Rich Wonneberger wrote in a message to Frank Ramsey:
> You don't have to have the BIOS disabled on the 2nd one.  If you happen
> to have disk ID 0 on both HDA's which one it boots from becomes 
> somewhat interesting.  Easy thing to do is not have a ID 0 on the 
 RW> I thought the drive on the card with the lowest address is
 RW> the one that boots..  At least I think I read something like
 RW> that when I set up duplexing at my last job using Adaptec
 RW> 1542's..
 RW> I think this also is why when there's IDE & SCSI mix'd in a
 RW> system the IDE boots first..  They have the lower address.
The boot order is determined by ROM BIOS.  On most controllers, such as the 
Adaptec, the lowest SCSI Physical Unit Number (PUN) is booted first.  On 
other controllers, such as the IBM PS/2, the highest SCSI PUN is booted 
rst.
The order in which different controllers of the same type are scanned is 
specific to the firmware of each brand and model.  For example, and Adaptec 
AHA-1542 will scan 330h, 334h, and so on.
The order in which different controllers of different types are scanned is 
usually defined by the addresses of the BIOS extension ROMs.
IDE is generally booted before SCSI because the boot is handled by native 
BIOS.
 
-- Mike
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