[GLLUG] Re: linux-user digest, Vol 1 #932 - 3 msgs

[Bruce Smith]

> > > Some very old CD-ROM drives (circa 1990) won't read CD-Rs at all.
> > > Short of that, I haven't had any trouble.
> >
> > And CD drives much newer than that will not read rewritable media.
> > I've found drives slower than _roughly_ 18X speed won't read CDRW.
> 
> The speed of the drive doesn't matter at all.  It's whether or not the 
> drive has automatic gain control.  Remember that the land/pit 
> reflectivity difference for a CD-R is roughly 85%/15%.  For CD-RWs, 
> it's more like 20%/5%.  Drives with auto gain control will have the 
> "multi-read" logo on them somewhere, and they should be able to read 
> everything.  The really cheap drives will not have auto gain control, 
> since it costs a few $/unit to implement.  Drives made before ~1998 
> won't have it either.

Right, it's just been my experience that drives were around the 16X-18X
speed when the cut over happened.  I use it as a rule of thumb, since
it's usually easier to the tell the drive speed than the date that the
drive was manufactured.  (and the date isn't an exact test either)

  - BS