On Sep 6, 2006, at 11:40 AM, Hilt, Ian wrote:
Basically, I want to know where the BIOS gets the hard drive
parameters
when the Drive Type is set to "AUTO" in the BIOS configuration. The
best
I've been able to come up with from the internet is an "IDENTIFY"
command that purportedly
(<http://www.linux.com/howtos/Large-Disk-HOWTO-10.shtml>) gets its
information from the "IDE controller". This does not answer my
question
completely. Are the parameters returned by the controller hard coded
into a chip on the board or are they on the platters of the hard
drive,
or neither?
"Neither" is probably the best answer.
The hard disk has an on-board controller which answers the ATA
"IDENTIFY DEVICE" command with the hard drive parameters used by the
BIOS, assuming that the BIOS is operating in the legacy C/H/S mode
rather than the newer LBA mode which uses absolute block numbers.
Note that the answer the drive controller gives will normally be a
fabricated geometry which does not have anything to do with the
actual geometry of the physical device, in part because drives
nowadays keep a variable number of sectors per track rather than
using a CAV layout.
--
-Chuck
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