> -----Original Message----- > From: Chuck Swiger [mailto:[EMAIL PROTECTED] > Sent: Wednesday, September 06, 2006 2:55 PM > To: Hilt, Ian > Cc: freebsd-questions@freebsd.org > Subject: Re: Origin of hard drive parameters > > 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.
Ok. Maybe the better question is: in either case, C/H/S or LBA mode, where are these parameters stored? > 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. > If CAV == Constant Angular Velocity, I thought this layout stored a variable number of sectors per track, as opposed to CLV which stores data at a constant density over the platters. Ian Graeme Hilt _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"