MSGID: 3:640/1042 8fbe494f
@REPLY: 2:400/567 40370d56
@TZUTC: 1000

Hi Joe.

21-Feb-04 09:45:50, Viktor Pilpenok wrote to Joe Nicholson

 JB>>> CD cross-section   (not to scale)

 JB>>>     "label side"  or "top"
 JB>>> ---------------------  thin plastic
 JB>>> ********************** data layer
 JB>>> ---------------------
 JB>>> |                     |
 JB>>> |                     | thick plastic
 JB>>> |                     |
 JB>>> |                     |
 JB>>> -----------------------
 JB>>>       "data side" or "underside"

 JN>>  You're saying there is data on both sides of a CD?

no the data is recorded in a layer near the label side of the CD but
accessed from the underside.

damage to the label side (like pinholes or scratches) will destroy data,
small scratches to the underside have less effect and can in some cases be
repaired.

 JN>>  Including the back side which rests on the bottom of the cases
 JN>>  and which most everyone grabs to remove a CD from the case?

I grab the disc by the edges, or by the hole and one edge.
fingerprints on the underside can cause reading problems

 JN>>  Are there 2 beams?  One to read each side at the same time?
 JN>>  (Learn something new everyday!)  

One beam from below looks theough the thick plastic to read the data which
is recorded immediately below the label.

Writing on the label side with a hard implement can damage the data layer.

 -=> Bye <=-

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