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Re: "Digital Dark Age"



> changes have been made to the data. A CD-ROM will never stop working. It has
> no wear out or failure mechanisms. The only thing needed to read the CD-ROM is

A CD-ROM's failure mechanism is oxidation. The reflective surface is
aluminum, which will oxidize, rendering it non-reflective, and therefore
unreadable (even with the built-in error correction codes) The surface
is normally sealed against this, but there is no long-term knowledge of
how good that seal is. (And, there is a lot of anecdotal evidence that
it breaks down after 10-15 years, allows some oxygen in.) Also,
recordable CDs use an organic dye to create the pits on the surface --
all dyes, with time, break down. Currently, it's said to be 20-30 years,
but again, no one knows, with a lot of anecdotal evidence that it could
be as short as 6-9 months depending on the batch.

> a CD-ROM reader (100's of millions built and 100's millions more to be built)
> and a PC.  Under what senario is our culture going to be at the point that
> anyone interested can no longer make or aquire a simple PC with a CD-ROM
> reader. The shear numbers of PC's manufactured insures that they will be
> available in the distant future to view information carefully stored on CD-

But the real issue is not media migration. Media migration is a pretty
well understood process at this point, basically involving setting up a
process to ensure that the media is migrated at the appropriate point.
(It also helps that media tends to increase in size in order of
magnitude jumps) The major cases where media migration has been an issue
has been instances where there was _no_ plan at all to migrate media,
until it was too late.

The issue is content migration: what happens when the software isn't
around anymore, doesn't run anymore, and no one knows the disk format. I
know I have a lot of stuff I wrote in WordStar (admittedly, it was in
elementary school), that can't be read anymore -- no major word
processor can import WordStar 3.3 anymore. (And yes, at one point,
everyone used WordStar 3.3. It was the industry standard for about 4
years) It's a hard problem, especially since content conversion is
rarely 100% -- you loose little things, things don't match up perfectly.
At what point is too much loss unacceptable (and what do you do about
it?) Of course, paper/microfilm is also unacceptable in many cases. What
is a paper version of an interactive multimedia presentation?

It's a hard problem. I spent two years working on a research team
dealing with issues of electronic records preservation, and it's got no
easy answers. Saying "well, PDF & CD-ROMS will always be around"
invariably does not address all the problems (and some very good people
have said this)

MJH

--
Mark    -- http://www-personal.si.umich.edu/~handel
Handel  -- handel@umich.edu
        -- 805 Spring St. #2, Ann Arbor, MI 48103
        -- +1 734 669-0311


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