While the mentioned site does claim that the /U switch overwrites the drive,
this is not correct.  Originally, /U (unconditional) formatting meant that
the old version 5 and version 6 dos command 'unformat' would not work to
recover the drive.  As 'unformat' is no longer supported in version 7 of
dos, the command is redundant, all formats are now unconditional.  I am not
too familiar with the process, but I think an unconditional format in dos
version 6 prevented format from writing a block of data that the unformat
command could then use to perform its magic.  I think format /u also
overwrote cetain directory structures on the drive, making a FILE SYSTEM
recovery problematic.  However, the data area of the drive was intact and
could be read, only the beginning and end markers for the files were lost.
Regardless of how accurately I recall the details, format /u will not
securely overwrite a drive.
Tom Turak

-----Original Message-----
From: Dave Ralph [mailto:[log in to unmask]]
Sent: Thursday, April 25, 2002 4:34 PM

2.  For all but NSA decrypters who would do magnetic magic to see what is
under a re-write of the disk media, one can do a "simple" format of the
drive with the following command from a "DOS" prompt but with the added
switch which overwrites the drive with blank spaces, and has the added
benefit that it is free with Windows.

FORMAT C: /U   or   FORMAT C: /U/S

/U parameter performs an UNCONDITIONAL format, which DESTROYS every byte of
data on a disk by overwriting it
with with blank spaces

/U/S adds the System Files on completion

(Taken from the following link)

http://www.powerload.fsnet.co.uk/harddisk.htm

Dave Ralph
> >I want to give away one of my computers but it has some sensitive data
> on it.  To make sure it cannot be recovered, is it enough to format the
> hard drives or do I need to use some sort of disk eraser program?
> >
> >Marilyn

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