Re: [TCLUG:20847] Very stupid CD Burning Question:

[Philip C Mendelsohn <mend0070@tc.umn.edu>]

On Wed, 30 Aug 2000, saber wrote:

> I used to try to stay in the 630-640 meg range and I *would* end up with
> coasters if I tried to do 650 megs. A friend had similar problems. More
> modern cd-writers (his was '96, mine was '98?) may be more forgiving.

OK -- that proves my point exactly!  Sorry that you had to trim it down.

> I always wondered if the ISO9660 filesystem was figured in as overhead.

I don't know exactly what you mean by figured in, but absolutely.  If you
look at the raw number of pits made in a CD-ROM or CD-R or CD-RW, the
amount of data that *could* be stored is about 2.4 GigaBytes.  Of course,
you'd never get that -- the error rates would render it useless.

In essence, each bit is written 3 or 4 times, and that is sufficient to be
sure that at least *one* of the copies will read correctly.

[That's a mind numbing simplification of the error concealment and
correction involved, but the ratio is about right.]

I can cite references if anyone is interested in a little light reading on
optical storage systems -- just e-mail me.

Cheers,
Phil

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