Larry, John, John, Sharon, et al,
Larry basically captured the recording process ("exciting the surface"
notwithstanding ;) ) - I would clarify that most manufactured discs today
are not burned, but rather pressed or stamped to create the pits & grooves.
For CD-R media, the information is stored in a dye substrate, the
reflectance of which is changed by the laster to produce light & dark spots
(1s and 0s). For CD-RW and most DVD technologies, the recording substrate is
in a crystalline state which changes properties to an amorphous state when
the laser hits it. Some substrates can only change once (DVD+R, DVD-R, etc.)
which others can be changed repeatedly (DVD+RW, CD-RW, etc.).
Magneto-optical works by heating the recording substrate to the point at
which its magnetic properties change and then encoding the 1 or 0
appropriately.
This is all part of the hopefully soon to be released AIIM TR-41 technical
report on "Optical Disk Storage, Management, and Technology".
Cheers,
Jesse Wilkins
CDIA+, LIT, EDP, ICP
IMERGE Consulting
(303) 574-1455 office
(303) 484-4142 fax
[log in to unmask]
http://www.imergeconsult.com
>From: "Gervais, John" <[log in to unmask]>
>Reply-To: Records Management Program <[log in to unmask]>
>To: [log in to unmask]
>Subject: CD Permanence
>Date: Wed, 22 Dec 2004 14:14:35 -0500
>
>Larry's post:...."an electrical charge being placed across the media that
>"excites" the surface and either turns on or off..."
>I just love it when people use eclectic terminology when explaining
>something! Well said Larry. Call me weird but that is what makes our
>somewhat dreary IM topics interesting!
>
>Now a question - What side of the CD is the information burned on? The
>side
>with the words or the other side? I have heard people say different
>things?
>I have also heard that if you have scratches that the CD can be fixed? If
>this works, does it have an effect on its permanence? Thanks
>
>John A. Gervais
>Program Manager
>Policy and Standards Section
>Information Policy and Governance Division
>Intergovernmental and International Affairs Directorate
>Policy and Planning Branch
>Canada Revenue Agency
>25 Nicolas Street, 16th Floor
>Ottawa, Ontario, Canada, K1A 0L5
>
>' 1-613-688-9302
>* mailto:[log in to unmask]
>" http://www.cra-arc.gc.ca/
>
>List archives at http://lists.ufl.edu/archives/recmgmt-l.html
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