The Digital Revolution

PCM chart from
Electronic World 1970/10

1937 - Alec H. Reeves invented pulse-code modulation (PCM) when he worked for the International Telephone and Telegraph Co. in France. He was granted a French patent in 1938, a British patent in 1939, and U. S. patent 2,272,070 in 1942. Bell Labs used PCM in the secret SIGSALY telephone encryption system 1943-1946. The first commercial use of PCM was in telephone transmission in 1962 after the development of integrated circuits made such use practical; the analog voice sound wave within the telephone bandwith of 4000 Hz was sampled at 8000 pulses per second and each pulse was encoded with a digital value; the digital values were multiplexed for transmission as a linear series of identical pulses and each pulse coded with a sampled amplitude at a particular point in time on the voice sound wave.

1939 - John V. Atanasoff and graduate student, Clifford Berry, build the first electronic computer with a drum storage device that used capacitors on the surface of the drum to temporarily store data used by separate logic circuits to process the data. They programmed the computer using the binary algebra of 19th century mathematician George Boole (1815-1864) who demonstrated that simple equations could be written as either true or false. The Atanasoff-Berry-Computer (ABC) had 2 drums with capacitors to store 30 numbers on each drum, each number stored in 50 bits. In 1942, Perry Crawford, independently of Atanasoff, described a magnetic drum that could be used to store electronic digital information in his 1942 MIT master's thesis, "Automatic Control by Arithmetic Operations." The Evolution of the Computer and the ability to record data to magnetic drum and disk and tape would play a key role in the development of digital audio.

1943 - The first telephone "hot-line" used vacuum tube frequency inversion to code transmissions between Winston Churchill and Franklin Roosevelt in World War II. The electronic equipment codenamed SIGSALY came from the research of Bell Labs and was one of the earliest uses of PCM. The installation in London was so large that it required the basement room of the Selfridges Department store.

1946 - Engineering Research Associates (ERA) in August used parts of captured German Magnetophones to build magnetic drums and disks under Project Goldberg for the Navy (Task 1-H to decipher encryptions). The magnetic drum designed by ERA would be used in the computers built in the U.S. over the next years by Harvard, IBM, Remington Rand, National Security Administration, National Bureau of Standards.

1947 - The germanium transistor was first demonstrated privately at Bell Labs Dec. 23, 1947, by William Shockley and his team. However, production problems delayed its practical use. Until it was perfected, the invention was kept secret for 7 months and no patents were filed until 1948; the first public announcement was June 30, 1948. Raytheon was first to mass-produce transistors in 1952 and the first to produce a commercial product with transistors, the hearing aid. Shockley in 1955 moved to a Quonset hut at 391 San Antonio Road in Mountain View near his Palo Alto home and became one of the founders of "Silicon Valley" in California, a center of digital research and development. In 1957, a group of engineers known as the "Traitorous Eight" left Shockley and founded Fairchild Semiconductor to manufacture transistors. It was at Fairchild that Robert Noyce would patent the process for making IC chips. In turn, engineers would depart to form new companies, the "Fairchildren" who founded Advanced Micro Devices Inc., LSI Logic Corp., Teledyne, Rheem, National Semiconductor, Intel.

1948 - The "Baby" computer at the University of Manchester ran the first stored program June 21, using old radar CRT tubes to store 2048 bits per tube (see 50th Anniversary of the Mark I). By April 1949 a magnetic drum designed by Andrew Donald Booth was added for secondary memory.

drum memory of the Atanasoff-Berry Computer 1939, from Smithsonian NMAH
1951 - The UNIVAC was the first computer to feature a magnetic tape storage system.

1952 - Kurt Vonnegut published the novel Player Piano set in a future world where workers have lost all control to managers and computer-controlled machines. The main character loses his job, goes to a bar, starts a player piano, and the character realizes that there is no human pianist, only his spirit captured in the holes of the piano roll.

1953 - Jay W. Forrester at MIT installed the first magnetic core memory in the Whirlwind computer; the small magnetic rings were developed after 1949 and tested in a 16x16 array in May 1952 (Munro Haynes independently tested core memories the same month in a 80x12 array at IBM); Whirlwind was developed first as a flight trainer for the Navy starting in 1943 but changed to an air defense system after the Russian A-bomb of 1949 and was installed in MEWS Apr. 1951, and IBM joined the project in 1952 and shipped the XD-1 Jan. 1955 to replace the Whirlwind. IBM developed the computers for the SAGE air defense system 1956-84 that used magnetic core memory and magnetic drum storage. The core memory would be used until replaced by integrated circuits in the 1970s. SAGE had great effect on pushing IBM ahead of Remington Rand and making it a world leader in computer R&D .

1954 - IBM built the model 604 computer in October, its first with transistors, that became the basis of the model 608 that shipped Dec. 1957, the first solid-state computer for the commercial market. Tom Watson, Jr., pushed the development of transistors in all new IBM computers.
Schawlow adjusts a ruby optical maser at Bell Labs, while C. G. B. Garrett prepares to photograph the maser flash in 1960 experiment, from AT&T Archives
IBM signed agreement with TI in Dec. 1957 for TI to supply IBM with semiconductors.

1955 - In May, IBM announced the first commercial magnetic disk, called RAMAC ("random access method of accounting and control"), that could could store 5 million bits (in 7-character words) on 50 aluminum disks, each two feet in diameter, coated on both sides with magnetic iron oxide (similar to the paint primer used on the Golden Gate Bridge), and using a single read/write head. This huge disk assembly that weighed a ton was sold in September 1956 as part of the IBM 305 system.

1958 - Arthur L. Schawlow published his paper "Infrared and Optical Masers" in the Physical Review of Dec. 1958; this was the key paper that started laser development; the word "laser" not yet coined, rather the word maser was used to refer to semiconductor light amplification and modulation; he worked at Bell Labs with Charles H. Townes of Columbia after Dec. 1957.

1959 - General Electric developed Magnetic Ink Character Recognition for the Bank of America in California to automate check processing.

1959 - Jack Kilby of Texas Instruments in Feb. patented the first integrated circuit; Kilby had made his first germanium IC in Oct. 1958; Robert Noyce at Fairchild used the planar process to make connections of components within a silicon IC in early 1959;
Integrated Circuit in
GTE ad, 1974
1929 RCA Theremin
from Radiola Guy
1963 Mellotron from
Brief History of Sampling
1979 Fairlight CMI from 120 Years of Electronic Music
the first commercial IC chips made by Fairchild began to be sold in quantity during 1961. Noyce would later found Intel in 1968 with Gordon Moore and Andrew Grove; the first commercial product using IC was the hearing aid in Dec. 1963; General Instrument made LSI chip (100+ components) for Hammond organs 1968.

1961 - The IBM 7030 computer in April 1961 pioneered the 8-bit character word length (a "byte") that grew out of the Air Force contract of Oct. 1958 following Sputnik to develop transistor computers for the Ballistic Missile Early Warning System (BMEWS).

1962 - Tom Stockham at MIT began creating digital audio tape recordings using a large TX-0 computer and a A/D-D/A converter from Bernie Gordon at EPSCO. In 1963 he helped Amar Bose design the corner 2201 loudspeaker. In 1968 he left MIT for the University of Utah, and in 1975 founded Soundstream with Malcolm Low (the L in KLH) and developed a 16-bit digital audio recorder.

1963 - The Mellotron electronic music sampler recorded musical notes on loops of tape for each key on a keyboard. Unlike the 1920 Theremin that only produced oscillations, or the 1935 Hammond electronic organ, the Mellotron could create realistic sounds of different instruments such as a clarinet or violin. It was used by the Beatles and Pink Floyd, and by Led Zeppelin to create the flute sound at start of the 1971 recording of Stairway to Heaven. Music samplers would not be able to record digitally until Peter Vogel and Kim Ryrie in 1979 developed the Fairlight Computer Musical Instrument (CMI) that used 500k floppy disks.

1968 - Wendy Carlos recorded the electronic music album Switched-On Bach for CBS using a Moog synthesizer. Robert A. Moog had been building and selling transistorized Theremins when he met the composer Herbert Deutsch in 1963 and collaborated to create an electronic synthesizer using patch cables by August 1964. Wendy Carlos was an engineer for Gotham Recording studio and she added fixed filter banks and other improvements to the Moog/Deutsch machine to make her Bach recordings.

1969 - MIT Professor Dr. Francis Lee and engineer Chuck Bagnaschi created American Data Sciences (became Lexicon in 1971) to develop digital audio devices based on Lee's digital delay unit for medical heart monitoring. Barry Blesser developed a 100ms digital audio delay line, and with the help of Steven Temmer at Gotham Audio, sold digital reverberation and effects processors to recording studios, and developing the OPUS digital audio workstation in 1988.

1971 - IBM introduced the first 8-inch flexible plastic "memory disk" that had been developed by Al Shugart to store program code for the IBM 3330 Merlin disk pack. Its initial capacity on one side was 100 KB. The "floppy disk"with its protective jacket quickly was adopted by many manufacturers as a convenient method of transferring programs and data. In 1974, Gary Kildall designed his popular CP/M operating system to use floppy disk storage rather than the punched cards used by most large computers.

1971 - Intel produces large scale integrated (LSI) circuits that are used in the first digital audio device, the digital delay line, and would be used in digital audio processors of Sony, Mitsubishi, Hitachi, JVC, and would be used in the Philips compact disc.

1971 - Intel announced Nov. 15 the 4004 microprocessor, with a word length of 4 binary digits (bits) that was OK for calculators but not for alphabets (required min. 6-bit).

1972 - Philips demonstrated its optical videodisc system in Sept., using laser pickup on 12-in. glass disc; improved model shown at Berlin Radio & TV show 1973.

1972 - Nippon Columbia Co. developed a PCM recorder to master soundtracks, stored on videotape, with dynamic range of 87 db.

1973 - IBM developed the first sealed hard disk drive with two 30-MB disk platters. It was nicknamed the "Winchester" drive because project manager Ken Haughten owned a 30-30 rifle.

1975 - Sydney Alonso and Jon Appleton and Cameron Jones developed the Synclavier digital synthesizer at Dartmouth College, New Hampshire, and formed the New England Digital Corporation the next year (later became Demas) to sell the machine to the professional recording industry.

1976 - The first 16-bit digital recording in the US was made at the Santa Fe Opera on a handmade Soundstream digital tape recorder developed by Dr. Thomas G. Stockham.
Wozniak and Jobs introduced Apple II in 1977, from History of Apple

1976 - Al Shugart developed the 5.25-inch floppy disk drive for the desktop computers sold by Wang Laboratories. The initial single-side single-density disk capacity was 100 KB.

1976 - Steve Wozniak demonstrated the Apple I personal computer in April at the Hombrew Computer Club in Palo Alto, and the next year with Steve Jobs began to sell the Apple II with plastic case, a built-in speaker to reproduce sounds, the ability to display color, and in 1978 added a floppy disk drive.

1977 - Nintendo in Japan began to make computer games that stored the data on chips inside a game cartridge that sold for around $40 but only cost a few dollars to manufacture. It introduced its most popular game "Donkey Kong" in 1981, Super Mario Bros in 1985. By 1989, it was earning a profit of $1 billion per year with only 850 employees, controlled 85% of the home video game market, would sell 50 million game machines by 1992 and 1 billion cartridges by 1995.

1977 - AT&T began fiber optic transmission of telephone signals in the Chicago Loop, downtown Chicago. The first intercity fiber optic route began in 1983 between New York and Washington. The first transatlantic fiber optic telephone cable, called TAT-8, began Dec. 8, 1988.

1978 - RCA introduced the Selectavision videodisc that had taken 15 years and $200 million to develop since the 1964 decision by Robert Sarnoff, son of David, to develop a low-cost consumer recorder; Selectavision used a 12-inch vinyl disc at 450 rpm that held 200 times more data than LP, read by electrode on a stylus that sensed change in capacitance; played 2 hours with signal-to-noise of 46db; CED (capacitance electronic discs) sold for $15 and the SFT-100 player sold for $500, cheaper than the Betamax ($900 in 1980) or Philips Laservision or Pioneer Laserdisc (both $750 with discs priced at $40 in 1980).

1978 - PCM consumer audio recording began in June with the introduction of the PCM-1 14-bit Betamax accessory for recording and playback of digital audio with an 80db dynamic range.

Sony's first CD player
1980 - The Philips/Sony compact disc standard was finalized. The Philips development began in 1969 with efforts by Dutch physicists Klaas Compaan and Piet Kramer to record video images in holographic form on disc. Their prototype in 1972 used a laser beam to read a track of pits as the coded FM video signal. Lou Ottens of Philips had helped develop the compact audio cassette and required that the video disc be small size. A digital PCM code was substituted for the FM signal, the disc was made of polycarbon and 115mm diameter and tracked from inside to the outside. Another prototype was demonstrated in March 1979. Sony agreed to collaborate with Philips to develop standards. The compact disc as sold to the public for $15 would be made of plastic coated with a layer of aluminum and protected with a final layer of lacquer, costing less than $1 to manufacture. The master disc was made of glass, coated with photo emulsion, exposed to laser, then etched in chemical bath leaving pits in a spiral groove. The CD rotated at variable speeds of 200 rpm near the edge to 500 rpm near the center. The size would be 120mm, use 16-bit encoding and a sampling frequency of 44,100 per second. The maximum playing time would be 74 minutes, long enough to hold Beethoven's 9th Symphony. The Philips/Sony collaboration ended in 1981 and each company released its own products based on the 1980 standard. The Sony CDP-101 compact disc player was introduced in Tokyo Oct. 1, 1982, in Europe in the fall of 1982, and in the U.S. in the spring of 1983. The first CD pressing plant in the U.S. was opened in Terre Haute IN in 1984, a center of shellac record production since the 19th century because of limestone deposits.

1980 - Sony introduced the 3.5-inch floppy disk, called a "diskette" because its rigid plastic case was no longer flexible.

1981 - At the October meeting of the AES, Dave Smith and Chet Wood from Sequential Circuits presented a paper on the Universal Synthesiser Interface that became the basis of the Musical Instrument Digital Interface (MIDI) protocol adopted August 1982 and demonstrated at the first North American Music Manufacturers show in Los Angeles in 1983. The first MIDI keyboards by Roland and Sequential Circuits, and the Yamaha DX7, were put on sale in 1983.

1982 - Tom Jung used digital audio to make direct 2-track recordings and released the first jazz CDs on his DMP label. He would later pioneer 20-bit recording in order to make full use of the CD 16-bit dynamic range with the added necessary recording headroom of 10dB and reduce the noise evident in lower amplitudes.
Sony's D-5

1984 - Sony introduced the D-5 portable compact disc player at the Japan Audio Fair and in the U.S., using the same VLSI chip and miniature laser from Sony's auto CD player, thus building a bridge in the world of portable personal music players from magnetic tape Walkman of 1979 to the DAT Walkman TCD-D3 of 1991 to the digital Discman of 1999.

1985 - Sony and Philips produced the standard for Compact Disc Read Only Memory (CD-ROM) computer discs that would use the same laser technology as the audio CD.

Sony cassette fromDAT Resource Guide
1986 - Digital Audio Tape, or DAT, introduced by Sony/Philips 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.

1987 - Dolby Pro Logic used low-cost integrated circuit chips to encode surround channel information for home speakers.

1988 - for the first time, CD sales surpassed LP sales, leaving CD and cassette as the two dominant consumer formats; more than 1/2 of TV households own a VCR; the first transatlantic fiber-optic cable carried up to 37,000 telephone transmissions and began to replace satellites for telephone communication.

1988 - Sony introduced the D-88 Pocket Discman capable of playing 3-inch compact discs (CD-Singles) introduced in 1987.

1990 - Sony and Philips produce the standard for the Recordable CD-ROM (CD-R).

M20 version of ADAT from Alesis
1991 - The Alesis Corporation of Los Angeles introduced on January 18 at National Association of Music Merchants show 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 1980s; 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."

1991 - Philips introduced on Oct. 16 the Compact Disc Interactive, or CD-I, player that plugged into a TV and played music and video from an interactive on-screen menu; Polygram Records released on of the first CD-I discs for $14.95, the "`Louis Armstrong: American Songbook," playable on a regular CD player but also with text, interviews and lyrics cued to the music, and two unreleased tracks; Tim Berners-Lee developed the World-Wide Web (WWW), an important step in the history of the Internet.

pre-recorded pits of a MiniDisc, from Sony's Rewritable MiniDisc System
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. According to The Rewritable MiniDisc System, "Sales of cassette tapes had been decreasing since 1989, and Sony felt that the compact cassette system was approaching the end of its format life."

1992 - IBM and Toshiba In July formed an alliance to develop flash memory cards. In November 1995, Toshiba introduced at the Las Vegas COMDEX show a data storage device called Solid State Floppy Disk Card (SSFDC) using 16 megabit (Mb) NAND flash electrically erasable programmable read only memory (EEPROM).

1993 - 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; see TASCAM: The First 25 Years.

1993 - Digital HDTV Grand Alliance in October selected Dolby AC-3 to provide digital surround sound for the emerging technology of digital television.
Flash Memory Card

1994 - Fox Network in August began broadcasting entire NFL season in Dolby Surround.

1994 - SanDisk in October introduced the Compact Flash memory card to store audio and visual data on cards no larger than a matchbook holding 4-106 MB of data. SanDisk and Siemens AG in 1997 patented the MultiMediaCard no larger than a postage stamp holding 2-16 MB.

1995 - In September, Sony and Toshiba reached a compromise to develop a single DVD standard by the end of the year rather than continue to develop competing DVD players.

1995 - In December the format for DVD-Video and DVD-ROM was established. "It calls for a CD-sized 5-inch (12cm) disc, 0.05 inch (1.2mm) thick, with an MPEG2-compressed storage capacity of 4.7 gigabytes per side (7.5 times that of CDs) and an average transfer speed of 4.69 megabits per second (three times faster than CDs). DVD-Video, for movies and concerts, will provide LD-like imagery while playing for 133 minutes per side. Its soundtrack will allow eight-language dubbing and 32 sets of subtitles. DVD-ROM, for computer data, will handle huge applications, enable impressive visuals, and manage hybrid software for multiple operating systems." (from Pioneer)
Walter Murch, right, and director Minghella, from Murch

1996 - Walter Murch used Sonic Solutions for the first digitally-edited Hollywood film to win an Academy Award. By 1998, Lost in Space became the first major Hollywood with an all-digitally produced soundtrack.

1996 - The AMS Neve Capricorn at Right Track Recording in New York completed the world's first 24-bit digital recording for The Pat Metheny Group's album "Quartet."

1996 - FCC on December 24 approved a digital TV standard, including HDTV

1996 - DVD players started selling in Japan, and the following year began selling in the US.

1997 - DV (Digital Video)/ miniDV standard introduced by Panasonic & Sony.

1997 - April 2 the FCC auctioned two licenses for Digital Audio Radio Service (DARS)

1997 - Norsam Technologies developed the HD-ROM to store 165 gigabytes on a single CD-size disk by using a 50-nanometer laser beam rather than the standard 800- and 350 nanometer lasers.

1997 - San Diego's was founded in November by Michael Robertson with 3,000 songs available for free download. In the next 12 months, it became the #1 music site on the Internet with 3 million hits monthly.

1998 - The first MP3 Summit was held July 2 at the UCSD Price Center in San Diego, attended by digital music leaders Scott Jamar of a2bmusic, Xing CEO Hassan Miah, music lawyer Robert Kohn, Gene Hoffman founder of Goodnoise, the first Internet music label, Geffen Records producer Jim Griffen, and Dr. Karlheinz Brandenburg, one of the founders of MP3 compression technology.

1998 - On August 6, the first HDTV set went on sale for $5,499 to the public in San Diego, a 56-inch Panasonic set that was developed at the company's research and development center in San Diego and manufactured in Tijuana.

1998 - In Sept. the DVD-Audio Working Group of the DVD Forum agreed on the DVD-Audio Format 1.0 specifications. The capacity would be the same 4.7/8.5/9.4/17 GB as DVD-Video, but the sampling rate of 88.2 kHz and 176.4 kHz will be higher for a frequency response of 0-96 kHz rather than 0-48 kHz for DVD-Video at 44.1 kHz and 5-20 kHz for the audio CD; the Maximum Transfer Rate for Audio will be 9.6 Mbps rather than 6.1 Mbps for DVD-Video or 1.4 Mbps for audio CD.

1998 - Denon introduced the first HDCD (High Definition Compact Disc) player.

President Clinton shops online 12/20/99
1999 - Panasonic July 23 press release announced DVHS (Digital-VHS), the first VCR capable of recording all 18 Digital TV format including HDTV.

1999 - Sony on September 30 in San Diego introduced SACD (Super Audio CD).

1999 - The CA*net3 fiber optic network in Canada became the fastest computer network in the world, capable of transmitting all 9 symphonies of Beethoven in .065 seconds; see speed comparison chart.


Digital Revolution Topics | Digital Audio Formats | Digital Radio | Digital Television | DVD

1999-2004 by Steven E. Schoenherr. All rights reserved.

Return to Recording Technology History | this page revised 5/5/04