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The History of Magnetic Recording



The History of Magnetic Recording by Steven Schoenherr, University of San Diego, Nov. 5, 2002

The history of magnetic recording began with the telegraph. When Samuel F. B. Morse sent an electrical signal for "What hath God wrought!" over a wire from Washington to Baltimore in 1844, he created a new technology and industry. Over the years, inventors sought to improve the telegraph. Alexander Graham Bell at the 1876 World's Fair in Philadelphia unveiled to the public a device that for the first time turned mechanical sound waves into electrical current and back again. He spoke into a microphone and his voice came out from a vibrating diaphragm speaker. The telephone was an instant success, won a prize at the Fair, launched what would become the world's largest communication company, and influenced countless others to improve the technology of sound recording. Thomas Edison was influenced by Bell's work to create the cylinder phonograph in 1877. When Oberlin Smith visited Edison's lab at Menlo Park NJ in early 1878, he was inspired to improve the phonograph by a different method, using a magnetizing coil to record sound on wire rather than Edison's method of using a needle to etch a wavy groove on a wax cylinder. He did not succeed, but wrote an accurate description in a memorandum Sept. 23, 1878, and wrote an article for Electrical World in Sept. 1888 that was also published in French by La Lumiere Electrique. The idea was in the air. (1)

Valdemar Poulsen in Denmark would succeed in 1898 where Smith had failed. He built and patented the first working magnetic recorder called the Telegraphone Poulsen had become a telephone engineer at the Copenhagen Telephone Company in 1893 and began to experiment with magnetism to record telephone messages. By 1899 he filed U.S. patent 661,619 for a vertical wire-covered cylinder, and in 1900 demonstrated improved drum and horizontal wire cylinder models at the 1900 Paris Exhibition. While making these improved models, Poulsen and his partner Peder O. Pedersen discovered the application of a direct current to the recording head, called dc bias, and improved the sound quality on a steel tape version of the Telegraphone. At the Paris fair, Poulsen recorded the voice of Emperor Franz Joseph, today preserved in the Danish Museum of Science and Technology as the oldest magnetic sound recording. Poulsen stopped his work on magnetic recording and turned to radio after 1902, and only a small number of his machines were made in Denmark and Germany. The American Telegraphone Company acquired the patent rights in 1905 and made dictating machines, selling 50 to the Du Pont Company. However, the signal remained weak without amplification and the wire spools became twisted and were unreliable. The wax cylinder phonographs of the rival Ediphone and Dictaphone companies were cheaper and more reliable. By 1918, the company went into receivership and stopped manufacturing after 1924. (2)

The U. S. Navy discovered a new use for the Telegraphone in World War I. In 1914 Germany used wire recorders purchased from the American Telegraphone Company to transmit high-speed wireless telegraph messages to German submarines in the Atlantic. Only another Telegraphone operating at high speed could record the messages and make them intelligible at a slower speed. Charles Apgar, an employee of the American Marconi Company, was operating an amateur radio station W2MN and had developed an amplifier using a DeForest Audion tube. He picked up the German radio transmissions, amplified them through a loudspeaker and recorded them on Dictaphone cylinders and gave them to the government. Secretary of the Navy Josephus Daniels ordered the Navy to seize the German radio station in Sayville NY on July 8, 1915, to stop the use of its Telegraphones by German spies. The Naval Research Laboratory in Washington began research on magnetic recording with 4 Telegraphones purchased from the American Telegraphone Company. In 1921 W. L. Carlson and Glenn L. Carpenter filed for patent 1,640,881 on the application of ac bias to the record head to improve the quality of telegraph signals. But as Poulsen had discovered, magnetic recording was not yet practical and ac bias would be forgotten when the Navy ended its experiments. (3)

Magnetic recording was improved in Germany after World War I. Kurt Stille had bought a Telegraphone in 1903 for his experiments, and by 1924 began sales of an improved wire recorder with an electronic amplifier to be used as a dictation machine. In 1928 he formed the Echophone Company with Karl Bauer and contracted with Ferdinand Schuchard AG and its talented engineer Semi Begun to manufacture the Dailygraph, the first cassette magnetic recorder. In 1932 International Telephone and Telegraph bought Stille's companies and merged them into C. Lorenz AG. Begun developed the Textophone dictation machine in 1933 and the Lorenz company sold thousands to Hitler's Nazi government. Begun also developed the Stahltone-Bandmaschine steel tape recorder in 1935 for mobile radio broadcasting. The RRG state radio service used Begun's machines at the 1936 winter Olympic games, but by that time the young Jewish engineer had decided to immigrate to the U.S. (4)

The German engineer Fritz Pfleumer discovered a different method of magnetic recording. While relaxing in a Paris caf- on a business trip in 1927 for the Universelle Company that made cigarette machines, he thought of coating paper tape with iron oxide in the same way that he had been coating cigarette paper with bronze powder lacquer. His German patent for "sounding paper" was granted Jan. 1, 1928, but his tape recorder tore up the paper tape and was only used to demonstrate the potential of tape for editing and reuse. Hermann Bucher, Chairman of the Board of Directors of AEG took a personal interest in this potential and signed a contract with Pfleumer Nov. 28, 1932, to develop a recorder. Theo Volk led the AEG team that worked with Pfleumer and with another team led by chemist Friedrich Matthias of BASF, a subsidiary of the I. G. Farben chemical giant. AEG had expertise in producing high-frequency coils filled with carbonyl iron powder supplied by BASF, and I.G. Farben also produced films and plastics and a variety of coated materials. The partnership created by Bucher and Pfleumer because both were music lovers, would become one of the greatest corporate research and development triumphs of the century. Over the next three years, the teams perfected a tape and recorder that became the standard design for the industry for the next 30 years. Eduard Schuller patented in 1933 the ring-shaped magnetic head that was one of the team's most important inventions. Previous heads were shaped like phonograph needles or chisel and damaged the soft tape. Schuller's ring focused a strong magnetic field on a small area of tape without touching the surface. Matthias developed a two-layer magnetic tape, bonding a top layer of carbonyl iron powder with a base layer of cellulose acetate, similar to the kind of layered safety film made by Agfa for photography. Measuring and testing devices were invented to evaluate the performance of the recorders built by AEG. A tape drive system of capstans and motors and brakes had to be created, and everything had to work with the electronics of amplifiers and speakers. Finally, the Magnetophone K1 debuted at the Berlin Radio Fair in August 1935. (5)

The Magnetophone appeared at a time in the 1930s when other kinds of magnetic recorders were being developed in Britain, the United States, and Japan. Ludwig Blattner had bought the rights to a steel tape device from Kurt Stille in 1929 that became the Blattnerphone. The BBC needed a recorder for its shortwave radio Empire Service that could broadcast the same program at different times throughout the British Empire, and improved the dc motor of the Blattnerphone with a synchronous ac motor and reduced the steel tape width to 3 mm. The BBC would use these improved steel tape recorders from 1932 to 1936. The Marconi Wireless Company also improved the Blattnerphone for sale to radio stations in Canada, Australia, France, Poland, and Egypt. In 1935, the BBC and Marconi and Stille Inventions Ltd. joined to develop an improved Marconi-Stille recorder with a signal-to-noise ration of 45 dB. However, the steel tape was persistent problem. It took two people to mount the 2700-meter reels that weighed 35 kg, and the brittle tape broke so frequently that the Marconi-Stille recorders came with a built-in spot welder. In the United States, Clarence Hickman at Bell Labs developed a steel tape telephone recorder but Bell did not market the machine outside the company. Semi Begun developed the Soundmirror steel tape recorder in early 1939 at the Brush Development Company in Cleveland, Ohio, that would be used by the military. Marvin Camras invented an improved recording head for wire in 1939 at the Armour Research Foundation in Chicago, and added his rediscovery of ac bias in 1940 for the Model 50 commercial wire recorder introduced in 1940. Kenzo Nagai in Japan also rediscovered ac bias in 1938 and patented its application to voice recording. His work would stimulate the Japanese consumer electronics industry after World War II. (6)

The German Magnetophone had advantages over all other magnetic recorders. It was portable (the "K" stood for "Koffer" or portable case in the K1 model of 1935) and was self-contained with its own amplifier and speaker. It was cheaper and more reliable than the steel wire and tape machines. It was financed and manufactured by large and powerful corporations in Germany. The Germany military adopted a field version called the Tonschreiber, or "sound writer," and AEG made a very small spring-driven model C and a model D for war correspondents and a model F dictation machine. The models made for the German Navy were the RE-3 and the R-26. BASF developed a factory to mass-produce the reels of acetate tape, replacing the carbonyl iron coating (light gray in color) with magnetite (black). BASF tested the new tape by recording a concert by Thomas Beecham and the London Philharmonic Orchestra Nov. 19, 1939, at the factory in Ludwigshafen. But the quality of the tape recording that still used dc bias was not good. BASF improved the tape in 1939 with a new formulation of gamma ferric oxide (reddish-brown). The German broadcasting group RRG joined the AEG-BASF partnership and worked to improve its quality. RRG engineer Walter Weber re-discovered ac biasing in April 1940 and the Magnetophone demonstrated to journalists in Berlin June 10, 1941, produced a 60 dB dynamic range and the 50-10,000 kHz frequency response. The model K7 in 1943 had synchronous motors to reduce wow and flutter and could even record in stereo. The tape speed of 30 ips (77 cms) became the standard for future speeds of 15, 7.5, 3.75 and 1.875 ips. Karl Schwarz of the Klangfilm company in Berlin developed a magnetic film stock tape that allowed sound to be recorded on the new color film from Agfa. Although an accidental explosion destroyed the Ludwigshafen tape manufacturing plant in July 1943, the production was taken over by the Agfa plant in Wolfen. A new plant was built in Aschbach neat Ludwigshafen to make the Type L tape with a polyvinyl chloride plastic base that increased sensitivity by 10 dB. (7)

Major John T. Mullin brought the Magnetophone to America at the end of the war. He was an electrical engineer in the Signal Corps assigned to investigate radar interference in Britain. As he listened to hours of music broadcast from Germany each night, he wondered how full orchestras could be playing symphonies at all hours of the night. The quality was equal to live radio, and was better than shellac records. On a trip to Radio Frankfurt he discovered the secret: Magnetophones with ac biasing. He studied the circuitry of these machines, and sent 2 old machines with dc biasing home to San Francisco with 50 reels of BASF Type L tape. He modified the electronics of the old machines to add dc biasing and demonstrated them May 16, 1946, to the Institute of Radio Engineers in San Francisco. Harold Lindsay heard this demonstration and told Mullin about the Ampex Corporation that had been founded by Alexander Matthew Poniatoff in 1944 (the name came from his initials plus "ex" to avoid using the same name AMP already taken by the Aircraft Marine Products company). Ampex Electrical and Manufacturing Company built high quality motors and generators that used Alnico 5 magnets from the GE, but with the war ended Poniatoff was looking for a new product. Mullin provided Ampex with some information about his Magnetophone but was also supplying information to Col. Richard Ranger in New Jersey who was developing his own tape recorder. Ampex used the FIAT reports of the U.S. Government Intelligence Agency Reports on German industries to gain more information to develop its own tape recorder design. (8)

Bing Crosby opened the floodgates for magnetic tape recording in the broadcast industry. Despite the network prohibition of recordings, during the war years some radio stations had started using Brush and Armour wire recorders for broadcasting news events and for west coast delayed time. The new ABC network allowed Bing Crosby to record his "Philco Radio Time" show in the fall of 1946 on transcription discs but these were difficult to edit. Crosby's technical producer Murdo McKenzie learned about Mullin's Magnetophone, now called the Magnetrack for a motion picture film recording business he started with W. A. Palmer in Hollywood. In August 1947 McKenzie arranged three different recordings of Crosby's first Philco show of the 1947-48 season: by Mullin, Ranger, and transcription disc. Mullin's tape recording was superior and won the contract to record and edit Crosby's radio shows. Ampex was finishing its prototype of the Model 200 tape recorder and Mullin used the first two models as soon as they were built. Crosby invested $50,000 in the Ampex company to expand production, and Bing Crosby Enterprises became its West coast distributor. The radio networks and the leading recording studios adopted the recorders. Ampex later boasted that the tape recorder and the LP "gave birth to the high fidelity era." (9)

Ampex was not alone. During World War II, Semi Begun at the Brush company developed a ring-type recording head under contract with the Office of Scientific Research and Development. This ring worked best with coated tape and with Gerard Foley of the Batelle Memorial Institute developed paper and acetate tapes coated with alnico and magnetite powders. Brush approached a number of companies, including the Minnesota Mining and Manufacturing company, to manufacture the tape. In 1944, Ralph Oace at 3M solved the problem of coating a paper base with the magnetite powder, but the war ended the funding for the project. The Shellmar company manufactured the paper magnetite tape in 1946 for the Brush Soundmirror tape recorder and also a 5-inch magnetic disk for the Brush Mail-A-Voice disk recorder that sold for only $40. The experiments of Oace and the FIAT reports of the German BASF tapes caused the 3M company to create a magnetic tape laboratory in 1946. This lab discovered that needle-shaped acicular particles of gamma ferric oxide produced better coercivity (350 oersteds) than the cube-shaped particles of magnetite used by Brush (150 oersteds). 3M introduced the Type 100 paper tape (black oxide) in 1947, and the popular Type 111 acetate tape (red oxide) in 1948 that Bing Crosby used to record his Philco show with the new Ampex 200 tape recorders. By 1948 the American tape recorder industry was firmly established. The Magnecord company introduced the PT-6 professional recorder for $750, far less than the Ampex models, and a stereo model in 1949. (10)

The motion picture industry was quick to adopt the tape recorder for its ability to edit sounds during production, and for the improved quality of sound during exhibition. This is Cinerama premiered Sept. 30, 1952, at the Broadway Theater in New York and would play for 122 weeks. This 3-projector system designed by Fred Waller used a wide curved screen and a separate 7-track magnetic soundtrack designed by Hazard E. Reeves for specially equipped theaters. The Robe premiered Sept. 16, 1953, at the Roxy in New York in Cinemascope by Twentieth Century Fox with 4-track magnetic soundtrack on the edge of each 35mm cellulose tri-acetate filmstrip. Oklahoma! premiered Oct. 10, 1955, at the Rivoli Theater in New York in 65mm Todd-AO with a separate 6-track magnetic soundtrack system designed by Westrex and Ampex, running at 5400 inches per second (ips) in synch with the film projector running at 8415 ips (30 fps). Michael Todd joined with Joe Schenck of Fox and George Skouras of United Artists Theatre Circuit to form the Magna Theatre Corporation for production and distribution of Todd-AO films. (11)

The emerging computer industry saw magnetic recording as a solution to the problems of data storage and speed. In 1937, Victor Atanasoff considered a variation of Poulsen's magnetic drum as a possible memory device for his early ABC electronic computer. However, he could not afford the vacuum tubes necessary to amplify the magnetic pulses, and decided to use non-magnetic capacitors on the drum. In 1947, William C. Morris led a group of engineers at Engineering Research Associates (ERA) in Minneapolis that had worked on Project Goldberg for the Navy to develop a computer that could solve cryptographic problems. They built the first magnetic drum out of recording tape from a captured German Magnetophone recorder and heads from a Brush wire recorder. The strips of tape would not stick to the aluminum drum, so they spray-painted an iron oxide emulsion obtained from 3M in Minneapolis directly onto the surface of the drum. John Coombs reported their success at the Chicago National Electronics Conference in November 1947. The drum was 5 inches in diameter and revolved at 3000 rpm, recording at a density of 230 bits per inch with a rigid head mounted only .001 inch from the surface of the drum. Howard Aiken at Harvard was also experimenting with a magnetic drum on the Mark II computer in 1947, and he would make the drum the key feature of his improved Mark III computer in 1948. Harry Huskey would use a magnetic drum in this design of the Standards Eastern Automatic Computer for the National Bureau of Standards in 1948. Arnold D. Booth in Britain built a magnetic drum for the Automatic Relay Computer in 1948 and would install a drum in the Manchester "baby" computer in 1949. The ERA would build the Atlas computer in 1948 with a magnetic drum 8.5 inches in diameter with 200 read/write heads and a capacity of 16,384 words of 24-bit length. The ERA would patent its drum design in 1948, including the so-called "sprocket track" that was a control track to map the addresses of data in the storage tracks. The access speed and large capacity of magnetic drums exceeded all other forms of computer memory in use during the decade after World War II, such as the CRT and the mercury delay line. It would remain the preferred computer memory until the faster magnetic core devices became available in the late 1950s. (12)

The magnetic drum was fast but did not have the large capacity needed for data storage. John W. Mauchly and J. Presper Eckert began work in 1943 on ENIAC at the University of Pennsylvania for the U.S. Army. It was not finished during the war but in 1946 they started the Electronic Control Co. and received grant from National Bureau of Standards to build a ENIAC-type computer with magnetic tape input/output, renamed UNIVAC in 1947 but the project ran out of money. The two scientists formed Eckert-Mauchly Computer Corporation (EMCC) in Dec. 1947 and developed by 1949 the BINAC stored-program computer for Northrop Aircraft, with mercury delay line memory and a primitive magnetic tape drive. Remington Rand bought EMCC in Feb. 1950 and provided funds to finish UNIVAC March 30, 1951. It announced on June 14, 1951, the sale of UNIVAC I to the Census Bureau. It was the first commercial computer to feature a magnetic tape storage system that consisted of eight UNISERVO tape drives standing separate from the CPU and control console on the other side of a garage-size room. Each tape drive was six feet high and three feet wide, used 1/2-inch metal tape of nickel-plated bronze 1200 feet long, recorded data on eight channels at 100 inches per second with a transfer rate of 7,200 characters per second. The complete UNIVAC system weighed 29,000 pounds, included 5200 vacuum tubes, and an offline typewriter-printer UNIPRINTER with an attached metal tape drive. Later, a punched card-to-tape machine was added to read IBM 80-column and Remington Rand 90-column cards. The UNIVAC I was used in November 1952 to calculate the presidential election returns and successfully predict the winner, although it was not trusted by the TV networks who refused to use the prediction. Magnetic tape systems became the standard data storage system in the 1950s. The SAGE aircraft-warning system was the largest vacuum tube computer system ever built. It began in 1954 at MIT's Lincoln Lab with funding from the Air Force. The first of 23 Direction Centers went online in Nov. 1956, and the last in 1962. Each Center had two 55,000-tube computers known as "Clyde" that weighed 275 tons and had magnetic core memory, magnetic drum and magnetic tape storage, graphics display, and were connected by one of the first computer networks. (13)

At IBM in 1952, Arthur J. Critchlow began the Source Recording project at the new IBM research lab in San Jose, California, under the direction of Reynold B. Johnson. The purpose was to find a better method than punched cards or drums or tape to store and access information. They read an article by Jacob Rabinow at the National Bureau of Standards in the August 1952 issue of Electrical Engineering about "The Notched-Disk Memory" that stored magnetic pulses on thin metal disks mounted vertically in a doughnut-shaped ring. Each disk had a notch to align magnetic read/write heads. Critchlow adopted this magnetic disk idea in February 1953 and Johnson began work at San Jose on a 50-disk system with the capacity of 50,000 punched cards, or 4 million characters. In April 1953, William A. Goddard headed a team of 4 engineers to develop the disk device. In May, he adopted the "air head" method of maintaining a uniform head-surface gap of .002 inch using a forced air cushion. In June a successful test was completed with the airhead reading a writing digital data on the surface of a 16-inch aluminum disk sprayed with iron oxide paint. By October, spray paint was replaced by spin coating, and a servo-controlled cable-and-pulley carriage was used to successfully locate random tracks on the spinning disk. In February 1954, data was being transferred to and from a card reader. During 1954 a Model II was designed and built with a 50-disk array mounted on a vertical shaft. This model was given its first public demonstration in May 1955 as the Random Access Memory Accounting Machine, or RAMAC. An improved Model II was demonstrated at the February 1956 Western Joint Computer Conference. Each disk was 24 inches in diameter and 0.1 inch thick and separated from other disks by 0.3-inch spacers. The disks revolved at 1200 rpm and were accessed by a single read/write head that moved up and down the stack of platters Each disk had 100 circular tracks with a density of 500 characters per track, recorded by IBM's NRZI variable density method of 100 bits per inch on the inner track and 55 bits per inch on the outer track. This was the equivalent of storing 5 MB on a magnetic drum 13 inches diameter and 42 feet long. The disk array became the IBM 350 Disk Storage, and deliveries to customers began in June 1956 for a monthly lease of $750. The IBM 1301 Disk Storage was announced June 2, 1961. Each module had 25 disks and could store 28 MB. Up to 10 modules could be added to a computer for a maximum of 280 MB. Each disk had 50 tracks per inch with 520 bits per inch density, rotating at 1800 rpm. This was first used in the SABRE airline reservation system in 1961 that used 6 magnetic drums and 16 modules of the 1301 Disk Storage unit. The drums only had capacity for 1.1 MB each, but were 20 times faster in access time. In September 1963, the 1302 Disk Storage increased capacity 4 times by doubling the tracks per inch and the bits per track. The 1316 Disk Pack announced October 11, 1962, (at first called the 1311 Disk Storage Drive) was a removable pack of 6 disks, with a capacity of 2 MB, and popular with smaller computers and a versatile storage medium. (14)

The computer and the transistor in the 1950s joined with the automobile and the teenager to create a new generation of stereo "Hi-Fi" components. Magnetic tape and FM radio made possible a new quality of sound. The tape recorder industry quickly expanded in Europe and Asia after the war. In Britain, EMI used the German design to produce the BTR1 for its Abbey Road studio in November 1947. The Grundig Company in Germany was started by radio dealer Max Grundig after World War II to produce radio repair instruments. It expanded into radio set production, making the Heinzelmann in 1946 and the Grundig Boy in 1949 that was one of the first portable cabinet radios. Grundig took over the Lumophon factory in Nuremberg and in 1951 began production of its first tape recorder, the Reporter 300. Willi Studer in Zurich produced his first recorder, the Dynavox, in 1949 and the Studer 27 in 1951 and the Revox A77 in 1967. Stefan Kudelski, a physics student in Switzerland, built the Nagra I portable tape recorder with wind-up motor in 1951 used by the Everest explorer Raymond Lambert and by the deep-sea bathyscaph Trieste. In Japan, Sony ( then called Totsuko) in 1950 sold its first G-type tape recorder in Tokyo at a price of $400 but it weighed over 100 lbs. Masaru Ibuka and Akio Morita licensed transistor technology from Western Electric in 1953, and began a consumer electronics revolution with transistor radios, TVs (the TV8-301 of 1960 was nicknamed "Kennedy's dog" because JFK kept a set near him), and the first all-transistor tape recorder in 1961. (15)

The videotape recorder would become one of Sony's greatest successes, but it began as another example of the influence of Bing Crosby. John Mullin at Bing Crosby Enterprises demonstrated an experimental 12-head VTR at 100 ips in 1951. The Ampex team led by Charles Ginsburg began work on VTR in October 1951. Ray Dolby, 19, dropped out of school to join the project and helped the team demonstrate the first system Nov. 19, 1952, but with a poor picture. A second system in March 1953 used 4 heads rather than 3 but problems continued with "venetian blinds" effect due to discontinuous recording from one head to the next. By 1954, the Ampex team included with Charles E. Anderson, Shelby Henderson, Fred Pfost, and Alex Maxey. By Feb. 1955 Anderson designed an FM circuit; Ray Dolby rejoined the team after his stint in the Army and designed a multivibrator modulator by Feb. 25; Maxey discovered how to vary tape tension and Pfost developed a new sandwich-type magnetic head. The improved model was shown in Feb. 1956 to Bill Lodge of CBS and other TV people in preparation for the first public demonstration in April. The Mark IV went on public display April 16, 1956, at the Chicago convention of the National Association of Radio and Television Broadcasters, the same day that Ray Dolby demonstrated the older Mark III in Redwood City. The Mark IV, later renamed the VRX-1000, used 2-inch wide 3M tape at 15 ips over rotating head assembly recording at a slant on tape surface with AM sound. During the next 4 weeks, Ampex took orders worth $4.5 million, and took out a trademark on the name "videotape" for its recorder. CBS used a new Ampex VTR for the delayed broadcast of "Douglas Edwards and the News" Nov. 30, 1956. Color videotape was used to record the Nixon-Khrushchev Kitchen Debate in Moscow in 1959. (16)

Color was not the only new development in 1959. Toshiba in September demonstrated prototype helical scan model VTR-1, with 2-inch tape running at 15 ips over just one head. After the demonstration, Sony began to develop the helical scan VTR. Sony persuaded Ampex to share its VTR patents and Sony shared transistorized circuitry with Ampex. In1961, JVC (founded as the American-owned Victor Co. of Japan in 1946, but owned by Matsushita since 1953) demonstrated helical scan color VTR with 2 heads to compete with Sony's PV100 that was adopted by American Airlines in 1964 for in-flight movies. Helical scan technology held great promise for its potential to reduce the size of tape machines and permit slow motion and stop action effects, but not for another decade. The first "instant replay" on commercial television in March1967 at the ABC "World Series of Skiing" in Vail, Colorado, was not by videotape but with the Ampex HS-100 color video magnetic disk recorder. Sony tried to develop a consumer VTR in the 1960s, but the open-reel machines were too large and complicated and expensive. (17)

The answer to these problems came from Holland. In 1965, the Philips company introduced the compact cassette for consumer audio recording and playback on small portable machines such as the Norelco Carry-Corder 150. Philips intended the cassette to be used for business dictation, and had no idea that it would appeal more to consumers who wanted a simple method to record music. The cassette used 1/8-in. tape with 4-tracks running at 1-7/8 ips, allowing 30 or 45 minutes of stereo music per side, and most importantly, was only 1/4 the size of other cassette systems. Earl "Madman" Muntz in California had become successful putting the 4-track Fidelipac in his cars, and William Lear modified the Muntz player with new small record heads from Nortronic to create the 8-track player in 1964, adopted by RCA and Ford. These players were fine for cars and Learjets, but too large to carry in your pocket. The Philips compact cassette would soon dominate the world market and push the 8-track players into the dustbin of history. (18)

The cassette format became the basis of the videotape revolution in the 1970's. Sony introduced the 3/4-inch U-matic VCR in the U.S. in 1971, and for the first time, allowed other manufacturers to sell machines that could play the cassette, and thus succeeded in establishing a world standard for the 3/4-inch videocassette. In 1975 Sony introduced in the U.S. the Betamax consumer VCR console for $2295 with one-hour 1/2-inch tape cassettes for $15.95. Sony sought to create a standardized format, as it had done with the U-matic, by getting other companies to produce machines that would play the Beta cassettes, but refused to license the cassettes themselves. The next year JVC introduced the VHS format and a VCR for only $885 and licensed the technology to other companies. Sony would lose the "Betamax War" with VHS, but it would triumph with the Walkman portable audio cassette player in 1979. The TPS-L2 inaugurated a new era of personal music listening. The Sony family of portable personal music players would grow to include over 500 models, from the original pocket-sized 14-oz Walkman to the D-88 Pocket DiscMan of 1988 to the DAT Walkman TCD-D3 of 1991 to the MiniDisc of 1992 to the digital Discman of 1999. According to Sony, in the 20-year history of the Walkman devices, 100 million units were sold in the U.S. creating a $1 billion industry. (19)

The transformation of the credit card created a multibillion-dollar industry. IBM had perfected in the 1960s a method of adhering a magnetic stripe to the surface of a plastic credit card. This stripe could have multiple tracks and allow read and write operations from special machines capable of decoding binary data. American Airlines and American Express first used striped cards for ticketing at O'Hare Airport in Chicago. The first of three tracks on early credit cards was used by the airline industry. The second track contained identifying information such as account numbers and names. The third track was read-write and could hold the balance of an account. The American Banking Association approved use of the magnetic stripe in 1971 but most banks resisted its use. In 1972, Dee W. Hock, president of National BankAmericard Inc. (NBI, later to be called Visa), adopted the magnetic stripe for its new Uni-Card division in competition with the cards of the nation's largest banks, including Bank of America and Citibank. Eventually, the banks followed his lead and made the magnetic stripe common on all credit cards. (20)

One of the most significant developments of the 1970s was the floppy disk. The engineers at IBM who had developed RAMAC and the early disk drives understood their significance. In late 1967, a group known as "Dirty Dozen" left the IBM research lab in San Jose to found Information Storage Systems (ISS) that sold disk drives through Telex. They were followed during next three years by over 200 other engineers who would leave IBM for the new disk drive companies like Memorex and Shugart Associates. After the departure of the Dirty Dozen, IBM assigned David I. Noble the job of designing a cheap and simple device to load operating code into large computers. Called the Initial Control Program Load, it was supposed to cost only $5 and have a capacity of 256 KB. During 1968 Noble experimented with tape cartridges, RCA 45-rpm records, dictating belts, a magnetic disk with grooves developed by Telefunken, but finally created his own solution -- the floppy disk. Called the "Minnow," it was a plastic disk 8 inches in diameter, 1.5 mm thick, coated on one side with iron oxide, attached to a foam pad and designed to rotate on a turntable driven by an idler wheel. A read-only magnetic head was moved over the disk by solenoids and read data from tracks prerecorded on the disk at a density of 1100 bits per inch. The disk was "hard-sectored" with 8 holes around the center to mark the beginning of data sectors. At first, its capacity was only 81.6 KB, but by Feb. 1969 he had doubled the thickness of the plastic base to 3 mm and coated both sides to add more capacity. In June 1969, the Minnow was added to the IBM System 370 and soon began to be used by other divisions in IBM. In 1970, the name was changed to Igar and Noble had a staff of 25 engineers to help him make improvements. By 1971, Igar became the 33FD disk drive and the 8-inch floppy disk became the Type 1 diskette. The speed was 360 rpm, with head access time of 50 milliseconds. The 8 hard sector holes were replaced by a single index hole for "soft sectors" or "IBM sectoring" across 77 tracks. In 1976 the 43FD disk drive was sold with dual heads to read and write to both sides of the diskette. A new model 53FD was added in 1976 that used modified frequency modulation to record double-density on both sides, resulting in a capacity of 1200 KB. (21)

The floppy disk emerged from IBM at the same time the microprocessor emerged from Intel. When the first Altair and Imsai microcomputers came on the market in 1974 using the 8080 processor, there were no peripherals available to store data or even display words on a CRT screen. The only input/output device was a Teletype. There wasn't even an operating system for these new computers. In 1975, Alan Shugart produced an 8-inch floppy disk to hold 800k that offered for the first time a low-cost drive for the emerging personal computer market. In 1976, Jim Adkisson, a Shugart engineer, sat down for lunch with a customer who complained that the 8-inch drive was too big for the personal computer. When Adkisson asked what the size should be, the customer pointed to a napkin on the table and said, "About that size." Adkisson returned to the Shugart lab with the napkin and designed the 5.25-inch floppy drive, introduced in 1976 as the model SA400 with a capacity of 110 KB. The model became one of Shugart's best sellers, with shipments the rose to 4000 drives per day. The company turned to Matsushita in Japan to help make the drives, starting that company on its rise to becoming the largest floppy drive manufacturer in the world. Sony developed a 3.5-inch floppy drive by 1980 and began a two-year effort to make it the U.S. floppy disk standard. Sony declared that its new drive was smaller, faster, better protected, and could fit in a shirt pocket. A group of U. S. disk manufacturers opposed the new standard. The group was led by Shugart Associates and Control Data, and included Verbatim, Micro Peripherals, Dysan and Tabor. They sought to keep the standard 8-inch and 5.25-inch disks made by U.S. companies since IBM introduced the floppy disk in 1971. However, no American company had a product equal to the Japanese diskette. Sales of the 3.5-inch floppy began to surpass the 5.25-inch version by 1989, and Japanese companies would drive most U.S. disk producers out of the market. (22)

The Digital revolution of the 1980s continued the use of the cassette and disk and magnetic tape. In1986 Sony/Philips introduced Digital Audio Tape, or DAT, as a result of efforts of the 81-member firm R-DAT consortium to develop a recordable version of the optical compact disc. Because of copyright problems, electronics firms delayed development of consumer products and DAT remained a high-priced professional medium. In 1991 the Alesis Corporation of Los Angeles introduced its new ADAT machine that recorded 8 tracks of digital audio to a standard S-VHS videocassette using the same helical scan technology that created the videocassette boom in the 1970s. With a list price of $3995, and cassettes at $15, the ADAT made multitrack digital recording affordable for the small studio, with the ability to connect together up to 16 ADATs for a total of 128 synchronized tracks. 20,000 were sold in its first year from October 1992 to November 1993 and 80,000 sold by 1998. The Electronic Musician declared in Oct. 1992 that "ADAT is more than a technological innovation; it's a social force." In 1992 Sony began sales of the MiniDisc that had been announced May 30, 1991. The MD was a recordable magneto-optical disc encased in a plastic cartridge with the same 74-minute capacity as the CD but at half the size and with greater compression. The MD was intended to replace the CD and the compact cassette. Sales of cassette tapes began to decline in1989, and Sony felt that the compact cassette system was nearing the end. In1993 the Tascam division of Teac introduced in February the DA-88 digital 8-track recorder for $4,499, the first modular digital multitrack (MDM) recorder to use the Hi-8 videotape. In1997 sales began of the Digital Video cassettes following the DV and miniDV standard introduced by Panasonic & Sony. In 1999 Panasonic announced Digital-VHS (DVHS), the first VCR capable of recording all 18 Digital TV format including HDTV. Just as computers continued to use magnetic hard disks to store data, audio recording continued to use magnetic tape and cassettes for the new era of digital sound. (23)

NOTES:

1. On Morse and the telegraph see Lewis Coe (1993; on Bell and the telephone see Robert Bruce (1990). On Oberlin Smith see Mark Clark "The Magnetic Recording Industry" (1992) and his Chapter 2 of Magnetic Recording: the First 100 Years, edited by Daniel et. al. (1999).

2. On Poulsen see Begun's Chapter 1 (1949), and Mark Clark "The Magnetic Recording Industry" (1992) and his Chapter 3 of Magnetic Recording: the First 100 Years (1999).

3. On Sayville and the Navy, see Morton (1995) pp. 89-90.

4. On Stille and Begun see Begun's Chapter 1 (1949) and Mark Clark's Chapter 4 of Magnetic Recording: the First 100 Years (1999).

5. On Pfleumer see Friedrich Engel's Chapter 5 of Magnetic Recording: the First 100 Years (1999).

6. On steel tape in the 1930s, see Begun's Chapter 1 (1949), Morton Chapter 3 (1995).

7. On the German Magnetophone see Friedrich Engel's Chapter 5 of Magnetic Recording: the First 100 Years (1999) that used primary documents of BASF (now EMTEC).

8. On Mullin see Nmungwun's Chapter 4 (1989) that used primary documents of Ampex and interviews with Mullin; see also the Mullin videotape from the Audio Engineering Society.

9. On Crosby see Nmungwun's Chapter 4 (1989); the Mullin videotape (1989); Schoenherr "Der Bingle Technology" (2002); Ampex quote from Perry (1967).

10. On Begun see Begun's Chapter 1 (1949) ; Beverley Gooch's Chapter 6 of Magnetic Recording: the First 100 Years (1999); letter from Ralph J. Oace to Bert S. Groves, Jan. 31, 1964.

11. On motion picture sound see Belton (1992).

12. On the magnetic drum see Schoenherr "The Magnetic Drum" (2003).

13. On UNIVAC see Gray (2001); on SAGE see Spicer (2000) and Schoenherr "The SAGE Air Defense" (2000).

14. On RAMAC see Johnson (1989); Schoenherr "The Floppy Disk" (2003).

15. On tape recorders see Angus (1984); Grundig history (2002); Nagra history (2002); Sony history (2002); Studer history (2002).

16. On the VTR see Nmungwun's Chapter 6 (1989); Ginsburg (1957).

17. On helical scan, see Nmungwun's Chapter 7 (1989); Schoenherr "Television Instant Replay" (2002).

18. On the cassette see Morton's Chapter 8 "The Eight Track Tape Cartridge" in his "History of Magnetic Recording" (1995).

19. On the Walkman see David Frith (1999).

20. On Dee Hock and the credit card, see Mandell (1990).

21. On the floppy disk see Schoenherr "The Floppy Disk" (2003) .

22. On Shugart see Schoenherr "The Floppy Disk" (2003).

23. On the digital revolution, see Schoenherr "The Digital Revolution" (2001).

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"History of Magnetic Recording" presented at IEEE Magnetics Society Seminar, UCSD, Nov. 5, 2002.


 
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AES - Audio Engineering Society