Magnetic Storage

Information about Magnetic Storage

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Magnetic storage and magnetic recording are terms from engineering referring to the storage of data on a magnetised medium. Magnetic storage uses different patterns of magnetization in a magnetizable material to store data and is a form of non-volatile memory. The information is accessed using one or more read/write heads. As of 2007, magnetic storage media, primarily hard disks, are widely used to store computer data as well as audio and video signals. In the field of computing, the term magnetic storage is preferred and in the field of audio and video production, the term magnetic recording is more commonly used. The distinction is less technical and more a matter of preference.

History

Magnetic storage was first suggested by Oberlin Smith in 1888. The first working magnetic recorder was invented by Valdemar Poulsen in 1898. Poulsen's device recorded a signal on a wire wrapped around a drum. In 1928, Fritz Pfleumer developed the first magnetic tape recorder. Early magnetic storage devices were designed to record analog audio signals. Modern magnetic storage devices are designed for recording digital data.

In early computers, magnetic storage was also used for primary storage in a form of magnetic drum, or core memory, core rope memory, thin film memory, twistor memory or bubble memory. Also unlike modern computers, magnetic tape was often used for secondary storage.

Technical details

Access method

Magnetic storage media can be classified as either sequential access memory or random access memory although in some cases the distinction is not perfectly clear. In the case of magnetic wire, the read/write head only covers a very small part of the recording surface at any given time. Accessing different parts of the wire involves winding the wire forward or backward until the point of interest is found. The time to access this point depends on how far away it is from the starting point. The case of ferrite-core memory is the opposite. Every core location is immediately accessible at any given time.

Hard disks and modern linear serpentine tape drives do not precisely fit into either category. Both have many parallel tracks across the width of the media and the read/write heads take time to switch between tracks and to scan within tracks. Different spots on the storage media take different amounts of time to access. For a hard disk this time is typically less than 10 ms, but tapes might take as much as 100 s.

Current usage

As of 2007, common uses of magnetic storage media are for computer data mass storage on hard disks and the recording of analog audio and video works on analog tape. Since much of audio and video production is moving to digital systems, the usage of hard disks is expected to increase at the expense of analog tape. Digital tape and tape libraries are popular for the high capacity data storage of archives and backups. Floppy disks see some marginal usage, particularly in dealing with older computer systems and software. Magnetic storage is also widely used in some specific applications, such as bank checks (MICR) and payment cards (mag stripes).

Future

A new type of magnetic storage, called MRAM, is being produced that stores data in magnetic bits based on the GMR effect. Its advantage is non-volatility, low power usage, and good shock robustness. However, with storage density and capacity orders of magnitude smaller than e.g. an HDD, MRAM is a niche application for situations where small amounts of storage with a need for very frequent updates (>10**15 writes) are required, which flash memory could not support.

External links

Selected History of Magnetic Recording
Oberlin Smith and the Invention of Magnetic Sound Recording
History of Magnetic Recording on the UC San Diego web site (CMRR).
A Chronology of Magnetic Recording.
MRAM information site

• • [ e] Magnetic storage media
Wire (1898) • Tape (1928) • Drum (1932) • Ferrite core (1949) • Hard disk (1956) • Stripe card (1956) MICR (1956) • Thin film (1962) • CRAM (1962) Twistor (~1968) • Floppy disk (1969) • Bubble (~1970) • MRAM (2003)

Engineering is the applied science of acquiring and applying knowledge to design, analysis, and/or construction of works for practical purposes. The American Engineers' Council for Professional Development, also known as ECPD,^[1] (later ABET ^[2]
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For other uses, see Data (disambiguation).

Debt, AIDS, Trade in Africa (or DATA) is a multinational non-government organization founded in January 2002 in London by U2's Bono along with Bobby Shriver and activists from the Jubilee 2000 Drop
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magnet is a material or object that produces a magnetic field. A "hard" or "permanent" magnet is one which stays magnetized for a long time, such as magnets often used in refrigerator doors.
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Magnetization is a property of some materials (e.g. magnets) that describes to what extent they are affected by magnetic fields, and also determines the magnetic field that the material itself creates. Magnetization is defined as the amount of magnetic moment per unit volume.
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Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered.
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Disk read/write heads are mechanisms that read data from or write data to disk drives. The heads have gone through a number of changes over the years.

In a hard drive, the heads 'fly' above the disk surface with clearance of as little as 3 nanometres.
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Hard disk drive

An IBM hard disk drive with the metal cover removed. The platters are highly reflective.
Date Invented: September 13 1956
Invented By: An IBM team led by Reynold Johnson
Connects to:
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In computer science, data is any information in a form suitable for use with a computer^[1]. Data is often distinguished from programs. A program is a set of instructions that detail a task for the computer to perform.
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Sound is a disturbance of mechanical energy that propagates through matter as a wave (through fluids as a compression wave, and through solids as both compression and shear waves).
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Video (Latin for "I see", first person singular present, indicative of videre, "to see") is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
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Oberlin Smith (1840-1926) was an engineer who published one of the earliest works dealing with magnetic recording in 1888. In an article that appeared in the British magazine - Electrical World
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Valdemar Poulsen (November 23, 1869, in Copenhagen – July 23, 1942) was a Danish engineer. He developed a magnetic wire recorder in 1899.

The magnetic recording was demonstrated in principle as early as 1898 by Valdemar Poulsen in his Telegraphone.
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signal is any time-varying quantity. Signals are often scalar-valued functions of time (waveforms), but may be vector valued and may be functions of any other relevant independent variable.

The concept is broad, and hard to define precisely.
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An analog or analogue signal is any time continuous signal where some time varying feature of the signal is a representation of some other time varying quantity. It differs from a digital signal in that small fluctuations in the signal are meaningful.
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A digital system is one that uses discrete values (often electrical voltages), representing numbers or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous range of values (ie, as in an analog system).
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Drum memory was an early form of computer memory that was widely used in the 1950s and into the 1960s, invented by Gustav Tauschek in 1932 in Austria. For many machines, a drum
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Magnetic core memory, or ferrite-core memory, is an early form of computer memory. It uses small magnetic ceramic rings, the cores, to store information via the polarity of the magnetic field they contain.
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Core rope memory is a form of read-only memory (ROM) for computers, first used by early NASA Mars probes and then in the Apollo Guidance Computer (AGC) designed by MIT and built by Raytheon.
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Thin film memory is a high-speed variation of core memory developed by Sperry Rand in a government-funded research project.

Instead of threading individual ferrite cores on wires, a thin film (4 millionths of an inch thick) of iron-nickel alloy (called permalloy) was
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Twistor is a form of computer memory, similar to core memory, formed by wrapping magnetic tape around a current-carrying wire. Although the developers, Bell Labs, had high hopes for Twistor, it was used for only a brief time in the marketplace between about 1968 and the mid-1970s.
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Bubble memory is a type of non-volatile computer memory that uses a thin film of a magnetic material to hold small magnetized areas, known as bubbles, which each store one bit of data.
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In computing, sequential access memory (SAM) is a class of data storage devices that read their data in sequence. This is in contrast to random access memory (RAM) where data can be accessed in any order. Such devices are usually a form of magnetic memory.
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Dynamic RAM (DRAM) modules

Two 512 MB DRAM Modules

Connects to:

PCB or motherboard via one of

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Magnetic tape is a medium for magnetic recording generally consisting of a thin magnetizable coating on a long and narrow strip of plastic. Nearly all recording tape is of this type, whether used for recording audio or video or for computer data storage.
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Magnetic tape has been used for data storage for over 50 years. In this time, many advances in tape formulation, packaging, and data density have been made. Modern magnetic tape is most commonly packaged in cartridges and cassettes.
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tape library, sometimes called a tape silo, or tape jukebox, is a storage device which contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges and an automated method for loading tapes (a robot).
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Floppy Disk Drive

8 inch, 5 ¼ inch, and 3.5 inch drives
Date Invented: 1969 (8 inch), 1976 (5 ¼ inch), 1983 (3.5 inch)
Invented By: IBM team led by David Noble
Connects to:
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A magnetic stripe card is a type of card capable of storing data by modifying the magnetism of tiny iron-based magnetic particles on a band of magnetic material on the card.
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This article contains information about scheduled or expected .
It may contain preliminary or speculative information, and may not reflect the final specification of the product.
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