World's Crappiest Drives (was Re: A&J Microdrive)

From: Michael Nadeau <menadeau_at_mediaone.net>
Date: Thu Dec 7 09:16:57 2000

The top layer--where the label is silkscreened--is not plastic, but a
30-micron layer of lacquer. It doesn't take much to scratch through it. The
plastic layer, through which the laser reads the disc, is 1.2 mm. The
reflective layer, which in most CDs is the aluminum recording surface, is
only a few angstroms thick. It's easy to see why the average CD is such a
fragile storage medium. The best way to avoid scratching CDs is to store
them in their cases and never put any weight on them (like leaving books on
top of them).

BTW, never write on a CD with a felt-tip pen or magic marker. The ink can
easily seep through and affect the laser's ability to read the data. Labels
are a bad idea, too, as they will cause the disc to spin out of balance.

I believe that glass and gold discs are available for archival purposes with
guarantees of holding data for 100 years.

Michael Nadeau
author, The BYTE Guide to CD-ROM


----- Original Message -----
From: "John Foust" <jfoust_at_threedee.com>
To: <classiccmp_at_classiccmp.org>
Sent: Thursday, December 07, 2000 9:22 AM
Subject: Re: World's Crappiest Drives (was Re: A&J Microdrive)


> At 01:49 PM 12/6/00 -0600, Chuck wrote:
> >At 03:29 PM 12/6/2000 -0600, John Foust wrote:
> >>And the technical difference between silver and gold crap? :-)
> >>Different dyes?
> >
> >No, different elements. One uses aluminum foil and the other gold foil.
Aluminum has the unfortunate tendency to oxidize once oxygen permeates(sp?)
the plastic or the top seal. This oxidation shows up as "black crud" growing
from a crack or scratch.
>
> Hmm. And how much plastic has to be scratched off before the foil is
> exposed, and how wide of a scratch on either Al or Au will blow
> away data, given the ECC? If a CD gets scratched, oxidation
> won't happen for a while. Will I notice the scratch before
> it's too late? Am I mistreating archival CDs in the first place?
>
> - John
>
>
Received on Thu Dec 07 2000 - 09:16:57 GMT