> Sato and Laurens,
>
> Probally the problem is with CD-ROM file format (ISO9660, Joilet,
> etc...) and not with speed.
It doesn't exactly have to do with speed, but rather with age. Older
CD-readers often don't support CD-R and CD-RW discs, because of several
physical differences, i.e. the reflection of the discs. For an explanation
of that, read my other mail.
> principally because actual CD-ROM drives
> are like old CDs but with a large cache (few time ago I found in
> Brazil a shop selling a 100x CD-ROM. Magic? No! A secondary cache
> stored in local harddisk!).
Ermm... usually CD drives running at 50 speed REALLY run at 50 speed, they
don't use tricks like caching or so...
There is a nasty trick, however. They always find one (and expoit it, just
like the harddisks of which the size is given in millions of bytes instead
of 1048576s of bytes)...
With CD-readers the trick is the following: the center tracks of a CD are
smaller than the outer tracks. However, every track contains as much
information as every other track. So the holes in the inner tracks have less
space between them than the outer tracks. If a drive reads at a certain
speed, the motor has to turn faster for the outer than for the inner tracks.
All CD-drives up to about 4 speed did this, and had a variable rotation
speed. But then the following trick was discovered: why not let it turn at a
constant rate? Then it will read the inner tracks faster than the outer
tracks, but it won't have to use variable speeds.
Well, and since then the drive manufacturers give the speed on the inner
tracks (=the first part of the CD) as the drive speed. But on the outer
tracks it is much slower. So a REAL 4-speed drive is much faster than a
'fake' 4-speed drive.
~Grauw
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