"johannes" wrote in message
Mike Walsh wrote:

Some system BIOSs will allow you to specify which SCSI adapter to boot with. Most will boot from only the first SCSI adapter
that loads its BIOS. A real SCSI adapter will allow you to disable its BIOS. The ATA cards I have seen that emulate SCSI don't
allow you to disable the BIOS; you most change PCI card slots to change which card will be used to boot.


AFAIK, it is much simpler. It is not a SCSI emulation, it is just that the
BIOS option 'Boot from SCSI' makes the motherboard look for the boot device
on the PCI BUS,

where is expects to find an alternative device, but not necessarily a SCSI.

But very likely of subClass SCSI.

The device type SCSI/PATA/SATA has really nothing to do with PCI,

Wrong.
PCI IDE add-in cards (or even chipsets integrated on the MoBo) identify
by device class, one of such is subClass SCSI.
Add in PATA cards use Class "Storage controller", subClass "SCSI".
SATA controllers now have (can have) their own SATA subClass.

it comes in much later by the type of disc connector card you plug
into the PCI.