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Micro Drives

Terence O’Kelly

From cave walls to stone tablets to papyrus to photographic film to laser devices, storage

technology has always come up with new ways to hold and preserve information. We

often overlook the fact that sometimes older methods coexist with the latest innovations

simply because the older methods have advantages that cannot be ignored. In the

electronic age, paper is in greater use than ever before in human history. For digital

storage, magnetic recording—considered by many to be dying with tape—still leads the

way in the greatest advances in storage capacity. The new Memorex Mega TravelDrive

takes advantage of these latest advances to offer capacities beyond flash drives in a more

affordable package.

PIONEERS OF MAGNETIC RECORDING

Thomas Edison was the first to record sound, using wax cylinders and a recorder

patented in 1877. Oberlin Smith, a mechanical engineer from New Jersey, visited Edison

the following year and that same year proposed the first methods of magnetic recording

on undefined media. Valdemar Poulsen of Denmark actually produced a magnetic audio

recorder in 1893 using steel wire as the medium, and in 1934 German engineers began

making magnetic tape, the most commonly recognized form of magnetic media. Edison’s

wax cylinders waned in the face of Emil Berliner’s flat platters, the shape copied by vinyl

records, CDs, and DVDs. This platter shape was also used for magnetic media; but these

media were hidden from view in vinyl jackets (diskettes), plastic cases (micro diskettes),

and sealed cases (hard drives and disk packs). Optical discs have now replaced

diskettes and tape in common use. In time they, too, will yield to new challengers from

the future—holographic storage for optical storage, solid-state for electronic storage, and

advanced hard discs for magnetic storage using the same principles proposed by Oberlin

Smith.

PRINCIPLES OF MAGNETIC RECORDING

The basic principles behind magnetic recording are simple: all magnets have two poles--

one with a positive charge and one with a negative charge.

The charges are best

defined when the poles are separated from each other as far as possible, as in a long, thin

bar. When the “bar” is a microscopic crystal with a single magnetic domain, it is

impossible to eliminate or reduce the magnetic charge on the crystal. It is magnetic

forever. It is possible, however, to reverse the charge so that the negative pole of the

crystal becomes the positive pole and the positive pole becomes negative. A powerful

magnetic field can force or coerce the poles to switch. The stronger the charge on the

crystal, the harder it is to coerce the change in polarity; and the measurement of the

The ancient Greeks rubbed amber, fossilized sap, to put a static charge on it. Small rods of

statically charged amber floating on water worked as magnets in early compasses. The Greek

word for amber is electrum, and the association between magnetism and static charges led to our

word “electricity.”

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Page 1 - Micro Drives

Micro Drives Terence O’Kelly From cave walls to stone tablets to papyrus to photographic film to laser devices, storage technology has always come

Page 2 - Magnetic “Printing”

strength required to switch the poles is the crystal’s “coercivity.” Oberlin Smith realized he could draw magnetic patterns in material coated with m

Page 3 - Relative Height of Debris

one way while the other half are magnetized the other way in a completely random way. No pattern exists, and the coating is “blank.” THE INTRODU

Page 4

MICRO DRIVES: TECHNOLOGY GOES TINY Figure 3 is a picture of a micro hard drive. The aerodynamic electromagnetic head lies at the end of a lightweigh

Page 5 - Perpendicular Recording

PERPENDICULAR RECORDING—AN OLD THEORY BECOMES REALITY One solution to the problem of self-erasure has been to align the particles vertically in the

Page 6 - Micro Drive vs. UFD

yield rates improve; but with the leap in density provided by perpendicular recording, micro drives are likely to keep their cost advantage for the re

Page 7

Some new designs actually incorporate “drop sensors” that stop a drive, park the head, and lock the head arm within 140 milliseconds (the amount

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Imation 32601060 Fiche technique

Naviguer en ligne ou télécharger Fiche technique pour Disques durs externes Imation 32601060. Imation Mega TravelDrive 12GB Manuel d'utilisatio

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