developed by engineers to fix affected tapes. Baking is a practice for temporarily repairing sticky-shed syndrome
13.
Hydrolysis
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Hydrolysis usually means the cleavage of chemical bonds by the addition of water. When a carbohydrate is broken into its component sugar molecules by hydrolysis, generally, hydrolysis or saccharification is a step in the degradation of a substance. Hydrolysis can be the reverse of a reaction in which two molecules join together into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water, usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both substance and water molecule to split into two parts, in such reactions, one fragment of the target molecule gains a hydrogen ion. A common kind of hydrolysis occurs when a salt of an acid or weak base is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations, the salt also dissociates into its constituent anions and cations. For example, sodium acetate dissociates in water into sodium and acetate ions, sodium ions react very little with the hydroxide ions whereas the acetate ions combine with hydronium ions to produce acetic acid. In this case the net result is an excess of hydroxide ions. For example, dissolving sulfuric acid in water is accompanied by hydrolysis to give hydronium and bisulfate, for a more technical discussion of what occurs during such a hydrolysis, see Brønsted–Lowry acid–base theory. Acid–base-catalysed hydrolyses are very common, one example is the hydrolysis of amides or esters and their hydrolysis occurs when the nucleophile attacks the carbon of the carbonyl group of the ester or amide. In an aqueous base, hydroxyl ions are better nucleophiles than polar molecules such as water, in acids, the carbonyl group becomes protonated, and this leads to a much easier nucleophilic attack. The products for both hydrolyses are compounds with carboxylic acid groups, perhaps the oldest commercially practiced example of ester hydrolysis is saponification. It is the hydrolysis of a triglyceride with a base such as sodium hydroxide. During the process, glycerol is formed, and the fatty acids react with the base and these salts are called soaps, commonly used in households. In addition, in living systems, most biochemical reactions take place during the catalysis of enzymes, the catalytic action of enzymes allows the hydrolysis of proteins, fats, oils, and carbohydrates. As an example, one may consider proteases and they catalyse the hydrolysis of interior peptide bonds in peptide chains, as opposed to exopeptidases. However, proteases do not catalyse the hydrolysis of all kinds of proteins and their action is stereo-selective, Only proteins with a certain tertiary structure are targeted as some kind of orienting force is needed to place the amide group in the proper position for catalysis
14.
Tape head
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A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa. They can also be used to read credit/debit/gift cards because the strip of tape on the back of a credit card stores data the same way that other magnetic tapes do. Cassettes, reel-to-reel tapes, 8-tracks, VHS tapes, and even floppy disks and modern hard drive disks all use the principle of physics to store. The medium is magnetized in a pattern and it then moves at a constant speed over an electromagnet. Since the moving tape is carrying a changing magnetic field with it, it induces a voltage across the head. That voltage can then be amplified and connected to speakers in the case of audio, or measured and sorted into 1s, a head consists of a core of magnetic material arranged into a doughnut shape or toroid, into which a very narrow gap has been let. This gap is filled with a material, such as gold. This forces the magnetic flux out of the gap into the tape medium more than air would. The flux thus magnetises the tape at that point, while a head is reversible in principle, and very often in practice, there are desirable characteristics that differ between the playback and recording phases. One of these is the impedance of the coil - playback preferring a high impedance, in the very best tape recorders, separate heads are used to avoid compromising these desirable characteristics. Having separate heads for recording and playback has other advantages, such as off-tape monitoring during recording, the width of the head gap is also critical - the narrower the gap, the better the head will be - a narrow gap gives much better transcription in the magnetic domain. In this way, gaps of the order of micrometres are achievable, a record head, on the other hand, has a gap typically six times larger than that of the replay head, this gives a larger flux to magnetise the tape. The larger gap does not affect frequency response because the image is made by the trailing edge of the gap. A combined record/replay head has a compromise size gap typically three times that of a replay only head, there are also negative aspects of narrow head gaps, particularly for magnetic recording. The narrower the gap, the more bias signal must be used to maintain linearity of the signal on tape. This reduces high frequency headroom, particularly at lower tape speeds, manufacturers must find a compromise between intended tape speeds and head gaps for this reason. The physical design of a head depends on whether it is fixed or rotating, in either case, the face of the head where the gap is must be made hard wearing and highly smooth to avoid excessive head wear. It can also be seen due to the construction method of the head gap, head wear will tend to widen the gap
15.
Iron oxide
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Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides, common rust is a form of iron oxide. Iron oxides are used as inexpensive, durable pigments in paints, coatings. Colors commonly available are in the end of the yellow/orange/red/brown/black range. When used as a coloring, it has E number E172. Limonite Iron oxide nanoparticles List of inorganic pigments Information from Nano-Oxides, http, //chemed. chem. purdue. edu/demos/demosheets/12.3. html http, //minerals. usgs. gov/minerals/pubs/commodity/iron_oxide/ CDC - NIOSH Pocket Guide to Chemical Hazards de
16.
Chromium
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Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6 and it is a steely-grey, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word χρῶμα, chrōma, meaning color, Chromium metal is of high value for its high corrosion resistance and hardness. A major development was the discovery that steel could be highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating together comprise 85% of the commercial use, trivalent chromium ion is an essential nutrient in trace amounts in humans for insulin, sugar and lipid metabolism, although the issue is debated. While chromium metal and Cr ions are not considered toxic, hexavalent chromium is toxic and carcinogenic, abandoned chromium production sites often require environmental cleanup. Chromium is remarkable for its properties, it is the only elemental solid which shows antiferromagnetic ordering at room temperature. Above 38 °C, it changes to paramagnetic, Chromium metal left standing in air is passivated by oxidation, forming a thin, protective, surface layer. This layer is a structure only a few molecules thick. It is very dense, and prevents the diffusion of oxygen into the underlying metal and this is different from the oxide that forms on iron and carbon steel, through which elemental oxygen continues to migrate, reaching the underlying material to cause incessant rusting. Passivation can be enhanced by short contact with oxidizing acids like nitric acid, passivated chromium is stable against acids. Passivation can be removed with a reducing agent that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids, Chromium, unlike such metals as iron and nickel, does not suffer from hydrogen embrittlement. However, it suffer from nitrogen embrittlement, reacting with nitrogen from air. Chromium is the 22nd most abundant element in Earths crust with a concentration of 100 ppm. Chromium compounds are found in the environment from the erosion of chromium-containing rocks, Chromium is mined as chromite ore. About two-fifths of the ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan, although rare, deposits of native chromium exist
17.
Compact Cassette
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The Compact Cassette or Musicassette, also commonly called cassette tape, audio cassette, or simply tape or cassette, is an analog magnetic tape recording format for audio recording and playback. It was released by Philips in 1962, having developed in Hasselt. Compact cassettes come in two forms, either already containing content as a cassette, or as a fully recordable blank cassette. Its uses ranged from portable audio to home recording to data storage for early microcomputers, the first cassette player designed for use in car dashes was introduced in 1968. Between the early 1970s and the early 2000s, the cassette was one of the two most common formats for prerecorded music, first alongside the LP record and later the compact disc. Compact Cassettes contain two miniature spools, between which a magnetically coated, polyester-type plastic film is passed and wound and these spools and their attendant parts are held inside a protective plastic shell. This reversal is achieved either by flipping the cassette, or by having the machine itself change the direction of tape movement. In 1935, decades before the introduction of the Compact Cassette, AEG released the first reel-to-reel tape recorder and it was based on the invention of the magnetic tape by Fritz Pfleumer, which used similar technology but with open reels. These instruments were expensive and relatively difficult to use and were therefore used mostly by professionals in radio stations. In 1958, following four years of development, RCA Victor introduced the stereo, quarter-inch, reversible, however, it was a large cassette, and offered few pre-recorded tapes. Despite the multiple versions, it failed, consumer use of tape only took off in the early 1960s, after playback machines reached a comfortable, user-friendly design. This was achieved primarily by the introduction of transistors which replaced the bulky, fragile, reel-to-reel tape then became more suitable to household use, but still remained an esoteric product. The team at Philips was led by Lou Ottens in Hasselt, Philips was competing with Telefunken and Grundig in a race to establish its cassette tape as the worldwide standard, and it wanted support from Japanese electronics manufacturers. However, the Philips Compact Cassette became dominant as a result of Philips decision to license the format free of charge, Philips also released the Norelco Carry-Corder 150 recorder/player in the US in November 1964. By 1966 over 250,000 recorders had been sold in the US alone, by 1968,85 manufacturers had sold over 2.4 million players. By the end of the 1960s, the business was worth an estimated 150 million dollars. In the early years sound quality was mediocre, but it improved dramatically by the early 1970s when it caught up with the quality of 8-track tape, the Compact Cassette went on to become a popular alternative to the 12-inch vinyl LP during the late 1970s. The mass production of blank Compact Cassettes began in 1964 in Hanover, prerecorded music cassettes were launched in Europe in late 1965
18.
Fritz Pfleumer
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Fritz Pfleumer was a German-Austrian engineer who invented magnetic tape for recording sound. Fritz was born as the son of Robert and Minna, née Hünich and his father Robert was born in Greiz, and his mother Minna was born in Freiberg. Fritz had five siblings – Mimi, Hans, Hermann, Otto, Pfleumer developed a process for putting metal stripes on cigarette papers and reasoned that he could similarly coat a magnetic stripe to be used as an alternative to wire recording. In 1927, after experimenting with materials, Pfleumer used very thin paper that he coated with iron oxide powder using lacquer as glue. He received a patent in 1928, on 1 December 1932 Pfleumer granted AEG the right to use his invention when building the worlds first practical tape recorder, called Magnetophon K1. It was first demonstrated at the IFA in 1935
19.
Oberlin Smith
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Oberlin Smith was an American engineer who published one of the earliest works dealing with magnetic recording in 1888. He was born on March 22,1840 in Cincinnati, Ohio and he started a small machine shop in Bridgeton, New Jersey, where he lived most of his life, which became known as the Ferracute Machine Company in 1877. For the entire existence of the company he was the president and he died on July 19,1926 in New Jersey. Smith suggested using cotton or silk thread, into which steel dust or short clippings of fine wire could be suspended and these particles were to be magnetized in accordance with the alternating current from a microphone source. Smith also discussed the possibility of using a steel wire. A working unit was never built, many of Smiths ideas were used by Valdemar Poulsen when he developed the first true magnetic recorder. Recognition at the NJ Inventors Hall of Fame, compilation of Oberlin Smith biographical and technical information of his inventions
20.
Valdemar Poulsen
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Valdemar Poulsen was a Danish engineer who made significant contributions to early radio technology. He was born on 23 November 1869 in Copenhagen, the magnetic recording was demonstrated in principle as early as 1898 by Valdemar Poulsen in his telegraphone. Magnetic wire recording, and its successor, magnetic tape recording, an electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal. A playback head can then pick up the changes in the field from the tape. Poulsen obtained a Telegraphone Patent in 1898, and with his assistant, Peder O. Pedersen, later developed other magnetic recorders that recorded on steel wire, tape, or disks. None of these devices had electronic amplification, but the signal was easily strong enough to be heard through a headset or even transmitted on telephone wires. At the 1900 Worlds Fair in Paris, Poulsen had the chance to record the voice of Emperor Franz Josef of Austria which is believed to be the oldest surviving magnetic audio recording today. Poulsen developed an arc converter in 1908, referred to as the Poulsen Arc Transmitter, the system was able to communicate between Lyngby and Newcastle with a 100-foot mast. A stamp was issued in honor of Poulsen in 1969, the Valdemar Poulsen Gold Medal was awarded each year for outstanding research in the field of radio techniques and related fields by the Danish Academy of Technical Sciences. The award was presented on November 23, the anniversary of his birth, the award was discontinued in 1993. Timeline of historic inventions Sound recording List of people on stamps of Denmark 1898 –1998 Poulsens patent, ten-second video of the 1900 recording of the Austro-Hungarian emperor Franz Joseph on YouTube. Katz, Eugenii, Valdemar Poulsen at the Wayback Machine, Poulsen, Valdemar, US PAT No.661,619 Method of Recordings and Reproducing Sounds or Signals. 1900 World Exposition recording of Emperor Franz Joseph of Austria at the Wayback Machine by means of Poulsens telegraphone
21.
Iron(III) oxide
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Iron oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the two being iron oxide, which is rare, and iron oxide, which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the source of iron for the steel industry. Fe2O3 is ferromagnetic, dark red, and readily attacked by acids, Iron oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition. To a chemist, rust is considered a material, described as hydrated ferric oxide. Fe2O3 can be obtained in various polymorphs, in the main ones, α and γ, iron adopts octahedral coordination geometry. That is, each Fe center is bound to six oxygen ligands, α-Fe2O3 has the rhombohedral, corundum structure and is the most common form. It occurs naturally as the mineral hematite which is mined as the ore of iron. It is antiferromagnetic below ~260 K, and exhibits weak ferromagnetism between 260 K and the Néel temperature,950 K and it is easy to prepare using both thermal decomposition and precipitation in the liquid phase. Its magnetic properties are dependent on many factors, e. g. pressure, particle size and it is metastable and converted from the alpha phase at high temperatures. It occurs naturally as the mineral maghemite and it is ferromagnetic and finds application in recording tapes, although ultrafine particles smaller than 10 nanometers are superparamagnetic. It can be prepared by thermal dehydratation of gamma iron oxide-hydroxide, another method involves the careful oxidation of Fe3O4. The ultrafine particles can be prepared by decomposition of iron oxalate. Several other phases have been identified or claimed, the β-phase is cubic body centered, metastable, and at temperatures above 500 °C converts to alpha phase. It can be prepared by reduction of hematite by carbon, pyrolysis of iron chloride solution, the epsilon phase is rhombic, and shows properties intermediate between alpha and gamma, and may have useful magnetic properties. Preparation of the pure epsilon phase has proven challenging due to contamination with alpha. Material with a proportion of epsilon phase can be prepared by thermal transformation of the gamma phase. This phase is metastable, transforming to the alpha phase at between 500 and 750 °C
22.
AEG
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Allgemeine Elektricitäts-Gesellschaft AG was a German producer of electrical equipment founded as the Deutsche Edison-Gesellschaft für angewandte Elektricität in 1883 in Berlin by Emil Rathenau. After World War II its headquarters moved to Frankfurt am Main, in 1967 AEG joined with its subsidiary Telefunken AG creating Allgemeine Elektricitäts-Gesellschaft AEG-Telefunken. In 1985 Daimler-Benz purchased the AEG-Telefunken Aktiengesellschaft, which was renamed to AEG Aktiengesellschaft, the remains of AEG became part of Adtranz and Deutsche Aerospace. After acquiring the AEG household subsidiary AEG Hausgeräte GmbH in 1994, in 2005 Electrolux obtained the rights to the brand name AEG, the AEG name is also licensed to various brand partners under the Electrolux Global Brand Licensing programme. In 1883 Emil Rathenau founded Deutsche Edison-Gesellschaft für angewandte Elektricität in Berlin, initially producing electrical equipment, the company soon became involved in AC electric transmission systems. In 1907 Peter Behrens was appointed as consultant to AEG. This led to the creation of the initial corporate identity, with products. The company expanded in the first half of the 20th century, during the same period it entered the automobile and airplane markets. Electrical equipment for railways was produced during this time, beginning a history of supplying the German railways with electrical equipment. After WWII, the company lost its businesses in the part of Germany. After a merger in 1967 the company was renamed Allgemeine Elektricitäts-Gesellschaft AEG-Telefunken, the company experienced financial difficulties during the 1970s, resulting in the sale of some assets. In 1983 the consumer electronics division Telefunken Fernseh und Rundfunk GmbH was sold, under Daimler-Benz ownership, the former AEG companies eventually become part of the newly named Adtranz in 1995 and the AEG name was no longer used. Electrolux, which had acquired the household subsidiary AEG Hausgeräte GmbH of AEG in 1994. The company originated in 1882, when Emil Rathenau acquired licences to use some of Thomas Edisons lamp patents in Germany, the Deutsche Edison Gesellschaft was founded in 1883 with the financial backing of banks and private individuals, with Emil Rathenau as company director. In 1884, Munich-born engineer Oskar von Miller joined the executive board, the original factory was located near Stettiner Bahnhof. In 1887 the Company acquired land in the Berlin-Gesundbrunnen area on which the Weddingsche Maschinenfabrik was previously located, in the same year, in addition to a restructuring and expansion of the production range, the AEG name was adopted. In 1887 Mikhail Dolivo-Dobrowolsky joined the company as chief engineer, later becoming vice-director and his work on polyphase electric power led him to become the worlds leading engineer in three-phase electric power systems at the end of the 1880s. This success marked one of beginnings of the use of alternating current for electrification in Germany
23.
BASF
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BASF SE is a German chemical company and the largest producer in the world. Its headquarters is located in Ludwigshafen, Germany, BASF has customers in over 200 countries and supplies products to a wide variety of industries. Despite its size and global presence, BASF has received little public attention since abandoning its consumer product lines in the 1990s. At the end of 2015, the company employed more than 122,000 people, in 2015, BASF posted sales of €70.4 billion and income from operations before special items of about €6.7 billion. The company is expanding its international activities with a particular focus on Asia. Between 1990 and 2005, the company invested €5.6 billion in Asia, for example in sites near Nanjing and Shanghai, China, BASF is listed on the Frankfurt Stock Exchange, London Stock Exchange, and Zurich Stock Exchange. The company delisted its ADR from the New York Stock Exchange in September 2007, the company is a component of the Euro Stoxx 50 stock market index. BASF was founded on 6 April 1865 in Mannheim, in the German-speaking country of Baden by Friedrich Engelhorn and it had been responsible for setting up a gasworks and street lighting for the town council in 1861. The gasworks produced tar as a byproduct, and Engelhorn used this for the production of dyes, BASF was set up in 1865 to produce other chemicals necessary for dye production, notably soda and acids. In 1866 the dye production processes were also moved to the BASF site, BASF recruited Heinrich Caro, a German chemist with experience of the dyestuffs industry in England, to be the first head of research. Caro developed a synthesis for alizarin, and applied for a British patent on 25 June 1869, coincidentally Perkin applied for a virtually identical patent on 26 June 1869, and the two companies came to a mutual commercial agreement about the process. In 1901, some 80% of the BASF production was dyestuffs, sodium carbonate was produced by the Leblanc process until 1880, when the much cheaper Solvay process became available. BASF ceased to make its own and bought it from the Solvay company thereafter, sulfuric acid was initially produced by the lead chamber process, but in 1890 a unit using the contact process was brought on stream, producing the acid at higher concentration and at lower cost. This followed extensive research and development by Rudolf Knietsch, for which he received the Liebig Medal in 1904, BASF also acquired and began mining anhydrite for gypsum at the Kohnstein in 1917. In 1925, BASF merged with Bayer, Hoechst and three companies to form I. G. Farben played a role in the Nazi economy. During World War II, the company manufactured poison gas, Zyklon B, used at camps and employed forced. Several company directors and senior managers were tried for war crimes and crimes against humanity, as a result of this monopoly, BASF was able to start operations at a new site in Leuna in 1916, where explosives were produced during the First World War
24.
Tape bias
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Tape bias is the term for two techniques, AC bias and DC bias, that improve the fidelity of analogue magnetic tape sound recordings. DC bias is the addition of a current to the audio signal that is being recorded. AC bias is the addition of an inaudible high-frequency signal to the audio signal, magnetic tape without AC bias has a nonlinear response at low signal strengths, as measured by its coercivity. Bias increases the quality of most audio recordings significantly by pushing the signal into the linear zone of the tapes transfer function. Magnetic recording was proposed as early as 1888 by Oberlin Smith, by 1898 Valdemar Poulsen had demonstrated a magnetic recorder and proposed magnetic tape. The earliest magnetic recording systems simply applied the unadulterated input signal to a head, resulting in recordings with poor low-frequency response. Within short order, the addition of a direct current to the signal. The principal disadvantage of DC bias was that it left the tape with a net magnetization, Some early DC-bias systems used a permanent magnet that was placed near the record head. It had to be out of the way for replay. DC bias was replaced by AC bias but was later re-adopted by some very low-cost cassette recorders, although the improvements are marked with such DC bias, even more dramatic improvement results if an alternating-current bias is used instead. While several people around the world rediscovered AC bias, it was the German developments that were used in practice. The original patent for AC bias was filed by W. L. Carlson and Glenn L. Carpenter in 1921, the value of AC bias was somewhat masked by the primitive state of other aspects of magnetic recording, however, and Carlson and Carpenters achievement was largely ignored. Teiji Igarishi, Mokoto Ishikawa, and Kenzo Nagai of Japan published a paper on AC biasing in 1938, marvin Camras also rediscovered high-frequency bias independently in 1941 and received US2351004. The reduction in distortion and noise provided by AC bias was rediscovered in 1940 by Walter Weber, the German pair received several related patents, including DE743411 for high-frequency treatment of the sound carrier. Possibly independently of Weber and Braunmühl, the UK company Boosey & Hawkes produced a steel-wire recorder under government contract during the Second World War that was equipped with AC bias, examples still surface from time to time, many having been disposed of as government surplus stock. After the war, Boosey and Hawkes also produced a Reporter tape recorder in the early 1950s using magnetic tape, rather than wire, which was based on German wartime technology. The AC bias level is quite critical and, after being adjusted for a particular tape formulation with a recording machine, was usually left unchanged. A quantitative explanation of ac bias has been given by Bertram The characteristics of the system change quite markedly as the level of the bias current is changed
25.
Reel-to-reel audio tape recording
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Reel-to-reel or open-reel audio tape recording is the form of magnetic tape audio recording in which the recording medium is held on a reel, rather than being securely contained within a cassette. Reel-to-reel systems use a tape that is 1⁄4 inches in width and this compares to 0.15 inches wide and 1.875 inches per second for a cassette. By writing out the audio signal across more tape, reel-to-reel systems offer much higher fidelity. In spite of the tapes, less convenient use and generally higher cost media. Studer, Stellavox and Denon still produced reel to reel tape recorders in the 1990s, but as of 2014, only Nagra, Otari, originally, this format had no name, since all forms of magnetic tape recorders used it. The earliest machines produced distortion during the process which German engineers significantly reduced during the Nazi era by applying a bias signal to the tape. In 1939 one machine was found to make consistently better recordings than other ostensibly identical models, and when it was taken apart a minor flaw was noticed. It was introducing an AC signal to the tape, and this was adapted to new models using a high-frequency AC bias that has remained a part of audio tape recording to this day. American audio engineer Jack Mullin was a member of the U. S. Army Signal Corps during World War II and he acquired two Magnetophon recorders and 50 reels of I. G. Farben recording tape and shipped them home, over the next two years, he worked to develop the machines for commercial use, hoping to interest the Hollywood film studios in using magnetic tape for movie soundtrack recording. Crosby invested $50,000 in an electronics company, Ampex. Ampex went on to develop the first practical videotape recorders in the early 1950s to pre-record Crosbys TV shows, inexpensive reel-to-reel tape recorders were widely used for voice recording in the home and in schools before the Philips compact cassette, introduced in 1963, gradually took over. Cassettes eventually displaced reel-to-reel recorders for consumer use, however, the narrow tracks and slow recording speeds used in cassettes compromised fidelity. Columbia House carried pre-recorded reel-to-reel tapes from 1960 to 1984, even today, some artists of all genres prefer analog tapes musical, natural and especially warm sound. Due to harmonic distortion, bass can thicken up, creating a fuller-sounding mix, in addition, high end can be slightly compressed, which is more natural to the human ear. It is common for artists to record to digital and re-record the tracks to analog reels for this effect of natural sound. In addition to all of these attributes of tape, tape saturation is a form of distortion that many rock, blues. For the first time, audio could be manipulated as a physical entity, Tape editing is performed simply by cutting the tape at the required point, and rejoining it to another section of tape using adhesive tape, or sometimes glue
26.
Bandwidth (signal processing)
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Bandwidth is the difference between the upper and lower frequencies in a continuous set of frequencies. It is typically measured in hertz, and may refer to passband bandwidth, sometimes to baseband bandwidth. Passband bandwidth is the difference between the upper and lower frequencies of, for example, a band-pass filter, a communication channel. In the case of a filter or baseband signal, the bandwidth is equal to its upper cutoff frequency. A key characteristic of bandwidth is that any band of a given width can carry the amount of information. For example, a 3 kHz band can carry a telephone conversation whether that band is at baseband or modulated to some higher frequency, Bandwidth is a key concept in many telecommunications applications. In radio communications, for example, bandwidth is the range occupied by a modulated carrier signal. An FM radio receivers tuner spans a range of frequencies. A government agency may apportion the regionally available bandwidth to broadcast license holders so that their signals do not mutually interfere, each transmitter owns a slice of bandwidth. For different applications there are different precise definitions, which are different for signals than for systems. One definition of bandwidth, for a system, could be the range of frequencies over which the system produces a level of performance. A less strict and more practically useful definition will refer to the frequencies beyond which frequency response is small, small could mean less than 3 dB below the maximum value, or more rarely 10 dB below, or it could mean below a certain absolute value. As with any definition of the width of a function, many definitions are suitable for different purposes, in some contexts, the signal bandwidth in hertz refers to the frequency range in which the signals spectral density is nonzero or above a small threshold value. That definition is used in calculations of the lowest sampling rate that will satisfy the sampling theorem, the threshold value is often defined relative to the maximum value, and is most commonly the 3dB point, that is the point where the spectral density is half its maximum value. The word bandwidth applies to signals as described above, but it could apply to systems. To say that a system has a certain bandwidth means that the system can process signals of that bandwidth, or that the system reduces the bandwidth of a white noise input to that bandwidth. If the maximum gain is 0 dB, the 3 dB bandwidth is the range where the gain is more than −3 dB. This is also the range of frequencies where the gain is above 70. 7% of the maximum amplitude gain
27.
Bing Crosby
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Harry Lillis Bing Crosby, Jr. was an American singer and actor. The first multimedia star, from 1931 to 1954 Crosby was a leader in sales, radio ratings. His early career coincided with technical recording innovations such as the microphone and this allowed him to develop a laid-back, intimate singing style that influenced many of the popular male singers who followed him, including Perry Como, Frank Sinatra, Dick Haymes, and Dean Martin. Also in 1948, the Music Digest estimated that Crosby recordings filled more than half of the 80,000 weekly hours allocated to recorded radio music, in 1963, Crosby received the first Grammy Global Achievement Award. He is one of only 33 people to have three stars on the Hollywood Walk of Fame, in the categories of motion pictures, radio, Crosby influenced the development of the postwar recording industry. He became the first performer to pre-record his radio shows and master his commercial recordings onto magnetic tape. In addition to his work with early tape recording, he helped to finance the development of videotape, bought television stations, bred racehorses, Crosby died at the age of 74 on October 14,1977, from a sudden heart attack in Alcobendas, Spain. Crosby was born on May 2,1903 in Tacoma, Washington, in 1906, Crosbys family moved to Spokane, and in 1913, Crosbys father built a house at 508 E. Sharp Avenue. The house now sits on the campus of Crosbys alma mater Gonzaga University and he was the fourth of seven children, brothers Larry, Everett, Ted, and Bob, and two sisters, Catherine and Mary Rose. His parents were Harry Lowe Crosby, Sr. a bookkeeper, Crosbys mother was a second generation Irish-American. In 1910, seven-year-old Harry Crosby Jr. was forever renamed, the Sunday edition of the Spokesman-Review published a feature called The Bingville Bugle. Written by humorist Newton Newkirk, The Bingville Bugle was a parody of a hillbilly newsletter filled with gossipy tidbits, minstrel quips, creative spelling, and mock ads. A neighbor, 15-year-old Valentine Hobart, shared Crosbys enthusiasm for The Bugle, and noting Crosbys laugh, took a liking to him, eventually, the last vowel was dropped and the nickname stuck. Crosby later described Jolsons delivery as electric, Crosby graduated from Gonzaga High School in 1920 and enrolled at Gonzaga University. He attended Gonzaga for three years, but did not earn a bachelors degree, as a freshman, he played on the universitys baseball team. The university granted him a doctorate in 1937. In 1923, Crosby was invited to join a new band composed of school students a few years younger than himself. Al Rinker, Miles Rinker, James Heaton, Claire Pritchard and Robert Pritchard, along with drummer Crosby, formed the Musicaladers, the group performed on Spokane radio station KHQ, but disbanded after two years
28.
Ampex
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Ampex is an American electronics company founded in 1944 by Alexander M. Poniatoff. The name AMPEX is an acronym, created by its founder, at one time public, the remaining ongoing business unit was acquired by Delta Information Systems in October 2014, with the original parent, Ampex Corporation, ceasing operations in October 2014. Ampexs first great success was a line of tape recorders developed from the German wartime Magnetophon system at the behest of Bing Crosby. Ampex quickly became a leader in audio technology, developing many of the analog recording formats for both music and movies that remained in use into the 1990s. They also introduced multi-track recording, slow-motion and instant playback television, Ampexs tape business was rendered obsolete during the 1990s, and the company turned to digital storage products. They never managed to become a player in this field, russian inventor Alexander Matthew Poniatoff established the company in San Carlos, California, in 1944 as the Ampex Electric and Manufacturing Company. The name came from his initials plus ex to avoid using the name AMP already in use, during World War II, Ampex was a small manufacturer of high quality electric motors and generators for radars that used alnico 5 magnets from General Electric. Ampexs first offices were at 1313 Laurel St. San Carlos California, near the end of the war, while serving in the U. S. Army Signal Corps, Major Jack Mullin was assigned to investigate German radio and electronics experiments. He discovered the Magnetophons with AC biasing on a trip to Radio Frankfurt, the device produced much better fidelity than shellac records. Mullin acquired two Magnetophon recorders and 50 reels of BASF Type L tape, and brought them to America and he demonstrated them to the Institute of Radio Engineers in San Francisco on May 16,1946. Bing Crosby, a big star on radio at the time, was receptive to the idea of pre-recording his radio programs and he disliked the regimentation of live broadcasts, and much preferred the relaxed atmosphere of the recording studio. This may have been what Crosby was hoping to avoid, as that was the argument Crosby used with the network when he asked to use transcription disc recordings of his show. Those recordings were made directly from the live east coast show, in June 1947, Mullin, who was pitching the technology to the major Hollywood movie studios, got the chance to demonstrate his modified tape recorders to Crosby. When Crosby heard a demonstration of Mullins tape recorders, he saw the potential of the new technology. Ampex was finishing its prototype of the Model 200 tape recorder, after a successful test broadcast, ABC agreed to allow Crosby to pre-record his shows on tape. Crosby immediately appointed Mullin as his engineer and placed an order for $50,000 worth of the new recorders so that Ampex could develop a commercial production model from the prototypes. Crosby Enterprises was Ampexs West Coast representative until 1957, the companys first tape recorder, the Ampex Model 200A, was first shipped in April 1948. The first two units, serial numbers 1 and 2, were used to record the Bing Crosby Show
29.
Quadruplex videotape
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2-inch quadruplex videotape is the first practical and commercially successful analog recording videotape format. It was developed and released for the broadcast television industry in 1956 by Ampex, the first videotape recorder using this format was built and created in the same year. Broadcasters also sought a medium that was not as costly or time-consuming to edit. Faced with these challenges, broadcasters sought to adapt magnetic tape recording technology for use with television as well and this method was called quadrature scanning, as opposed to the helical scan transport used by later videotape formats. The cue track was used either as an audio track. A typical 4,800 ft reel of 2 in quad tape holds approximately one hour of recorded material at 15 inches per second, the quadruplex format employs segmented recording, each transversely recorded video track on a 2-inch quad videotape holds one-sixteenth or one-twentieth of a field of video. This meant that 2-inch quad did not support trick-play functions, such as still, shuttle, most quad machines made later in the 1960s and 1970s by Ampex could play back both low and high-band 2-inch quad tape. Time-shifting of television programming for the West Coast of the United States by the networks in the 1950s using kinescope films was quite a rushed and this usually meant the kinescope was aired almost immediately after it came straight out of the developing equipment, still warm from the film dryer. These were referred to by the networks as hot kines, by 1954, the networks used more raw film stock for kinescopes than all of the Hollywood film studios combined, spending up to $4,000 per half hour. They were desperate to obtain a quicker, less expensive, in the early 1950s, Ampex and several other companies such as Bing Crosby Enterprises and RCA were competing to release a videotape format. RCA and BCE did release working prototypes of their recorders, but their downfall was that all used a longitudinal method of recording. At the same time, the BBC developed a similar stationary-head video tape recorder system that saw some on-air use, starting in 1952, Ampex built the Mark I prototype VTR, using 2 in -wide tape. Ampex decided that instead of having the tape move fast across the head to record enough bandwidth for video and this resulted in the Mark I using arcuate scanning, which consisted of a spinning disk with a face which contacted the tape. This resulted in a track being recorded across the width of the tape. Ampex continued through the mid-1950s with the Mark II and Mark III prototype recorders, the Mark II used frequency modulation for recording video to tape, resulting in a much-improved, but still noisy, video image. The Mark III had improved signal-processing and servo electronics, resulting in much better video reproduction, the Mark III worked well, but its appearance was quite that of a prototype, and not a finished, saleable product. It was in a wooden case, with several parts of its chassis externally mounted in partially filled racks. Ampex then built the Mark IV by putting Mark III components into a sleek metal console, the Mark IV was the machine first publicly demonstrated at the National Association of Radio and Television Broadcasters convention in Chicago on April 14,1956
30.
VHS
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The Video Home System is a standard for consumer-level analog video recording on tape cassettes. Developed by Victor Company of Japan in the early 1970s, it was released in Japan in late 1976, from the 1950s, magnetic tape video recording became a major contributor to the television industry, via the first commercialized video tape recorders. At that time, the devices were used only in professional environments such as television studios. In the 1970s, videotape entered home use, creating the video industry and changing the economics of the television. The television industry viewed videocassette recorders as having the power to disrupt their business, in the 1980s and 1990s, at the peak of VHSs popularity, there were videotape format wars in the home video industry. Two of the formats, VHS and Betamax, received the most media exposure, VHS eventually won the war, dominating 60 percent of the North American market by 1980 and emerging as the dominant home video format throughout the tape media period. Optical disc formats later began to better quality than analog consumer video tape such as standard. The earliest of these formats, LaserDisc, was not widely adopted, however, after the introduction of the DVD format in 1997, VHSs market share began to decline. By 2008, DVD had replaced VHS as the preferred method of distribution. After several attempts by other companies, the first commercially successful VTR, at a price of US$50,000 in 1956, and US$300 for a 90-minute reel of tape, it was intended only for the professional market. Kenjiro Takayanagi, a broadcasting pioneer then working for JVC as its vice president, saw the need for his company to produce VTRs for the Japan market. In 1959, JVC developed a video tape recorder. In 1964, JVC released the DV220, which would be the companys standard VTR until the mid-1970s, in 1969 JVC collaborated with Sony Corporation and Matsushita Electric in building a video recording standard for the Japanese consumer. The effort produced the U-matic format in 1971, which was the first format to become a unified standard, U-matic was successful in business and some broadcast applications, but due to cost and limited recording time very few of the machines were sold for home use. Soon after, Sony and Matsushita broke away from the collaboration effort, Sony started working on Betamax, while Matsushita started working on VX. JVC released the CR-6060 in 1975, based on the U-matic format, Sony and Matsushita also produced U-matic systems of their own. In 1971, JVC engineers Yuma Shiraishi and Shizuo Takano put together a team to develop a consumer-based VTR, by the end of 1971 they created an internal diagram titled VHS Development Matrix, which established twelve objectives for JVCs new VTR. These included, The system must be compatible with any television set
31.
Helical scan
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Helical scan is a method of recording high frequency signals on magnetic tape. It is used in video tape recorders, video cassette recorders, digital audio tape recorders. In a fixed tape head recording system, magnetic tape is drawn past the head at a constant speed. The head creates a magnetic field in response to the signal to be recorded. As the tape moves away, the magnetic particles carry an imprint of the signal in their magnetic orientation. If the tape moves too slowly, a frequency signal will not be imprinted. Thus the bandwidth capacity of the recorded signal can be seen to be related to tape speed, the faster the speed. Digital video and digital audio need considerably more bandwidth than analog audio and this is impractical, since tapes of immense length would be required. The generally adopted solution is to rotate the head against the tape at high speed, so that the velocity is high. To accomplish this, the head must be tilted so that at each rotation of the head, each segment of the signal is recorded as a diagonal stripe across the tape. This is known as a helical scan because the tape wraps around the drum at an angle. The difference between the writing speed and linear tape speed is vast, for example,13 mph versus 35 mm/s. The helical scan method of recording was first developed by Eduard Schüller, with the advent of television broadcasting in Japan in the early 1950s, they saw the need for magnetic television signal recording just as engineers in the United States and Europe did. Thus, when tape motion was stopped, only a segment of the picture recording was present at the playback heads. The motivation to overcome this limitation led, in part, to the development of the helical scan system, toshiba introduced helical scan technology to the television industry in 1959. During the 1960s and 1970s, helical scan recording machines were introduced by many manufacturers and these factors also made it possible eventually to bring video recording to users at home, in a cassette format. There were a number of problems to be overcome with this system, the high tape/head speed could lead to rapid wear of both the tape and the head, so both need to be highly polished, and the head made of a hard, wear resistant material. Most systems operate with an air bearing separating the heads from the surface of the drum, supplying signals to a rotating head is also problematic, This is usually accomplished by coupling the signal inductively through a rotary transformer
32.
Videotape
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Videotape is magnetic tape used for storing video and usually sound in addition. Information stored can be in the form of either a signal or digital signal. Videotape is used in video tape recorders or, more commonly, videocassette recorders and camcorders. Videotapes are also used for storing scientific or medical data, such as the produced by an electrocardiogram. Tape is a method of storing information and thus imposes delays to access a portion of the tape that is not already under the heads. The early 2000s saw the introduction and rise to prominence of high quality video recording media such as hard disks. Since then, videotape has been relegated to archival and similar uses. The electronics division of entertainer Bing Crosbys production company, Bing Crosby Enterprises, overall the picture quality was still considered inferior to the best kinescope recordings on film. Bing Crosby Enterprises hoped to have a version available in 1954. The BBC experimented from 1952 to 1958 with a high-speed linear videotape system called VERA and it used half-inch tape traveling at 200 inches per second. RCA demonstrated the magnetic recording of both black-and-white and color television programs at its Princeton laboratories on December 1,1953. The high-speed longitudinal tape system, called Simplex, in development since 1951, could record, the color system used half-inch tape to record five tracks, one each for red, blue, green, synchronization, and audio. The black-and-white system used quarter-inch tape with two tracks, one for video and one for audio, both systems ran at 360 inches per second. RCA-owned NBC first used it on The Jonathan Winters Show on October 23,1956 when a song sequence by Dorothy Collins in color was included in the otherwise live television program. BCE demonstrated a color system in February 1955 using a longitudinal recording on half-inch tape. CBS, RCAs competitor, was about to order BCE machines when Ampex introduced the superior Quadruplex system, BCE was acquired by 3M Company in 1956. Quad employed a transverse four-head system on a tape. On January 22,1957, the NBC Television game show Truth or Consequences, produced in Hollywood, Ampex introduced a color videotape recorder in 1958 in a cross-licensing agreement with RCA, whose engineers had developed it from an Ampex black-and-white recorder
33.
Videocassette recorder
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Use of a VCR to record a television program to play back at a more convenient time is commonly referred to as timeshifting. VCRs can also play back prerecorded tapes, in the 1980s and 1990s, prerecorded videotapes were widely available for purchase and rental, and blank tapes were sold to make recordings. These features began as simple mechanical counter-based single-event timers, but were replaced by more flexible multiple-event digital clock timers. In later models the multiple timer events could be programmed through a menu interface displayed on the playback TV screen and this feature allowed several programs to be recorded at different times without further user intervention, and became a major selling point. The history of the recorder follows the history of videotape recording in general. Ampex introduced the Quadruplex videotape professional broadcast standard format with its Ampex VRX-1000 in 1956 and it became the worlds first commercially successful videotape recorder using two-inch wide tape. Due to its price of US$50,000, the Ampex VRX-1000 could be afforded only by the television networks. In 1959 Toshiba announced a new method of recording known as helical scan, first implemented in reel-to-reel videotape recorders, the Telcan, produced by the UK Nottingham Electronic Valve Company in 1963, was the first home video recorder. It could be bought as a unit or in kit form for £60, however, there were several drawbacks, it was expensive, not easy to assemble, and could only record 20 minutes at a time. It recorded in black-and-white, the format available in the UK at the time. The half-inch tape Sony model CV-2000, first marketed in 1965, was their first VTR intended for home use, Ampex and RCA followed in 1965 with their own reel-to-reel monochrome VTRs priced under US$1,000 for the home consumer market. The EIAJ format was a standard format used by various manufacturers. EIAJ-2 used a cartridge that contained a supply reel, the reel was part of the recorder, and the tape had to be fully rewound before removing the cartridge. In 1972, videocassettes of movies became available for home use, Sony demonstrated a videocassette prototype in October 1969, then set it aside to work out an industry standard by March 1970 with seven fellow manufacturers. The result, the Sony U-matic system, introduced in Tokyo in September 1971, was the worlds first commercial videocassette format. Its cartridges, resembling larger versions of the later VHS cassettes, used 3/4-inch tape and had a playing time of 60 minutes. Sony also introduced two machines to use the new tapes, U-matic, with its ease of use, quickly made other consumer videotape systems obsolete in Japan and North America, where U-matic VCRs were widely used by television newsrooms schools and businesses. But the high cost - US$1,395 in 1971 for a combination TV/VCR, in 1970, Philips developed a home video cassette format specially made for a TV station in 1970 and available on the consumer market in 1972
34.
Optical disc
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The encoding material sits atop a thicker substrate which makes up the bulk of the disc and forms a dust defocusing layer. The encoding pattern follows a continuous, spiral path covering the disc surface. Most optical discs exhibit a characteristic iridescence as a result of the diffraction grating formed by its grooves and this side of the disc contains the actual data and is typically coated with a transparent material, usually lacquer. The reverse side of a disc usually has a printed label, sometimes made of paper. Optical discs are usually between 7.6 and 30 cm in diameter, with 12 cm being the most common size, a typical disc is about 1.2 mm thick, while the track pitch ranges from 1.6 µm to 320 nm. An optical disc is designed to support one of three recording types, read-only, recordable, or re-recordable, write-once optical discs commonly have an organic dye recording layer between the substrate and the reflective layer. Rewritable discs typically contain an alloy recording layer composed of a phase change material, most often AgInSbTe, an alloy of silver, indium, antimony, Optical discs are most commonly used for storing music, video, or data and programs for personal computers. The Optical Storage Technology Association promotes standardized optical storage formats, although optical discs are more durable than earlier audio-visual and data storage formats, they are susceptible to environmental and daily-use damage. Libraries and archives enact optical media preservation procedures to ensure continued usability in the optical disc drive or corresponding disc player. For computer data backup and physical data transfer, optical discs such as CDs and DVDs are gradually being replaced with faster, smaller solid-state devices and this trend is expected to continue as USB flash drives continue to increase in capacity and drop in price. Additionally, music purchased or shared over the Internet has significantly reduced the number of audio CDs sold annually. The first recorded use of an optical disc was in the 1884 when Alexander Graham Bell, Chichester Bell. An early optical disc system existed in 1935, named Lichttonorgel, an early analog optical disc used for video recording was invented by David Paul Gregg in 1958 and patented in the US in 1961 and 1969. This form of optical disc was an early form of the DVD. It is of special interest that U. S, patent 4,893,297, filed 1989, issued 1990, generated royalty income for Pioneer Corporations DVA until 2007 —then encompassing the CD, DVD, and Blu-ray systems. In the early 1960s, the Music Corporation of America bought Greggs patents and his company, american inventor James T. Russell has been credited with inventing the first system to record a digital signal on an optical transparent foil which is lit from behind by a high-power halogen lamp. Russells patent application was first filed in 1966 and he was granted a patent in 1970, following litigation, Sony and Philips licensed Russells patents in the 1980s. Both Greggs and Russells disc are floppy media read in transparent mode, in the Netherlands in 1969, Philips Research physicist, Pieter Kramer invented an optical videodisc in reflective mode with a protective layer read by a focused laser beam U. S
35.
Digital video recorder
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A digital video recorder is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to disk recording, portable media players and TV gateways with recording capability, and digital camcorders. Personal computers are connected to video capture devices and used as DVRs. Many DVRs are classified as electronic devices, such devices are sometimes referred to as personal video recorders. Consumer digital video recorders ReplayTV and TiVo were launched at the 1999 Consumer Electronics Show in Las Vegas, Microsoft also demonstrated a unit with DVR capability, but this did not become available until the end of 1999 for full DVR features in Dish Networks DISHplayer receivers. TiVo shipped their first units on March 31,1999, ReplayTV won the Best of Show award in the video category with Netscape co-founder Marc Andreessen as an early investor and board member, but TiVo was more successful commercially. Many DVRs use the MPEG format for compressing the digital video, video recording capabilities have become an essential part of the modern set-top box, as TV viewers have wanted to take control of their viewing experiences. Digital video recorders tied to a video service At the 1999 CES, which also included WebTV Networks internet TV. By the end of 1999 the Dishplayer had full DVR capabilities and within a year, in the UK, digital video recorders are often referred to as plus boxes. Freeview+ have been around in the UK since the late 2000s, british Sky Broadcasting markets a popular combined receiver and DVR as Sky+. TiVo launched a UK model in 2000, and is no longer supported, except for third party services, south African based Africa Satellite TV beamer Multichoice recently launched their DVR which is available on their DStv platform. Astro introduced their DVR system, called Astro MAX, which was the first PVR in Malaysia but was phased out two years after its introduction. In the case of television, there is no encoding necessary in the DVR since the signal is already a digitally encoded MPEG stream. The digital video recorder simply stores the digital stream directly to disk and it can, however, also force the manufacturer to implement non-skippable advertisements and automatically expiring recordings. The overall net effect on video recorders and related technology is unlikely to be substantial as standalone DVRs are currently readily available on the open market. In 2003 many Satellite and Cable providers introduced dual-tuner digital video recorders, in the UK, BSkyB introduced their first PVR Sky+ with dual tuner support in 2001. These machines have two independent tuners within the same receiver, kogan. com introduced a dual-tuner PVR in the Australian market allowing free-to-air television to be recorded on a removable hard drive. Some dual-tuner DVRs also have the ability to output to two television sets at the same time
36.
Random access
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It is typically contrasted to sequential access. For example, data might be stored notionally in a sequence like a row. However, given all the coordinates, a program can access each record about as quickly and easily as any other, at first the term random access was used because the process had to be capable of finding records no matter in which sequence they were required. However, soon the term direct access gained favour because one could directly retrieve a record, the operative attribute however is that the device can access any required record immediately on demand. The opposite is sequential access, where a remote element takes longer time to access, a typical illustration of this distinction is to compare an ancient scroll and the book. A more modern example is a tape and a CD. In data structures, direct access implies the ability to access any entry in a list in constant time, very few data structures can guarantee this, other than arrays. Direct access is required, or at least valuable, in many such as binary search. Other data structures, such as linked lists, sacrifice direct access to permit efficient inserts, deletes, data stream Random-access machine Locality of reference
37.
Magnetic tape data storage
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Magnetic tape data storage is a system for storing digital information on magnetic tape using digital recording. Modern magnetic tape is most commonly packaged in cartridges and cassettes, the device that performs writing or reading of data is a tape drive. Autoloaders and tape libraries automate cartridge handling, for example, a common cassette-based format is Linear Tape-Open, which comes in a variety of densities and is manufactured by several companies. Sony announced in 2014 that they had developed a storage technology with the highest reported magnetic tape data density,148 Gbit/in². Initially, magnetic tape for storage was wound on 10. 5-inch reels. This de facto standard for computer systems persisted through the late 1980s. Tape cartridges and cassettes were available as early as the mid-1970s and were used with small computer systems. With the introduction of the IBM3480 cartridge in 1984, large computer systems started to move away from open reel tapes, magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The UNISERVO drive recording medium was a metal strip of 0. 5-inch wide nickel-plated phosphor bronze. Recording density was 128 characters per inch on eight tracks at a speed of 100 in/s. Of the eight tracks, six were data, one was a parity track, making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second. A small reel of mylar tape provided separation from the metal tape, IBM computers from the 1950s used ferrous-oxide coated tape similar to that used in audio recording. IBMs technology soon became the de facto industry standard, magnetic tape dimensions were 0. 5-inch wide and wound on removable reels up to 10.5 inches in diameter. Different tape lengths were available with 1,200 feet and 2,400 feet on mil, during the 1980s, longer tape lengths such as 3,600 feet became available using a much thinner PET film. Most tape drives could support a maximum size of 10.5 inches. CDC used IBM compatible 1/2 inch magnetic tapes, but also offered a 1 inch wide variant, a so-called mini-reel was common for smaller data sets, such as for software distribution. These were 7-inch reels, often with no fixed length—the tape was sized to fit the amount of data recorded on it as a cost-saving measure. Early IBM tape drives, such as the IBM727 and IBM729, were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long u-shaped loops of tape
38.
UNIVAC I
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The UNIVAC I was the first commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, design work was started by their company, Eckert–Mauchly Computer Corporation, and was completed after the company had been acquired by Remington Rand. In the years before successor models of the UNIVAC I appeared, the first Univac was accepted by the United States Census Bureau on March 31,1951, and was dedicated on June 14 that year. The fifth machine was used by CBS to predict the result of the 1952 presidential election, with a sample of just 1% of the voting population it famously predicted an Eisenhower landslide while the conventional wisdom favored Stevenson. As such the UNIVAC competed directly against punch-card machines, though the UNIVAC originally could neither read nor punch cards and that shortcoming hindered sales to companies concerned about the high cost of manually converting large quantities of existing data stored on cards. This was corrected by adding offline card processing equipment, the UNIVAC Card to Tape converter, however, the early market share of the UNIVAC I was lower than the Remington Rand Company wished. To promote sales, the company joined with CBS to have UNIVAC I predict the result of the 1952 Presidential election, UNIVAC I predicted Eisenhower would have a landslide victory over Adlai Stevenson whom the pollsters favored. The result was a public awareness of computing technology. The first contracts were with government agencies such as the Census Bureau, the U. S. Air Force, contracts were also signed by the ACNielsen Company, and the Prudential Insurance Company. Following the sale of Eckert–Mauchly Computer Corporation to Remington Rand, due to the cost overruns on the project, Remington Rand convinced Nielsen and Prudential to cancel their contracts. The first sale, to the Census Bureau, was marked with a ceremony on March 31,1951, at the Eckert–Mauchly Divisions factory at 3747 Ridge Avenue. As a result, the first installation was with the second computer, UNIVAC installations, 1951–1954 Originally priced at US$159,000, the UNIVAC I rose in price until they were between $1,250,000 and $1,500,000. A total of 46 systems were built and delivered. The UNIVAC I was too expensive for most universities, and Sperry Rand, a few UNIVAC I systems stayed in service long after they were made obsolete by advancing technology. The Census Bureau used its two systems until 1963, amounting to 12 and nine years of service, respectively, Sperry Rand itself used two systems in Buffalo, New York until 1968. The insurance company Life and Casualty of Tennessee used its system until 1970, UNIVAC I used 5,000 vacuum tubes, weighed 16,000 pounds, consumed 125 kW, and could perform about 1,905 operations per second running on a 2.25 MHz clock. The Central Complex alone was 4.3 m by 2.4 m by 2.6 m high, the complete system occupied more than 35.5 m² of floor space. The main memory consisted of 1000 words of 12 characters, when representing numbers, they were written as 11 decimal digits plus sign
39.
9 track tape
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The IBM System/360, released in 1964, introduced what is now generally known as 9 track tape. Data is stored as 8-bit characters, spanning the width of the tape. Various recording methods were employed during its lifetime as tape speed and data density increased, including PE, GCR, tapes came in various sizes up to 3,600 feet in length. The standard size of a byte was effectively set at eight bits with the S/360, the control electronics would then indicate to the controlling computer that the unit was ready for operation. Like its audio counterpart, moving tape past the heads on nine-track digital required precise control. The capstan motor was designed for smooth operation. Feedback to the electronics was accomplished by a tachometer, usually an optical tone wheel. Starting and stopping the capstan was controlled by ramp generators to ensure a properly sized inter-record gap, the vacuum columns were chambers open at one end, the openings being in line with the tape path before and after the capstan and roller assemblies. The amount of tape in the column was controlled by four optical or vacuum sensors on the sides of the columns. The control electronics kept the curve of the loop between the two inner sensors, cueing the supply reel to feed more or the take-up reel to take more as necessary. Tape motion on many systems was bidirectional, i. e. tape could be either forward or backward at the request of the controlling computer. Because the supply vacuum column kept a small, constant tension in the reverse direction, unlike most audio tape systems, the capstan and head assemblies were always in contact with the tape, even during fast forward and rewind operations. Tapes included an end-of-tape foil strip, when EOT was encountered while writing, the computer program would be notified of the condition. This gave the program a chance to write information on the tape while there was still enough tape to do so. The sensing of BOT and EOT was achieved by shining a small lamp at the surface at an oblique angle. When the foil strip moved past the lamp a photo-receptor would see the flash of light. This is the reason that photographic flash cameras were not allowed in data centers since they could trick the tape drives into falsely sensing BOT and EOT. The above describes a typical system, however, manufacturers engineered many alternative designs
40.
IBM 7 track
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IBMs first magnetic tape data storage devices, introduced in 1952, use what is now generally known as 7 track tape. The magnetic tape is 1/2 wide and there are six tracks plus one parity track for a total of seven parallel tracks that span the length of the tape. Data is stored as six-bit characters, with bit of the character. These tape drives were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long U-shaped loops of tape, between active control of powerful reel motors and vacuum control of these U-shaped tape loops, extremely rapid start and stop of the tape at the tape-to-head interface could be achieved. When active, the two tape reels thus fed tape into or pulled out of the vacuum columns, intermittently spinning in rapid. Stock shots of such vacuum-column tape drives in motion were used to represent the computer in films. Density Initial recording density was 100 characters per inch, later models supported 200,556 and 800 characters per inch. Inter-record Gap A gap between records allowed the time to start and stop the tape. Latency There was only a 1. 5ms delay for the tape to reach its full reading or writing speed. Markers Aluminum strips were glued several feet from the ends of the tape to serve as logical beginning, write protection A removable plastic ring in the back of the tape reel was inserted to indicate writing should be permitted. The IBM726 dual magnetic tape reader/recorder for the IBM701 was announced on May 21,1952, the IBM727 Magnetic Tape Unit was announced for the IBM701 and IBM702 on September 25,1953. It became IBMs standard tape drive for their vacuum tube era computer systems and it was withdrawn on May 12,1971. The IBM728 magnetic tape drive was used on the SAGE AN/FSQ-7 computer and it was physically similar to the IBM727, but with significantly different specifications. Tracks,6 Data,1 synchronization words,6 chars words/inch,41.33 The IBM729 Magnetic Tape Unit was IBMs iconic tape mass storage system from the late 1950s through the mid-1960s and it was used on late 700, most 7000 and many 1400 series computers. A new dual gap head assembly allowed read-after-write verification, the IBM7330 Magnetic Tape Unit was a low cost slower tape system. It was common on 1400 series computers, the 2400 Series Magnetic Tape Units were introduced with the System/360. Most were IBM9 Track format drives, but they could be ordered with seven-track read/write heads, allowing them to read and write seven-track tapes
41.
Quarter-inch cartridge
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Quarter inch cartridge tape is a magnetic tape data storage format introduced by 3M in 1972, with derivatives still in use as of 2016. QIC comes in a rugged enclosed package of aluminum and plastic that holds two tape reels driven by a belt in direct contact with the tape. The tape was originally 1⁄4-inch wide and anywhere from 300 to 1,500 feet long, since the introduction of QIC, it has been widely used and many variations exist. There is a QIC trade association that publishes QIC standards which include interfaces, to a very large extent it was the efficiency and openness of this organization which encouraged hardware and software developers to use this type of drive and media. The QIC cartridge is distinguished from other types of cartridges by the fact that it contains an endless drive belt which is moved at a uniform speed by a motorised capstan. Since the belt is in contact with the tape, this ensures both that the moves at uniform speed, and that neutral tension is maintained at all times. This is in contrast to cassette tapes or DATs where the tape is moved past the head by a capstan and pinch wheel, the tape in a QIC cartridge is not physically attached to the reels and is never completely unwound. This is again different from other cassettes or cartridges, which generally have some form of clip anchoring on at least one end of the tape. To ensure that the tape is never completely unwound, each end has a beginning or end of tape hole which is detected by an optical sensor. If a defective drive—for example with fluff in a sensor—winds the tape past the BOT or EOT marker, the tape will detach from the spool, however, because the tape is belt-driven, seeking back and forth can eventually cause the tape to become unevenly tensioned. It is therefore necessary to periodically retension the cartridge and this is accomplished by winding the tape from beginning to end and back in one operation, allowing the belt to equalize itself. For newer QIC drives that use a SCSI interface, there is a SCSI RETENSION command to do this, when the cartridge gets old, the belt may not provide enough friction to turn the takeup spool smoothly. When this happens, the tape will need to be replaced, in some cases a cartridge must be formatted before use. The capability to do this is in the rather than the host computer. The first QIC tape format was the 5.875 in by 3.875 in Data Cartridge format with two internal belt-driven reels and a metal base. The original product, the DC300, has 300 feet of tape and holds 200 kilobytes. 35GB on a DC9135 cartridge Other QIC DC standards include the QIC-02, later QIC DC drives usually use the SCSI interface. Later, the smaller Minicartridge form-factor was introduced and this is 2.375 in by 3.125 in size and is small enough to fit in a 3.5 in drive bay. Travan is an evolution of the QIC Minicartridge format, sold for computer use
42.
Kansas City standard
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The Kansas City standard, or Byte standard, is a digital data format for audio cassette drives. Although the standard had existed from the earliest days of the microcomputer revolution, early microcomputers generally used punched tape for program storage, an expensive option. Computer consultant Jerry Ogdin conceived the use of tones on a cassette to replace the paper tapes. He took the idea to Les Solomon, editor of Popular Electronics magazine, in September 1975 the two co-authored an article on the HITS, using two tones to represent 1s and 0s. Soon after a number of manufacturers started using similar approaches, although each of these systems were incompatible, wayne Green, who had just started Byte magazine, wanted all the manufacturers to get together and produce a single cassette standard. The site picked was Kansas City, Missouri, the two-day meeting was attended by 18 people who settled on a system based on Don Lancasters design, published in Byte magazines first issue. After the meeting, Lee Felsenstein and Harold Mauch wrote the standard, a cassette interface is similar to a modem connected to a serial port. The 1s and 0s from the port are converted to audio tones using audio frequency-shift keying. A0 bit is represented as four cycles of a 1200 Hz sine wave, and this gives a data rate of 300 baud. Each frame starts with one start bit followed by eight data bits followed by two stop bits, so each frame is 11 bits, for a data rate of 27 3⁄11 bytes per second. The February 1976 issue of Byte had a report on the symposium, the 300 baud rate was reliable but slow. Most audio cassette circuits would support higher speeds, according to Solomon, the efforts were unsuccessful, Unfortunately, it didnt last long, before the month ended, everyone went back to his own tape standard and the recording confusion got worse. The participants of the Kansas City symposium include the following and they provided the S-100 bus CUTS Tape I/O interface board which offers both CUTS and Kansas City standard support to any S-100 system. Processor Technology provided an 8080 program to be recorded and this test record did not work and Processor Technology was unable to devote more time to the effort. Daniel Meyer and Gary Kay of Southwest Technical Products arranged for Robert Uiterwyk to provide his 4K BASIC interpreter program for the 6800 microprocessor, the idea was to record the program on audio tape in the Kansas City standard format and then make a master record from the tape. Eva-Tone made Soundsheets on thin vinyl that would hold one song and these were inexpensive and could be bound in a magazine. Bill Turner and Bill Blomgren of MicroComputerSystems Inc. along with Bob Jones of Interface Age and Bud Schamburger of Holiday Inn worked with EVA-TONE, the intermediate stage of recording to tape produced dropouts so a SWTPC AC-30 cassette interface was connected directly to the record cutting equipment. The May 1977 issue of Interface Age contains the first Floppy ROM, the September 1978 Floppy ROM Number 5 has two sides, Apple BASIC the automated dress pattern and IAPS format A program for writing letters
43.
Tarbell Cassette Interface
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The Tarbell Cassette Interface is an expansion card for use with the Altair 8800 early personal computer, or other systems using the Altairs S-100 bus. It was designed by Don Tarbell and sold by Tarbell Electronics as early as 1976, at the time, it was considered to be fast, reliable, and popular. While supporting the 1975 Kansas City standard, it introduced a much faster Tarbell standard which became a de facto standard for compact cassette data storage. Tarbell also sold products, including TARBELL CASSETTE BASIC in 1978. The latter includes a Tarbell floppy disk interface, said to plug into any S-100 bus computer, the Tarbell Cassette Interface Manual The board that launched the company and made Tarbell a household word in the world of the S-100 bus s100computers. com Tarbell S-100 boards and docs
