From: Benjamin Koh (benkoh_at_stanford.edu)
Date: Sat Nov 03 2001 - 15:18:51 EST
"James H. E. Maugham" wrote:
>
> I'm pretty sure that the CD drives are CLV. IIRC you could hear it speed shift
> as the heads moved from the inner to the outer tracks. I'll admit though that I
> haven't had any CD drives in my machines in a long time, just the DVD drives, so
> my recollection could be fuzzy.
>
> It _might_ be CAV. The spec sheet for the 24X drive from Toshiba states the
> rotational speed is 5400RPM:
> http://www.toshiba.com/taecdpd/techdocs/1902B/1902spec.shtml, but if that were
> the case they would run at a constant speed which would never change regardless
> of head position. I'm working on an admittedly faulty memory here, but I seem to
> recall the 24X drive doing a lot of speed shifting when installing software.
Many recently-built drives use a mixture of CAV and CLV. Usually the
disc is divided into different speed zones within which different CAV or
CLV speeds are used. As the drive seeks to different spots on the disc
the motor spindle speeds up or slows down appropriately to the
rotational speed (CAV) or range of rotational speeds (CLV) designated
for that region. My CDROM drive's braking is very audible - it appears
to simply use a piece of plastic to press against the disc's outer edge
to slow it down.
Benjamin
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