Disks as a Roll Conservation Medium
By Thomas Henden
When reading all the comments regarding media that contains information, one important thing stroke me when I read about the magnetic media, as audio tape or floppy disks.
One should remember that even if the magnetic material on those media could be made to last forever, the magnetic orientation of the atoms in it will not. We' ve all heard that loudspeakers, monitors and other electric equipment have a magnetic field around itself, but seem to forget that the earth itself is a huge magnet. The only safe way to store magnetic media would therefore be in a 'Farady' s cage' which really is what the name says, a cage, if you like it, a bird cage, that is connected to earth. (grounded)
I've heard that in medical science, when measuring the extremely weak magnetic fields of the human brain, they even have two cages, one inside the other, to keep the disturbing magnetic field from earth away.
That means indeed, it is a bit impractical to make a 100% magnetic field-less storage for any magnetic recording, be they disks or tapes.
[ Editor's Note:
[
[ I don't think a field-less storage vault is required for magnetic
[ disks and tape. One of the desirable properties of digital magnetic
[ media is that it has a very peculiar B-H curve. Specifically
[ it takes a very strong applied magnetic field to get the
[ stored magnetic state to change. Once changed, it takes an
[ equally strong opposite applied magnetic field to get the
[ stored magnet state to change back. In particular, the strength
[ of applied field required is much larger than any ambient (earth,
[ etc) magnetic field. Otherwise, these digital medias would be essentially
[ useless. I don't think that the stored magnetic field degrades with
[ time, unless the atoms can physically migrate in the medium (i.e. how
[ rigid is the [ coating on or in the plastic)
[
[ Robbie, Wayne, or others: am I remembering my college courses
[ correctly ?
[
[ Jody
What is a much better options, is already mentioned on this list, by copying all the files on a CD-ROM, but it should not be a CD-ROM of any kind. The usual ones are made in plastic, which guarantees to break down in a period of a number of years. The special CD-ROM used for long-term storage, should be made in a glass material, and according to a friend of mine working in a encyclopedia publisher company, tells that this should be the future, since the expected lifetime of such CD-ROMS is expected to be 2-300 years.
Is there any better suggestions to expand the lifetime of our valuable records further, so our grand-grand-grand-grand children will be able to listen to Grieg himself play at least 1000 years from now? :-)
A question;
Are anyone willing to enclose any programs to the automatic-music-list, so that I and hopefully many other will be able to listen to music-files that sometimes are enclosed with the list? (Either they are on 'punched' MIDI format or anything else!)
Is it possibly that such files, and also the programs can be sent as an attachment to the automatic-music-list, and not in the list. The program we use on my school (Pegasus Mail) seems not to be able to extract files out of the text, (and I am not sure in which TMP-file the current letter is contained). However, Pegasus Mail is fully capable to extract attachments, and save them to a (short term lasting!) disk. :-)
Sincerely Thomas Henden from Norway
Thomas.Henden@stud.hf.hioslo.no
[ Thomas, I will try to learn to encapsulate the files I attach
[ correctly. Can you (or anyone else) tell me: Does Pegasus mail
[ support all standard "MIME" encapsulation formats ?
[
[ Meanwhile, I'll collect up the recent "attachments" and put them
[ in the FTP archive under the "misc" directory:
[
[ ftp://ftp.foxtail.com/pub/automatic-music/misc
[
[ Jody |
(Message sent Fri 8 Mar 1996, 15:14:58 GMT, from time zone GMT+0100.) |
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