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Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic tape could with relative ease record and playback audio, visual, and binary computer data.
Magnetic tape revolutionized sound recording and reproduction and broadcasting. It allowed radio, which had always been broadcast live, to be recorded for later or repeated airing. Since the early 1950s, magnetic tape has been used with computers to store large quantities of data and is still used for backup purposes.
Magnetic tape begins to degrade after 10–20 years and therefore is not an ideal medium for long-term archival storage.
While good for short-term use, magnetic tape is highly prone to disintegration. Depending on the environment, this process may begin after 10–20 years.
Over time, magnetic tape made in the 1970s and 1980s can suffer from a type of deterioration called sticky-shed syndrome. It is caused by hydrolysis of the binder in the tape and can render the tape unusable.
Since the introduction of magnetic tape, other technologies have been developed that can perform the same functions, and therefore, replace it. Despite this, technological innovation continues. As of 2014[update] Sony and IBM continue to advance tape capacity.
Because of escalating political tensions and the outbreak of World War II, these developments in Germany were largely kept secret. Although the Allies knew from their monitoring of Nazi radio broadcasts that the Germans had some new form of recording technology, its nature was not discovered until the Allies acquired German recording equipment as they invaded Europe at the end of the war. It was only after the war that Americans, particularly Jack Mullin, John Herbert Orr, and Richard H. Ranger, were able to bring this technology out of Germany and develop it into commercially viable formats. Bing Crosby, an early adopter of the technology, made a large investment in the tape hardware manufacturer Ampex.
A wide variety of audiotape recorders and formats have been developed since. Some magnetic tape-based formats include:
- Perforated (sprocketed) film audio magnetic tape (sepmag, perfotape, sound follower tape, magnetic film)
- 8-track tape
- Compact Cassette
- RCA tape cartridge
- NT (cassette)
- Digital Audio Stationary Head
- Digital Audio Tape
- Digital Compact Cassette
Some magnetic tape-based formats include:
- Quadruplex videotape
- Ampex 2 inch helical VTR
- Type A videotape
- IVC videotape format
- Type B videotape
- Type C videotape
- Video Cassette Recording
- Video 2000
- VX (videocassette format)
- Compact Video Cassette
- M (videocassette format)
- MII (videocassette format)
- D-1 (Sony)
- DCT (videocassette format)
- D-2 (video)
- D-3 (video)
- D5 HD
- D6 HDTV VTR
Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The system's UNISERVO I tape drive used a thin strip of one-half-inch (12.65 mm) wide metal, consisting of nickel-plated bronze (called Vicalloy). The recording density was 100 characters per inch (39.37 characters/cm) on eight tracks.
In 2014, Sony and IBM announced that they had been able to record 148 gigabits per square inch with magnetic tape media developed using a new vacuum thin-film forming technology able to form extremely fine crystal particles, allowing true tape capacity of 185 TB.
- Analog recording
- Magnetic developer
- Print-through – Transfer of content between magnetic tape layers
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