On Wed, 19 Aug 2009 15:22:08 -0700 (PDT), Joshua Snodgrass
wrote:
: On Aug 2, 6:44*pm, David Nebenzahl wrote:
: On 8/2/2009 5:58 AM Robert Coe spake thus:
:
: If you want to irretrievably destroy the data on a CD, scrape the
: coating off of the "back" side; that's where the information is. The
: reader looks through a layer of clear plastic, which effectively
: protects the data from damage to the front side. That's why scratches
: on the front side usually don't have much of an effect. And why users
: *should be more careful not to damage the back side than they usually
: are.
:
: Or so I've been told by those who know more about CDs than I do.
:
: Take it from someone who used to work with CDs; you've got it pretty
: much correct.
:
: Actually, you don't even need to scratch off much of the coating to make
: a CD unreadable and the data unrecoverable; a few well-placed scratches,
: especially concentric with the disc, will do the job. That's because
: you're destroying most of the data in each track. (This is why users are
: advised to clean CDs only by wiping radially--from the center of the
: disc towards the edge--rather than circularly; any damage done this way
: will be distributed over different tracks, which reduces the risk of
: unrecoverable read errors.)
:
: BTW, I'm not sure that DVDs work entirely the same way.
:
: Basically the same way, though as someone else pointed out, DVDs have
: multiple layers. Still read from the "bottom" of the disc.
:
: --
: Found--the gene that causes belief in genetic determinism
:
: Just so everyone knows, Julie Snodgrass was my mother. Joe Snodgrass
: is my father. I am their son. If you guys want real answers about
: this feel free to ask me. . My name is Joshua
: Snodgrass.

No offense intended, but is that factoid germane to this discussion in some
way? This isn't a genealogy newsgroup.

Bob