CD data recovery?

[James Knott]

Lennart Sorensen wrote:
> On Tue, Sep 21, 2004 at 06:45:37AM -0400, James Knott wrote:
> 
>>And, due to CD layout, only full disks will ever use that 50X space, 
>>though you could always pad the disk, so that the data is at the outside.
> 
> 
> I believe dreamcast games took advantage of that and padded out their
> games so the data was as far out on the disk as possible (they were also
> modified CD format holding about 1GB, but same layout otherwise).
> 
> 
>>Incidentally, I believe you mean linear rate, not rotational.  If 
>>rotational, the outer tracks would be spinning faster or slower (RPMs) 
>>than the inner tracks.  That would definitely cause the disks to 
>>fracture, no matter how fast they were spinning.  ;-)
> 
> 
> Well the read speed is a function of where on the disk the head is
> pointing and how fast the disc is rotating.  Since the data is stored at
> a constant bits per distance of track, there is more data on one
> revolution on the outside than the inside, hence at a constant rpm you
> get higher read speeds at the outside than the inside.  original CD
> drives up to around 8x were constant linear speed, so they changed
> rotation speed as they went along to keep a constant read speed, while
> new drives use constant rotation speeds instead and have varying read
> speeds as a result.
> 
> As far as I remember my 52x CD writer will only read pressed CDs at up
> to 40 or 48x (probably 40x) to avoid damaging them, while cd-r it will
> run at 52x.  Supposedly they are more durable than pressed discs.  The
> drive is also supposed to have a reinforced front bezel, just in case :)
> I don't want to know what the inside of the drive would look like if it
> ever had a need to using that reinforcement.

I'm aware of anglular velocity vs linear velocity.  My comments were 
simply a poor attempt at humour, regarding inner and outer tracks having 
different angular or rotational velocity at the same time.  ;-)

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