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Re: What is the dd command ???

Andrew Sackville-West wrote:
On Wed, May 03, 2006 at 10:24:00AM -0500, Mike McCarty wrote:

Andrew Sackville-West wrote:


bootable floppy disk with it. This is different than a windows/dos
made bootable floppy in that it doesn't have any windows or dos system
on it. You use any blank floppy and the rawrite program to copy the
disk image over to the floppy. make sense?

I believe that the disc must have been formatted. Unless a low-level
format has been done to establish sectors, I don't think dd could
write to the floppy. It must also have a BR with a BPB in it, I do
believe, else how could it distinguish, e.g. 720K floppy from a 1.44M
floppy? If I can find a floppy I am willing to degauss, I'll give it
a try...

not to argue :) but the debian installer manual chapter 4.3 makes no

I'm not, either. But the floppy drive has to be told whether
to use high-coercion or low-coercion current drive. Using high-mu
drive on a low-mu disc will likely ruin it. And how can the driver
know what kind of disc is in there?

reference to formatting the floppy. It does refer to make a "sector
copy" and writing in a raw format which tells me its bit-for-bit copy
of a disk including its boot sectors and fs. man dd is suitably

No, a sector copy is not a bit-for-bit copy, as sectors do not have
to be arranged sequentially on the track. In fact, sectors used
normally to be written with interleave to speed up access. I haven't
looked into it lately, so I dunno whether sectors are now commonly
written with interleave of 3 as used to be, or are now sequential.

I can't honestly say what condition the last set of floppies I dd'ed
were, but I do know they wouldn't boot before and would boot after...

I don't believe that the controller can write to the disc
unless the sectors are already laid down, else it wouldn't
know where they were. All discs today are soft sectored.
Until they are formatted, there are no sectors to write, just
blank medium.

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