My classiccmp non-retirement :-)

Antonio Carlini a.carlini at
Mon Jun 20 05:48:13 CDT 2005

>I would appreciate a recommendation!  How long should
>a CD be replied upon? 

You cannot rely on a CD (not even a pressed CD) for
anything important. You need at least two CDs, preferably
more. By the time you realise you were unlucky enough
to hit the bad one in the batch, it is too late.

I've had a few CD-Rs die and two DVD-Rs die. For stuff I
care about, I burn to CD-R twice. I expect to take the
whole lot and reburn to something else eventually. I
keep waiting for the C3D or similar technology to surface
(say 100GB per disc) but I'm still waiting. Given the
drop in £/GB of had drives lately, I may well put everything
onto a spare drive in the meantime.

> If the image file for the CD
> is retained, how long before it will not be possible
> to burn a new CD and use it on what will then be a
> current operating system?

The ISO ormat is well documented. If you ignore various
copy-protections schemes, the for straight-forward normal
CDs, I would be surprised if you cannot access one 100
years from now. You almost certainly won't be able to burn
a new CD-R (since noone wil be making the media) but you
will be able to access an ISO file. If you use something
like Nero with its (I assume ...) undocumented .NRG format,
you'll have to spin up an emulator and a copy of WXP with
Nero. Convert to ISO before then and you should be OK.

I'd be surprised if noone has a working DVD drive 50
years from now. Even the next generation stuff (HD-DVD)
sounds like it will be able to read CDs.

>stating when the CD will no longer be readable is almost
>a pure guess, but I was wondering is anyone is willing
>to suggest if it will be less than 3 decades or more
>than 10 decades?

Surely reading ISO9660 image files will be possible essentially
forever, unless we lose the standard (or the ability to program)!
Being able to read the media may prove difficult beyond 100 years
or so. As long as the current equivalent to CDROM remains based on
rotating media that is read optically, modifying such a drive to
read a CDROM will remain feasible. Once we move to something as
different to CDROM as those are to floppy disk drives, then we
will get to find out how hard it is to build a drive from scratch!

Has anyone built a floppy drive from scratch? Without salvaging
any mechanical parts or heads from an existing floppy? I'm
assuming that electronic processing is not a problem (in
principle) for either floppy disks or CDROMs/DVDROMs.


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