Magneto Optical disk

Magneto Optical disk (MOD)

the Magneto Optical disk (MOD) is a rotary storage medium, which is optically selected and described magnetically.

With the Magneto Optical disk does not give it a uniform way of writing. Some call you also Magneto Optical disk (with „C “in disk). Other well-known synonyms of the MOD are mode chain (English. MO-disk) or briefly MO. The latter gives it also in the popular variants to mol on work and MO-medium (and/or. more rarely) MO-cartridge.

Table of contents

history and variants

  • 1992: MD (mini disk) by Sony, Speicherkapazität: At the beginning of 140 MT, later 1 GB (rear-MD). The mini disk is a most well-known MOD representative and primarily for mobile Musikplayer and in radio stations was used.

magnetooptic technology

before the letter is additionally an erasing process necessary, which is realized over the Curie point by heating up. Subsequently, with a laser the disk is heated up on the mentioned temperature, so that it can be magnetized accordingly. This again is done via polarizing the laser beam. The whole is read either with a weak laser or with electromagnets, depending on like the data medium is constituted.

specification of the media

the knowledge about the specification of the data medium is useful during the evaluation of the MO-technology and with the purchase of liking advice and - media. In the following only the information is represented, which is from direct, general interest. Purely technical details are evident in the sources, see chapters standards and standards.

  • Appearance: The MO-media are durably in a sleeve, which resembles 3.5 a " disk, accommodated, therefore also the name MO disk. This sleeve is called also cartridge. 3.5 " MO-medium is approximately twice as thick like 3.5 " a disk.
  • Diameter: There are the MO-media in two different diameters: 90 mm (to that " crest factor corresponds to 3.5) and 130 mm (that 5.25 " format corresponds to that).
  • Storage capacity: The storage capacity of the MO-media depends on the diameter, the track density, the bit density and the sector size. The following capacities are usual, whereby the smaller in each case only drive assemblies older for support are still available:
Diameter sector size storage capacity
3.5 " 512 byte 128 MT (megabyte), 230 MT, 540 MT
3.5 " 2,048 byte 640 MT, 1,300 MT and 2,300 MT
5.25 " 512 byte 650 MT to 4,100 MT
5.25 " 1,024 byte 650 MT to 4,800 MT
5.25 " 2,048 byte 5,200 MT to 13,700 MT

of differences of the MO to a DVD-RAM

an opened MOD, from which their sectoring is recognizable in many small scattered rectangles expresses itself (see also enlargement).
A DVD-RAM possesses same sectoring as the MOD.

In the literature and practice the MO is often compared with the DVD-RAM. Both storage media point the community of sectoring to (see. Illustrations), but otherwise have them due to their different photograph procedures not much together. Briefly said, a MO notes the data magnetically, a DVD-RAM optically.

Apart from these principle-conditioned differences still further is added during the storage capacity, the medium prices, the transfer service as well as the spreading. Current 3.5 a " MO-disk brings it on maximally 2.3 GB, a DVD-RAM to 4,7 GB. One concerning the price spends 2.3 GB on a MO-disk well 20 euro, on 4.7 GB DVD-RAM a medium about 6 euro. The transfer service of DVD-RAM - is superior to drive assemblies from mol on works. One finds MO-systems rather within professional IT-ranges, while a DVD-RAM - burner nowadays for everyone is affordable. The MOD is recognized of newer operating systems than non removable disk, while the DVD-RAM is merged partly than DVD burners. From this the following handling differences result:

  • The MOD is natively supported, since she behaves like a change non removable disk, by many operating systems. A DVD-RAM burner is recognized usually as usual DVD burners and installed, to this can be described afterwards with a any pack Writing - software. Additionally one can address a DVD-RAM burner in addition, via a DVD-RAM device driver as removable data carriers. (Note: This kind of the removable data carrier integration differs the partly substantially under different operating systems as well as Windows - versions, besides the same adjustment possibilities as with do not exist a MOD Wechselfestplatte.)

MOD possesses a higher physical data security opposite the DVD-RAM, because:

  • MO-media are perfectly light insensitive,
  • MO-media to approx. 100 °C is temperature insensitive,
  • MO-media to approx. 100 °C opposite magnetic fields is insensitive,
  • current MO-media is surrounded by a protecting plastic covering always (similarly 3.5 " disks - only more stable). DVD-RAM - Media against it (depending upon used burner) ever more frequently without protecting cartridge to be used must, which the danger of damages (e.g. Scratch) with the use increases.
  • MO-media always over a mechanical write lockout switch order, which prevents the deletion reliably by faulty operation or by incorrect software.

standards and standard

  • ISO/CInternational Electronical Commission 10090 - defines MO-media of 90 mm in diameter with 128 MT storage capacity.
  • ISO/CInternational Electronical Commission 13963 - Defined MO-media of 90 mm in diameter with 230 MT storage capacity.
  • ISO/CInternational Electronical Commission 15041 - Defined MO-media of 90 mm in diameter with 540 MT and 640 MT storage capacity.
  • ISO/CInternational Electronical Commission 15286 - Defined MO-media of 130 mm in diameter with 5,2 GB storage capacity.
  • ISO/CInternational Electronical Commission 22092 - Defined MO-media of 130 mm in diameter with 9,1 GB storage capacity (is based on the ECMA-322).


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Commons: MO - Pictures, videos and/or audio files

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