[ale] OT: CD drive and revolution speed correlation?

[Jeff Hubbs]

*Audio CDs* practice Constant Tangential Velocity in playback.  For
data CDs, it's more arbitrary; my understanding was that a "52x"
CD-ROM drive is only 52x at or near the outer edge, where the drive's
maximum rotational speed corresponds to the highest data rate.  It's
reasonable to say that CDs of all sorts have a constant tangential
data density independent of radius.

I recall that we've at least one person on the list who has had a CD
shatter under load inside a drive.  I have had a CD *eject* at speed
once.  I ran.

On Wed, Mar 4, 2009 at 9:47 AM, Devnull <devnull at iamdevnull.info> wrote:
> On Wed, Mar 4, 2009 at 09:35, Jim Kinney <jim.kinney at gmail.com> wrote:
>> I'm pretty sure the rotational speed for any given value is not fixed
>> but variable based on head location. If speed is fixed, bit rate
>> increases with increased distance from spindle. I would expect the
>> data rate to have a factor of pi in it somewhere since it relates to
>> radius and circumference.
>>
>
> Please, correct me if I am wrong, but I thought that CDs are written
> with CLV (Constant Linear Velocity), so that the drive modulates the
> CD revolution speed in such a way that data passes over the head at an
> equal frequency. [1] When I use the eject command, I am changing the
> high level speed (i.e. 1x, 2x, 3x, 4x), and not the RPM speed. If you
> want, I can provide you with a copy of my data.
>
> [1] http://everything2.com/e2node/Constant%2520Linear%2520Velocity
> --
> -
> /dev/null
> We are the Pentium of Borg. Division is futile. You will be approximated.
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