-=> Quoting AARON JORDAN to RICK COLLINS <=-
-=> FidoMail to 1:163/215, please.-=<
-> If one did what was suggested, you would _not_ "delete
-> everything on the disk", and, more to the point, you may not
-> fix the virus infection at all. 
-> Those two statements are both correct, and the reson they are
-> correct is related. Can you tell me why? 
AJ> But when you format a disk you do lose all information on that
AJ> disk. It even tells you so. 
Do you?  If you have two partitions on a single disk (C: and D:), do
you lose any data from C: if you format D:?
So what _really_ is the DOS FORMAT command telling you?
AJ> And as to the reputation thing, I don't want to hurt anyone's 
AJ> feelings. I'm just interested and I like to state my point. 
AJ> Feel free to correct if wrong! :) 
No problem.
DOS deals with "logical" drives, so Drive C: in DOS is really
"logical" drive C:, which is only a portion of the "physical" drive -
the real hardware.  So when format tells you "all data will be lost"
it means on the "logical" drive that it is formatting.  If you have
more than one partition, the _other_ partitions are unaffected.
That leads to the next point:  If you have two partitions (C: and
D:), and you FORMAT D:, you can still boot from that drive.  For two
reasons:  first, you didn't delete any data from Drive C: (as
explained above), and _second_ - you didn't touch the Master Boot
Record (MBR) on the disk _or_ the Partition Table (PT).  If you had,
you _couldn't_ boot from the drive, or even get a directory of the
untouched "Drive C:".
So that's the second point:  FORMAT _doesn't_ affect any part of the
disk that isn't part of the "logical" disk structure, and most
particularly it doesn't affect the MBR.
Now, "boot sector viruses" reside in the first sector of the disk -
the MBR.  So FORMAT, _because_ it doesn't affect the MBR or PT,
_cannot_ remove a boot infector.  So, if you FORMAT a disk that has a
boot sector infection, the disk will _still_ be infected, even after
the FORMAT.
All the above is correct for a hard drive:  floppies are a different
story, and FORMAT will destroy all viruses on a floppy.
TTFN. Rick.
Ottawa, ON 19 Jun 18:36 
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