11 Aug
2004
11 Aug
'04
7:32 a.m.
On Wed, 11 Aug 2004, Dwight K. Elvey wrote:
One thing that could be done but I'm sure many
will think
I'm crazy. If the files contained OpenBoot source code to describe
the data, one can then create almost anything one wants.
I'm not familiar with OpenBoot. Can you explain this a bit more?
We need to remember that what normally comes out of a
floppy
controller chip is not the actual data on the disk. The information
on the disk is a more complex. It contains things like special
marks for indexing, headers and even errors. These need to
be represented as well. We need to be looking at capturing the
raw data from the disk. And at methods of post processing this
to a form similar to what comes from the floppy controller.
There are multiple levels at which someone may want to archive a medium.
There's the physical level, as you describe above. Then there's the level
in between physical and logical, which is, to use the example of floppy
disks again, tracks and sectors. And then there's the logical level which
is an actual filesystem with a directory and filenames, etc.
This spec should be designed to be able to handle all three types
simultaneously within the same image file.
What I mean is that it might be useful to have (to use a floppy disk as an
example again) most of the disk encoded in a track/sector representation,
but then have one particular track encoded at a bit level, because perhaps
it contains special signatures that are part of a copy protection scheme.
If the image is ever used to re-create the original physical disk, the
binary data will be essential if the disk is going to actually be expected
to work (unless the copy protection scheme is removed at that point).
--
Sellam Ismail Vintage Computer Festival
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