Magnetic Tape

Definition: Magnetic Tape

Magnetic Tape

Noun

1. Memory device consisting of a long thin plastic strip coated with iron oxide; used to record audio or video signals or to store computer information; "he took along a dozen tapes to record the interview".

Specialty Definitions: Magnetic Tape

Domain	Definitions
Computing	Magnetic tape (Or "magtape", "tape" - paper tape is now obsolete) A data storage medium consisting of a magnetisable oxide coating on a thin plastic strip, commonly used for backup and archiving. Early industry-standard magnetic tape was half an inch wide and wound on removable reels 10.5 inches in diameter. Different lengths were available with 2400 feet and 4800 feet being common. DECtape was a variation on this " round tape". In modern magnetic tape systems the reels are much smaller and are fixed inside a cartridge to protect the tape and for ease of handling ("square tape" - though it's really rectangular). Cartridge formats include QIC, DAT, and Exabyte. Tape is read and written on a tape drive (or "deck") which winds the tape from one reel to the other causing it to move past a read/write head. Early tape had seven parallel tracks of data along the length of the tape allowing six bit characters plus parity written across the tape. A typical recording density was 556 characters per inch. The tape had reflective marks near its end which signaled beginning of tape (BOT) and end of tape (EOT) to the hardware. Data is written to tape in blocks with inter-block gaps between them. Each block is typically written in a single operation with the tape running continuously during the write. The larger the block the larger the data buffer required in order to supply or receive the data written to or read from the tape. The smaller the block the more tape is wasted as inter-block gaps. Several logical records may be combined into one physical block to reduce wastage (" blocked records"). Finding a certain block on the tape generally involved reading sequentially from the beginning, in contrast to magnetic disks. Tape is not suitable for random access. The exception to this is that some systems allow tape marks to be written which can be detected while winding the tape forwards or rewinding it at high speed. These are typically used to separate logical files on a tape. Most tape drives now include some kind of data compression. There are several algorithms which provide similar results: LZ (most), IDRC (Exabyte), ALDC (IBM, QIC) and DLZ1 (DLT). See also cut a tape, flap, Group Code Recording, spool, macrotape, microtape, Non Return to Zero Inverted, Phase Encoded. (1997-04-05). Source: The Free On-line Dictionary of Computing.
Aerospace	A ribbon of paper, metal, or plastic, coated or impregnated with magnetic material on which information may be stored in the form of magnetically polarized areas. (references)
Source: compiled by the editor from various references; see credits.

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Specialty Definition: Magnetic tape

(From Wikipedia, the free Encyclopedia)

Magnetic tape is an information storage medium consisting of a magnetisable oxide coating on a thin plastic strip. Nearly all recording tape is of this type, whether used for video with a video cassette recorder, audio storage (reel-to-reel tape, compact audio cassette, digital audio tape (DAT) and other formats including 8-track cartridges) or general purpose digital data storage using a computer (specialized tape formats, as well as the above-mentioned compact audio cassette, used with home computers of the 1980s, and DAT,used for backup in workstation installations of the 1990s).

Magnetic Tape Audio Storage

From the late 1940s through the 1970s, (analog) magnetic tape was the predominant and the highest quality sound recording techology available.

Magnetic recording had been demonstrated in principle as early as 1898 by Valdemar Poulsen in his telegraphone. With electronic amplification, the telegraphone evolved into wire recorders which were popular for voice recording and dictation during the 1940s and into the 1950s. The reproduction quality of wire recorders was low, however—significantly lower than that achievable with phonograph disk recording technology. Wire recorders could not prevent the wire from undergoing axial twisting, and hence could not insure that the wire was oriented the same way during recording and playback. When oriented the wrong way, high frequencies were reduced and the sound was muffled. The hysteresis of the steel material resulted in nonlinear transfer characteristics, manifesting as distortion. There were other practical difficulties, such as the tendency of the wire to become tangled or snarled. Splicing could be performed by knotting together the cut wire ends, but the results were not very satisfactory.

Magnetic tape recording as we know it today was developed in Germany during the late 1930s by the C. Lorenz company. In 1938, S. J. Begun left Germany and joined Brush Development Company in the United States, where work continued but attracted little attention. During the war, the Allies became aware of radio broadcasts that seemed to be transcriptions, but whose audio quality was indistinguishable from that of a live broadcast. After the war, the Allied capture of a number of German Magnetophon recorders from Radio Luxembourg aroused great interest. These recorders incorporated all of the key technological features of analog magnetic recording, particular the use of high-frequency "bias."

Development of magnetic tape recorders in the late 1940s and early 1950s is associated with the Brush Development Corporation and its licensee, Ampex; the equally important development of magnetic tape media itself was led by Minnesota Mining and Manufacturing corporation (now known as 3M).

The use of magnetic tape recorders in broadcasting got a significant boost from Bing Crosby, who refused to perform on radio unless his shows could be prerecorded.

7-1/2" reel of 1/4" recording tape
Typical of audiophile/consumer/educational use 1950s/60s

The typical professional tape recorder of the early 1950s used 1/4" wide tape on 10-1/2" reels, with a capacity of 2400'. Typical speeds were initially 15 inches per second (ips) yielding 30 minutes' recording time on a 2400' reel. 30 ips was used for the highest quality work.

Standard tape speeds varied by factors of two. 30 and 15 ips were used for professional audio recording; 7-1/2 ips for home audiophile prerecorded tapes; 7-1/2 and 3-3/4 ips for audiophile and consumer recordings (typically on 7" reels). 1-7/8 ips and occasionally even 15/16 ips were used for voice, dictation, and applications where very long recording times were needed (such as logging police and fire department calls).

The key electronic invention that made high-quality audio tape recording possible was the development of so-called "bias." Bias is a high-frequency signal, typically in the range of 50 to 150 kHz, which is added to the signal to be recorded before being applied to the recording head. Bias enables a linear transfer function to be obtained from the highly nonlinear magnetic recording medium. In effect, the bias causes the magnetization to be performed at levels that are in the most nearly linear portion of the medium's transfer function. As the tape leaves the head, the bias current partially demagnetizes the tape and the remaining net induction is essentially the difference between the positive and negative half-cycles of the previously recorded. This differencing operation further cancels some of the nonlinearity.

Magnetic audio tape can be easily and inaudibly spliced, a fact which revolutionized audio recording. Multiple tracks could easily be recorded simultaneously (on a wide tape), and played back with perfect synchronization; this, too was revolutionary. It became common studio recording practice to record on multiple tracks, and mix down afterwards. The convenience of tape editing and multitrack recording led to the rapid adoption of magnetic tape as the primary technology for commercial musical recordings. Although 33-1/2 rpm and 45 rpm vinyl phonograph disks were the dominant consumer format, recordings were customarily made first on tape, then transferred to disk.

Analog magnetic tape recording introduces noise, usually called "hiss", caused by the finite size of the magnetic particles in the tape. There is a direct tradeoff between noise and economics. Signal-to-noise ratio is reduced at higher speeds and with wider tracks, increased at lower speeds and with narrower tracks.

By the late 1960s, disk reproducing equipment became so good that audiophiles soon became aware that some of the noise audible on recordings was not surface noise or deficiencies in their equipment, but reproduced tape hiss. A few companies starting making "direct to disk" specialty recordings, made by feeding microphone signals directly to a disk cutter (after amplification and mixing). These recordings never became popular, but they dramatically demonstrated the magnitude and importance of the tape hiss problem.

In the 1970s, advances in solid-state electronics were making the design and marketing of more sophisticated analog circuitry economically feasible. This led to a number of attempts to reduce tape hiss through the use of various forms of volume compression and expansion, the most notable and commercially successful being several systems developed by Dolby Laboratories. These systems divided the frequency spectrum into multiple bands and applied volume compression/expansion independently to each band. The Dolby systems were very successful at increasing the effective dynamic range and signal-to-noise ratio of analog audio recording; to all intents and purposes, audible tape hiss could be eliminated.

In the 1980s, digital recording methods were introduced, and analog tape recording was gradually displaced.

Magnetic Tape Video Storage

Magnetic Tape Data Storage

half-inch reel tape

Magnetic tape was first used to record data in 1951 on the Mauchly-Eckert Univac. The recording medium was a thin band of solid steel. Recording density was 128 characters per inch at a linear speed of 100 ips, yielding a data rate of 12800 characters per second.

IBM computers of the late 1950s used oxide-coated tape similar to that used in audio recording, and IBM's technology soon became the de facto industry standard. Magnetic tape was half an inch wide and wound on removable reels 10.5 inches in diameter. Different lengths were available with 2400 feet and 4800 feet being common.

IBM's drives were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long loops of tape. Powerful reel motors activated the reels as necessary to maintain the length of the tape loop in each column within set limits. The two reels thus spun in rapid, uneven and unsynchronized bursts of motion which were eye-catching and dramatic. Stock shots of vacuum-column tape drives came to symbolize "the computer" in movies and television.

LINCtape (and its derivative, DECtape) were variations on this "round tape." They were essentially a personal storage medium. They featured a fixed formatting track which, unlike standard tape, made it feasible to read and rewrite blocks repeatedly in place. LINCtapes and DECtapes had similar capacity and data transfer rate to the diskettes that displaced them, but their "seek times" were on the order of thirty seconds to a minute.

Most modern magnetic tape systems use reels that are reels are much smaller and are fixed inside a cartridge to protect the tape and facilitate handling. Cartridge formats include QIC, DAT, and Exabyte.

cartridge tapes in drives

Tape is read and written on a tape drive (or "deck") which winds the tape from one reel to the other causing it to move past a read/write head. Early tape had seven parallel tracks of data along the length of the tape allowing six bit characters plus parity written across the tape. A typical recording density was 556 characters per inch. The tape had reflective marks near its end which signaled beginning of tape (BOT) and end of tape (EOT) to the hardware.

Data is typically written to tape in blocks with inter-block gaps between them. Each block is typically written in a single operation with the tape running continuously during the write. There is a complex tradeoff between block size, the size of the data buffer in the record/playback deck, the percentage of tape lost on inter-block gaps, and read/write throughput.

Tape has quite a long data latency for random accesses since the deck must wind an average of 1/3 the tape length to move from one arbitrary data block to another. Tape remains a viable alternative to disk due to its higher bit density and cost per bit. Tape has historically offered enough advantage in these two areas above disk stroage to make it a viable product. The recent vigorous innovation in disk storage density and price, coupled with less-vigorous innovation in tape storage, has reduced the viability of tape storage products.

Most tape systems attempt to alleviate the intrinsic long latency using eitheer indexing, whereby a separate lookup table is maintained which gives the physical tape location for a given data block number, or marking, whereby a tape mark that can be detected while winding the tape at high speed.

Most tape drives now include some kind of data compression. There are several algorithms which provide similar results: LZ (Most), IDRC (Exabyte), ALDC (IBM, QIC) and DLZ1 (DLT). The actual compression algorithms used are not the most effective known today, and better results can usually be obtained by turning off the compression built into the device and using a software compression program instead.

This article (or an earlier version of it) contains material from FOLDOC, used with permission.

Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Magnetic tape."

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Abbreviations & Acronyms: Magnetic Tape

The following table is compiled from various sources, across various languages. When English abbreviations or acronyms come from a non-English source, this is noted.
Entry	Source	Expression	Field
MATER	English	Magnetic tape exchange format for Terminological and Lexicographical Records	Computing, Language
Source: compiled by the editor, based on several corpora (additional references).

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Synonyms: Magnetic Tape

Synonyms: mag tape (n), tape (n). (additional references)

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Crosswords: Magnetic Tape

English words defined with "magnetic tape": audiotape ♦ cassette, cassette tape ♦ magnetic head ♦ splice, splicer, splicing ♦ tape, tape cartridge, tape drive, tape machine, tape recorder, tape recording, tape transport, taping, transport ♦ VCR, videocassette recorder, videotape. (references)

Specialty definitions using "magnetic tape": Advanced Intelligent Tape, AMA subsystem, automatic message accounting subsystem ♦ blocked records ♦ cartridge loader, cassette tape holder, CCT, comparing control, COMPUTER PERIPHERAL EQUIPMENT OPERATOR, cut a tape ♦ DAS commands, DAS tape, DATA ENTRY CLERK, data entry operator, DECtape, diagnostic medical sonographe, Digital Audio Tape, digital component technology, Digital Linear Tape, DIGITIZER OPERATOR, disk/tape copy utility ♦ electronic funds transfer, ELECTRONIC INTELLIGENCE OPERATIONS SPECIALIST, EOT, external memory ♦ Film Optical Sensing Device for Input to Computers, FOSDIC ♦ hard tape errors, HOLTER SCANNING TECHNICIAN, holter technicia ♦ interrecord gap ♦ JIG-BORING MACHINE OPERATOR, NUMERICAL CONTROL ♦ Kalkkruste, Kom-90 ♦ macrotape, magnetic tape cartridge, magnetic tape cassette, magnetic tape deck, magnetic tape drive, magnetic tape leader, magnetic tape recording, magnetic tape transport mechanism, magnetic tape unit, MAGNETIC-TAPE WINDER, main memory ♦ non-volatile storage ♦ PHOTOCOMPOSING-MACHINE OPERATOR, physical file, PHYSICAL MEDIUM, playback operator, PROBE TEST EQUIPMENT TECHNICIAN, SEMICONDUCTOR WAFERS, proof clerk, PROOF-MACHINE OPERATOR, PROP ATTENDANT ♦ Quarter Inch Cartridge ♦ readout, record gap, rewind, rewinder, round tape, ROUTER SET-UP OPERATOR, NUMERICAL CONTROL, rusty memory ♦ SECTION-PLOTTER OPERATOR, seismometer or seismograph, Simultaneous Peripheral Operation On-Line, stack loader, Storage Management Services, SYSTEMS PROGRAMMER ♦ TAPE BLOCK, tape head, TAPE LIBRARIAN, tape magazine, tape station, tape unit, transit clerk ♦ ULTRASOUND TECHNOLOGIST ♦ video band, video disk player, video player, video tape, video-tape, Videotape Recording ♦ wind back. (references)

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Commercial Usage: Magnetic Tape

Domain	Title
Books	Digital magnetic tape recording for computer applications (reference) Gale Directory of Databases 2002: Cd-Rom, Diskette, Magnetic Tape, Handheld and Batch Access Database Products (reference) International guide to MARC databases and services : national magnetic tape and online services (reference) Magnetic Tape Librarian (reference) Magnetic Tape Recording for the Eighties (reference) (more book examples)

Periodicals	Ercb Core Analysis - Magnetic Tape (reference) Address On Magnetic Tape - National Ed (reference) (more periodical examples)
Source: compiled by the editor from various references; see credits.

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Photo Album: Magnetic Tape

Thumbnail	Description & Credit
	[James Goldsmith standing in front of the magnetic tape control unit].Credit: National Library of Medicine.
Source: compiled by the editor from various references; see credits.

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Non-Fiction Usage: Magnetic Tape

Subject	Topic	Quote
Business		China is a large producer of magnetic tape, floppy discs, and magnetic powder. (references)
Source: compiled by the editor from ICON Group International, Inc.; see credits.

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Expressions: Magnetic Tape

Expressions using "magnetic tape": magnetic tape cartridge ♦ magnetic tape cassette ♦ magnetic tape deck ♦ magnetic tape drive ♦ magnetic tape leader ♦ magnetic tape recording ♦ magnetic tape reel ♦ magnetic tape trailer ♦ magnetic tape transport mechanism ♦ magnetic tape unit. Additional references.
Source: compiled by the editor from various references; see credits.

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Frequency of Internet Keywords: Magnetic Tape

The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com.

Expression	Frequency per Day
magnetic tape	84
magnetic tape eraser	4
magnetic tape recording	4
magnetic tape typewriter	3
magnetic tape drive	3
machine magnetic tape	2
magnetic tape measure	2
Source: compiled by the editor from various references; see credits.

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Modern Translations: Magnetic Tape

Language		Translations for "magnetic tape"; alternative meanings/domain in parentheses.
Chinese		磁帶 . (various references)

Danish		magnetbånd (tape). (various references)

Dutch		magnetiseerbare band (tape), magnetiseerbaar lint (tape), magnetische band (tape), magneetband (tape). (various references)

Finnish		magneettinauhayksikkö (magnetic tape deck, magnetic tape drive, magnetic tape transport mechanism, magnetic tape unit, tape deck, tape drive, tape station, tape transport, tape unit), magneettinauhakasetti (cassette, magnetic tape cassette), magneettinauha-asema (magnetic tape deck, magnetic tape drive, magnetic tape transport mechanism, magnetic tape unit, tape deck, tape drive, tape station, tape transport, tape unit), tallennus nauhalle (magnetic tape recording, tape recording), nauhoitus (magnetic tape recording, tape recording, taped recording), lopuke (leader, magnetic tape trailer, trailer), kasetti (cartridge, casette, cassette, cassette tape holder, magnetic tape cassette, tape cartridge, tape magazine), alkunauha (leader, magnetic tape trailer, trailer). (various references)

French		bande magnétique. (various references)

German		Magnetband (magtape, tape). (various references)

Greek		μαγνητική ταινία (tape). (various references)

Hungarian		mágnesszalag. (various references)

Italian		nastro magnetico (audio tape, tape), banda magnetica (tape). (various references)

Japanese Kanji		録音テープ (audio tape). (various references)

Japanese Katakana		ろくお�"テープ (audio tape). (various references)

Pig Latin		agneticmay apetay.(various references)

Portuguese		leitor magnético, fita magnética (magnetism, tape), banda magnética (tape, video band, video tape, videotape, video-tape). (various references)

Spanish		cinta magnética (tape, video band, video tape, videotape, video-tape). (various references)

Swedish		magnetband. (various references)

Vietnamese		băng ghi âm. (various references)
Source: compiled by the editor from various translation references.

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Anagrams: Magnetic Tape

Scrabble® Enable2K-Verified Anagrams
	Words within the letters "a-a-c-e-e-g-i-m-n-p-t-t"
	-2 letters: emancipate.
	-3 letters: emittance, magnetite, pectinate, pegmatite.
	-4 letters: agenetic, agminate, apatetic, campagne, campaign, capitate, catamite, catenate, emaciate, enigmata, geminate, magnetic, paginate, pancetta, patience, patinate, pittance, tegmenta, tempting.
	-5 letters: acetate, agamete, agapeic, agitate, agnatic, amentia, anaemic, animate, apatite, camping, captain, catenae, catmint, catting, cementa, centime, emanate, enemata, epigean, etamine, gametic, gateman, gatemen, genetic, magenta, magnate, manatee, matinee, matting, meeting, mintage, nametag, nematic, nictate, pageant, patient, patinae, patting, peacing, pectate, pemican, petting, picante, pigment, taeniae, tamping, teaming, teatime, teeming, tegmina, temping, tentage, tetanic, timpana.
Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro.