The Internal HD Formatter does not work like HD SC Setup. Internal HD Formatter looks to see if the ATA driver is loaded and if there is an entry in the drive queue for the IDE drive. Internal HD Formatter does not work directly with the drive as HD SC Setup does.
If the internal drive is set to be the startup disk in the Startup Disk control panel, booting with the command, shift, option and delete (CSOD) keys down prevents the driver from being loaded and the entry in the drive queue from being created. This is what the CSOD key sequence is designed to do.
On SCSI computers there is a patch that later mounts the drive. This patch was put in to help with mounting slow SCSI drives. The startup disk can be prevented from mounting on SCSI machines by zapping PRAM and pressing the CSOD on the same boot. This clears the patch's list of drives that are supposed to be attached.
The Macintosh OS maintains a data structure in memory called the drive queue. The queue stores information about the drives available. They do not have to be physical devices. The Mount Image control panel creates eight entries in the drive queue so it can mount eight disk images.
Since the CSOD key sequence prevents the disk driver from being loaded and drive queue entry from being created, Internal HD Formatter is lost and displays the message that no ATA device is available.
The work around for this is to boot the machine and select some other drive as the startup disk. When this is done, the CSOD key sequence does not need to be used and the internal should mount. If the Finder displays a message stating the internal drive cannot be mounted because of some error, Internal HD Formatted will still be able to work with the drive since the driver and drive queue entry exist.
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