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Date: Mon, 23 Jul 2012 03:10:40 -0700
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Cc: freebsd-questions@freebsd.org
Subject: Re: fsck on FAT32 filesystem?
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Robert Bonomi <bonomi@mail.r-bonomi.com> wrote:

> MSDOS/PCDOS had -no- O/S functions to directly access actual disk
> devices.  The ONLY fuctionality provided to the user, by the "O/S"
> was filesystem based access.  To get 'raw' device access, one had 
> to bypass the O/S entirely, and use direct BIOS calls (INT 13h).

FALSE TO FACT.

MSDOS/PCDOS had no _documented_ functions to directly access the
disks, bypassing the file system, but the functions _did_ exist.
The debugger's "read sector" and "write sector" commands used them,
and I suspect chkdsk, scandisk, and format probably also used them
although I never had occasion to verify one way or the other.