Why didn't you just google the info ?
http://www.webopedia.com/DidYouKnow/.../CDBurning.asp
Understanding CD Burner Speeds
Have you ever wondered what all those numbers mean when you go to buy a CD
burner? When you see a configuration that looks like 12x2x24 (three numbers
separated by the letter "x"), these numbers indicate the drive speeds of the
CD drive. The "x" stands for the transfer of 150 KB of data per second, and
each number represents a different action that the CD drive can take. A CD-R
drive has two actions -- recording onto and reading from compact discs. A
CD-RW drive has three actions -- recording, rewriting (erasing and recording
over) and reading. When looking at the drive speeds, the first number ("12"
in the above example) indicates the speed at which the CD drive will record
data onto a CD-R compact disc. So, in the above example, the CD drive will
record data at 12 times 150 KB/second. The second number ("2" in the above
example) indicates the speed at which the CD drive will rewrite data onto a
CD-RW compact disc. So in the above example, the CD drive will rewrite data
onto the compact disc at 2 times 150 KB/second. Typically, the second number,
the rewrite speed, is lower than the first number, the write speed, because
rewriting is a slower process than writing. The last number ("24" in the
above example) indicates the speed at which the drive will read data from a
compact disc. So in the above example, the CD drive will read data from a
compact disc at 24 times 150 KB/second.
CD-R compact discs are discs that can be recorded on only once. Once the
data has been burned, it is permanent and cannot be erased. CD-RW compact
discs are discs that can be recorded, erased and re-recorded over. Most audio
CD players, especially older models, can only read CD-R discs, so it is best
to record music onto CD-Rs. CD-RWs are typically used to store data or used
as back up files.
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Disclaimer: The information has been posted "as is" with no warranties or
guarantees and doesn''t give any rights.
"jacquieleppard" wrote:
> I want to buy a CD burner to download my music. I want to know what LG
> 40x12/40x means. I can buy one from a friend for $10.00. My email,
> Oh, and it's a year old.
> --
> j.l.