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'Magnetic tape' is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. Nearly all recording tape is of this type, whether used for video, audio storage or general purpose digital data storage using a computer.
Magneto-optical and optical tape storage products have been developed using similar concepts, but have achieved little commercial success.

Contents

Audio recording

Video recording

Data storage

References

External links

Audio recording

Main articles: Magnetic tape sound recording

Magnetic tape was first invented for recording sound by Fritz Pfleumer in 1926 in Germany, based on the invention of magnetic wire recording by Valdemar Poulsen in 1898. Pfleumer's invention used an iron oxide powder coating on a long strip of paper. This invention was further developed by the German electronics company AEG, which manufactured the recording machines and BASF, which manufactured the tape. In 1933, working for AEG, Eduard Schuller developed the ring shaped tape head. Previous head designs were needle shaped and shredded the tape. An important discovery made in this period was the technique of AC biasing which dramatically improved the fidelity of the recorded audio signal.
Due to the international hostilities preceding World War II, these developments were largely kept secret from the rest of the world. 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.
A wide variety of recorders and formats have developed since.

Video recording

Main articles: Videotape

Video recording demands much higher bandwidth than audio recording and was made practical by the invention of quadruplex recording and, later, helical scan. Early video recorders were reel-to-reel but modern systems use cartridge tapes. Videocassette recorders are very common in homes and television production facilities, though many functions of the VCR are being replaced by optical disc media.

Data storage

Main articles: Magnetic tape data storage


The use of magnetic tape for data storage has been one of the constants of the computer industry. In all formats, a tape drive (or "transport" or "deck") uses precisely-controlled motors to wind the tape from one reel to another, passing a tape head as it does.
Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The recording medium was a thin strip of one half inch (12.65 mm) wide metal, consisting of nickel-plated bronze (called Vicalloy). Recording density was 128 characters per inch (198 micrometre/character) on eight tracks.
Early IBM tape drives were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long u-shaped loops of tape. When active, the two tape reels thus fed tape into or pulled tape out of the vacuum columns, intermittently spinning in rapid, unsynchronized bursts resulting in visually-striking action. Stock shots of such vacuum-column tape drives in motion were widely used to represent "the computer" in movies and television.

Most modern magnetic tape systems use reels that are much smaller than the old 10.5 inch open reels and are fixed inside a cartridge to protect the tape and facilitate handling. Many late 1970s and early 1980s home computers used Compact Cassettes encoded with the Kansas City standard. Modern cartridge formats include LTO, DLT, and DAT/DDC.
Tape remains a viable alternative to disk due to its lower cost per bit. Though the areal density is lower than for disk drives, the available surface on a tape is far greater. The highest capacity tape media are generally on the same order as the largest available disk drives (about 1 TB in 2007.) Tape has historically offered enough advantage in cost over disk storage to make it a viable product, particularly for backup, where media removability is also important. The rapid improvement in disk storage density and price, coupled with arguably less-vigorous innovation in tape storage, has reduced the market share of tape storage products.

References

External links

★ History of Tape Recording Technology

★ VidiPax Audio Format Guide