In comp.sys.ibm.pc.hardware.misc
wrote:
> We know that floppies written by one machine can be difficult to
> read by a different machine, because of expected mechanical
> differences between the machines.
> So also the tolerance/settings of diffeent CDreaders is expected
> to give similar problems
Not really. The mechanisms are completely different. For once,
floppies are read magnetically with a coil in physical contact,
whuile CD/DVD are read with a laser. Floppies have stepper morors
and cannot do fine-control, while CD/DVD both has it and needs
it to work in the first place as the tracks are too fine and
the rotation is too imprecise.
> I normally don't use CDs, so I've just got 2 scrap CDreaders
> which I plugin if I need to read a CD, which I've tried now
> that a friend has posted 2 CD from the other side of the planet.
> I've noticed that the one reader works well with old RH6.2
> linux but not with later versions.
What interface? What kernel? What does "works not well" mean?
> Also since I need to boot from the 1 CD I have to use the BIOS.
> And since both my machines show differing 'errors', it suggests
> that a marginal mechanical setting exists.
Very unlikely. It can however be a marginal optical situation,
which typically is created by marginal disks or, more rearely,
dust in the drives. Also very old drives can have laser degradation
if used long enough or indead mechanical failure in the focussing
and adjustment mechanism.
> Do CDreaders auto adjust, so that the mechanics of different
> readers is equaled out ?
Yes.
Arno
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