Future of CDROM, DVD, etc.

Richard Zander rzander at SCIENCEBUFF.ORG
Mon May 1 09:59:05 CDT 2000

PC Magazine recently has discussed compatibility problems with CDs. 2000
Apr. 4 issue, p. 103: ""CD-RW's ... often cannot be read on even fairly
recently manufactured CD drives. The problem lies in the nature of CD-R and
CD-RW disks, which use a dye layer for storing information, rather than the
"pits and flats" method of recording data in factory-produced CDs.... both
CD-Rs and CD-RWs reflect less light than conventionally produced
CDs...making them hard to read. Result: CD-Rs can be read by most CD drives
but not by DVD drives. CD-RWs can be read by most DVD drives but not
universally on CD drives, especially not on those built more than a year

And... PC Magazine Mar. 21, page 183: "A DVD-RAM drive can read almost any
CD disk, though some drives may have problems with some times of CD-R media.
DVD-RAM disks won't transfer to other types of drives as well as CD-RW;
DVD-RAM drives can't write to CD-R or CD-RW media, and most DVD-ROM drives
can't read DVD-RAM disks."

I think problems with operating systems (my PC can read MAC formatted CDs
using ARDI virtual Macintosh software, but can future systems do the same?)
and degradation of particular media (hard disks, floppies, CDs) mean that we
should (1) expect to transfer publications from media to media as technology
changes, and (2) eschew using operating-system-specific programs to present
data (e.g. type "install" at D: prompt). The absolute minimum expectation
for continued long-term support from libraries for storing and making
readable publications is ASCII, Unicode, HTML 4.0, and .PDF formats, and
many graphics formats. Anything more than this (at the present time) is
wishful thinking.

Example: Flora Online was established in 1987 as an electronic journal for
botanical research. It is archived through the courtesy of U. Kansas :
Some of the articles are in plain ASCII text. They should be readable in
1000 years as the journal is (I hope) transferred to different media. Some
of the articles are in Zip format, and some are of programs that require MS
Dos to run; I don't expect any easy of access for these, but at least they
will probably be around to amuse experts in ancient languages.

Richard H. Zander
Curator of Botany
Buffalo Museum of Science
1020 Humboldt Pkwy
Buffalo, NY 14211 USA
email: rzander at sciencebuff.org
voice: 716-895-5200 x 351

----- Original Message -----
From: "Guy Nesom" <guynesom at INTREX.NET>
Sent: Sunday, April 30, 2000 2:10 PM
Subject: Re: Future of CDROM, DVD, etc.

> A neighbor here who is in the business of manufacturing CDs says that
> read-only discs, made after ca 1990, have an expected life of about 100
> based on estimates from various kinds of tests.  Those that can be written
> only once, as well as those that are "rewritable," have a life expectancy
> about 50 years.
> Guy Nesom
> Chapel Hill, NC
> Kenelm Philip wrote:
> > > But it kind of makes you wonder if there could be some unknown defect
> > > today's CDROM's which might cause an escalating loss of electronic
> > > over time
> >
> > There are a number of _known_ defects that have turned up in some
> > of music CDs, which eventually result in total loss of signal. The two
> > major types are 'bronze corrosion', and 'milky clouding'. Both types
> > take a number of years to destroy the readability of the discs. These
> > defects (so far) have affected only a small proportion of the total
> > production of CDs--but they should serve as a warning that CDs are not
> > necessarily reliable longterm data storage media in all cases.
> >
> >                                                         Ken Philip
> > fnkwp at uaf.edu

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