From:	"Adam Schrotenboer" <ajschrotenboer AT galaxycorp DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Bios Geometry
Date:	Wed, 1 Jul 1998 16:33:50 -0400
Organization:	Triton Technologies, Inc
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Message-ID:	<6ne6fb$pko$1@news1.triton.net>
References:	<C77AD5DA2AA7D111859D00805FA72468033685 AT EXPRESS7>
NNTP-Posting-Host:	hol-ppp193.triton.net
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I'm no expert, but I have two guesses, though intertwined.

First, many HD's have a "diagnostic" cylinder, which allows low-level
testing and formatting of a cylinder w/o losing the data on the drive.

Second, on most HD's the partition doesn't include the "diagnostic"
cylinder. biosdisk may be returning data on the partition, not the physical
drive.


MetcalJM AT utrc DOT utc DOT com wrote in message ...
Hi,

I was wondering if anyone can explain a strange phenomenon to me.
I am using the cmd 8 to the "int biosdisk" library function (header in
<bios.h>) to retrieve the geometry of my hard drive. What I receive
back, tells me that my geometry is:

cyls: 522    (return val 521 + 1 for starting at 0)
heads: 64   (return val 63 + 1 for starting at 0)
secs/track: 63 (return val 63 + 0 for starting at 1)

I've used two other utilities to confirm these parameters.  They
report the correct number of heads and secs/track, however, the
number of cylinders is off by 1.  (They are reporting 523).  Other
calculations based on the size of my partitions also seem to agree
with the 523 number.

Can anyone tell me why biosdisk, which I understand uses the
DOS INT 0x13 call, is reporting 1 less than the proper number or
cylinders?

Here's more info on my system and gcc:

My BIOS uses LBA, so the real geometry is   c: 2095   h: 16   s/t: 63
b/s: 512
gcc version 2.8.1


Thank You for any ideas you can provide.

Reagrds,

JM
> -------------
> Jeffrey M. Metcalf
> United Technologies Research Center
> metcaljm AT utrc DOT utc DOT com
> (860) 610-7576
>
>

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