Talk:Magnetic tape/Archive 1

6250 bpi, 3200 bpi
Anyone have information on the recording techniques used for 6250 bpi and 3200 bpi 9-track tapes? The 3200 format is described as "Double Phase Encoding"; I think it may be the same as 1600 only denser (as some tape drives can do 3200 bpi) but I'm not sure. The 6250 format is called GCR, but in this case that's an error-correction code. I'd like to know what the actual recording technique was (NRZi, maybe?). One reference states that a 6250 bpi tape had over 9000 flux transitions per inch, but the numbers don't add up for either PE or NRZi (6250 * 8/7 = 7142 takes the error correction code into account if it's NRZi). There's an ANSI standard (X3.54) but I'm too cheap to buy it for curiosity's sake. Nybbler 20:21, 2 March 2006 (UTC)

Nevermind... found it. It's RLL(0,2), which is a rate 5/4 code. And 4 synchronization codes are inserted every 316 data codes, which gives 6250 * 8/7 * 5/4 * 320/316 = (approx) 9042. Nybbler 15:33, 6 March 2006 (UTC)

Removing Link
I am looking for information about the process of magnetic recording. What I get when I click on this link (at "Guitarz-for-ever"), besides advertisement links, direct product links, and links for "Eddie Van Halen" and "Motivation to Acheive Success", is seven basic paragraphs on the evolution of recording. If there is any appropriate information, i.e. information concerning the subject of this encyclopedia article, it is not directly accessible. Renfield 16:08, 19 June 2006 (UTC)

Video recording: "Live" time-shifting
An IP editor inserted the following after the article's mention of "live" time-shifting possible with digital video recording:

(? What does this mean? VCRs can time shift on-the-fly, so it can't mean that. Is it referring to play-while-record?)

Yes, it is. As I noted in the edit summary, "instant replay" was an early example: Play back an earlier portion of the recording while continuing to record live. Perhaps a better word or term can be found here than "live time-shifting". And I might as well also mention that "instant replay" isn't really the best example, either, because that was first done with an analog video disc recorder such as an Ampex HS-100. Jeh (talk) 05:13, 23 September 2008 (UTC)

BTW, to the IP editor: Please don't insert questions in the visible text in the article. Embedded comments will get the attention of anyone watching the article but won't bother readers. Or, you can use the article talk page. Thanks! Jeh (talk) 05:32, 23 September 2008 (UTC)

== Article needs to include more information on the many materials used for the tape itself, and specially for the magnetic coating; as well as information on the protective coatings, information on the deterioration mechanisms and more on the aging of tapes. Common tape widths and lenghts are not included. Audio "Print-through" is not mentioned also. As it is now, the page is very incomplete. amclaussen. ==


 * There should also be mention of capacities that have been recently achieved - LTO-3, 800GB compressed. -Tapeman (16:24, 17 March 2005)


 * This (info about materials and their deterioration) is what I hoped to find in this article. Hopefully at least some of this is included in the articles about specific formats. 165.225.38.83 (talk) 16:23, 4 January 2018 (UTC)

Uncited material in need of citations
I am moving the following uncited material here until it can be properly supported with inline citations of reliable, secondary sources, per WP:V, WP:NOR, WP:CS, WP:NOR, WP:IRS, WP:PSTS, et al. This diff shows where it was in the article. Nightscream (talk) 18:20, 27 August 2022 (UTC)


 * I have reverted this and have started addressing tags previously added by Nightscream. Additional context on this editing pattern can be found at Talk:Radio and User_talk:Nightscream. ~Kvng (talk) 16:36, 28 August 2022 (UTC)

LEDE SECTION
A device that stores computer data on magnetic tape is known as a tape drive.

It allowed gramophone records to be recorded in multiple parts, which were then mixed and edited with tolerable loss in quality. It was a key technology in early computer development, allowing unparalleled amounts of data to be mechanically created, stored for long periods, and rapidly accessed. The video tape recorder allowed television stations to gather news, timeshift and record content without having to use or develop relatively expensive film stock; unlike film stock, videotape may be reused.

Construction
Magnetic tape is usually recorded on only one side. The back side is a substrate that gives the tape strength and flexibility. The magnetic side or recording layer of most tapes is typically a metallic oxide called the , which is magnetized by a tape head to store the information. The magnetic material originally used in this layer was iron oxide, though chromium dioxide and other materials such as metal particles and barium ferrite have been used at times, such as in Type II and Type IV compact cassettes and LTO tapes. An adhesive binder mixed with the recording material adheres to the substrate. A lubricant is normally applied at the factory to minimize head and tape wear.

In all tape formats, a tape drive or tape transport uses one or more motors to wind the tape from one reel to another, enabling locating, recording and playback of recorded content by passing the tape over tape heads to read, write or erase as it moves.

Magnetic tapes are packaged in both open-reel and cartridge and cassette formats.

Audio
Magnetic tape was invented for recording sound by Fritz Pfleumer in 1928 in Germany, based on the invention of magnetic wire recording by Oberlin Smith in 1888 and Valdemar Poulsen in 1898. Pfleumer's invention used a ferric 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, at the time a division of IG Farben, which manufactured the tape. In 1933, working for AEG, Eduard Schuller developed the ring-shaped tape head. Previous head designs were needle-shaped and tended to shred the tape. Another important discovery made in this period was the technique of AC biasING, which improved the fidelity of the recorded audio signal by increasing the effective linearity of the recording medium.

Digital recording to flash memory and hard disk has largely supplanted magnetic tape for most purposes. However, tape remains a common parlance for the recording process.

Video


The practice of recording and editing audio using magnetic tape rapidly established itself as an obvious improvement over previous methods. Many saw the potential of making the same improvements in recording the video signals used by television. Video signals use more bandwidth than audio signals. Existing audio tape recorders could not practically capture a video signal. Many set to work on resolving this problem. Jack Mullin (working for Bing Crosby) and the BBC both created crude working systems that involved moving the tape across a fixed tape head at very high speeds. Neither system saw much use. It was the team at Ampex, led by Charles Ginsburg, that made the breakthrough of using a spinning recording head and normal tape speeds to achieve a very high head-to-tape speed that could record and reproduce the high bandwidth signals of video. The Ampex system was called Quadruplex and used 2 in tape, mounted on reels like audio tape, which recorded the signal in what is now called transverse scan.

Later improvements by other companies, particularly Sony, led to the development of helical scan and the enclosure of the tape reels in an easy-to-handle videocassette cartridge. Nearly all modern videotape systems use helical scan and cartridges. Videocassette recorders (VCRs) used to be common in homes and television production facilities, but many functions of the VCR have been replaced with more modern technology. Since the advent of digital video and computerized video processing, optical disc media and digital video recorders can now perform the same role as videotape. These devices also offer improvements like random access to any scene in the recording and the ability to pause a live program and have replaced videotape in many situations.

Computer data
Early IBM 7 track tape drives were floor-standing and used vacuum columns to mechanically buffer long U-shaped loops of tape. The two tape reels visibly fed tape through the columns, intermittently spinning 10.5 inch open reels in rapid, unsynchronized bursts, resulting in visually striking action. Stock shots of such vacuum-column tape drives in motion were widely used to represent mainframe computers in movies and television.

Most modern magnetic tape systems use reels that are much smaller than the 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, or alternate encodings. Modern cartridge formats include LTO, DLT, and DAT/DDC.

Tape remains a viable alternative to disk in some situations due to its lower cost per bit. Though the areal density of tape is lower than for disk drives, the available surface area on a tape is far greater. The highest capacity tape media are generally on the same order as the largest available disk drives (about 5 TB ). Tape has historically offered enough advantage in cost over disk storage to make it a viable product, particularly for backup, where media removability is necessary.

Tape has the benefit of a comparatively long duration during which the media can be guaranteed to retain the data stored on the media. Fifteen (15) to thirty (30) years of archival data storage is cited by manufacturers of modern data tape such as Linear Tape-Open media.

Linear Tape-Open is a magnetic tape-based medium used in computer systems for data backup, since it provides large capacities at a low cost, and works differently than common hard drives or solid-state drives, reducing the chance of it failing due to similar reasons.