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Date:      Thu, 26 Oct 1995 15:31:43 +1000
From:      Bruce Evans <bde@zeta.org.au>
To:        msmith@atrad.adelaide.edu.au, terry@lambert.org
Cc:        hackers@FreeBSD.org, lenzi@cwbone.bsi.com.br
Subject:   Re: boot disk....
Message-ID:  <199510260531.PAA08288@godzilla.zeta.org.au>

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>Here's a question for any poor sucker with low-level BIOS experience :

>If I rewrite the BPT with a new geometry for the disk, can I assume that
>subsequent BIOS activity will honour the new geometry?  

>My guess is no, but it's always worth dreaming 8)

No.  The (DOS) BPT reflects the BIOS geometry at the time the partition
was formatted.  If you change the BIOS geometry (which can be changed
at least for IDE drives under AMI BIOSes simply by typing the new
geometry in the BIOS setup), then the BPT would have to be changed to
match.  The BPT is one of the few file system tables that (stupidly)
depends on the BIOS geometry.  If you change just the BPT, then DOS
may use the changed geometry, but since it doesn't match the actual
(current translated) geometry, it won't work.

Bruce



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