Reading CD-RWs in a CD-ROM Drive

I've got a Linux box running the SuSE 9 distro.  Today I was looking
to read the contents of a CD-RW in the CD-ROM drive (the Linux box
doesn't have a CD writer), and KDE came back with an error that no
media was found.  Is there some software that I need to run to allow
this?

Thanks.
Bill Lugg

There's no special software needed.  It should "just work" on any
reasonably new CD-ROM drive.  However, some *really* old CD-ROM drives
(typically 4X and slower drives) physically cannot read CD-RW media.

On 29 Jan 2004 10:13:31 -0800, William Lugg staggered into the Black Sun
and said:

CD-RWs are not always readable in a non-CD-RW drive for reasons that
have *nothing* to do with software.

A CD-ROM or CD-R has lands that reflect ~90% of light and pits that
reflect ~10% of light.  CD-RWs, OTOH, have lands that reflect ~30% of
light and pits that reflect ~5% of light.  Modern CD-R* and DVD+-R*
drives typically have something called "automatic gain control" that
compensates for the differing reflectivity of CD-RW media.  Really old
CD-R* devices don't have this, so they see the CD-RW as one big pit,
meaning it's unreadable.  Some cheaply made new CD-R* devices don't have
auto gain control because that adds $1-2 to the manufacturing cost.

I know this isn't what you wanted to hear, but hey, low-speed CD-RW IDE
drives are cheaper than ever.  Plonk down $50 or so for one if you
anticipate needing to read CD-RW media or burn CDs.  HTH,

-- 
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
Brainbench MVP for Linux Admin /    mail: TRAP + SPAN don't belong
 http://www.**--****.com/      /                Hire me! 
-----------------------------/  http://www.**--****.com/ ~mhgraham/resume

In message 
< XXXX@XXXXX.COM >, 
Dances With Crows < XXXX@XXXXX.COM > writes
Just to add to the confusion, I have a DVD drive which doesn't read some 
CD-Rs.
-- 
Joe

On Fri, 30 Jan 2004 18:42:42 +0000, Joe staggered into the Black Sun and
said:

(explanation off-the-cuff and half-remembered; corrections welcome.)

This is because CD-ROMs use an infrared laser (780nm) while DVD-ROMs use
a red laser (~650nm).  CD-R dyes are, of course, set for maximum
performance at the infrared wavelength and may fall off drastically at
higher wavelengths.  CD-ROMs may reflect reasonably well at higher
wavelengths because there's metal there, not just dye.  Some DVD-ROM
units may only have a red laser; more expensive DVD-ROM and all
DVD+-R(W) devices that can also write CD-R(W)s should have a dedicated
infrared laser so all CD-R media should be readable.

-- 
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
Brainbench MVP for Linux Admin /    mail: TRAP + SPAN don't belong
 http://www.**--****.com/      /                Hire me! 
-----------------------------/  http://www.**--****.com/ ~mhgraham/resume