[Toaster]

Keep in mind the following when dealing with EIDE/IDE devices in a "master/slave" combination.
In the beginning of IDE which was pioneered by Compaqs own in house drive manufacturing facility (Connor Peripherals) among other manufacturers, is that the IDE device is a BIOS device interface meaning it must be serviced via BIOS calls. This is the reason why your system requires a drive to be represented with a "drive type".
This dates back to MFM/RLL/ESDI and removable media devices such as floppy drives. Still, EIDE has roots in the ST506 interface presented by Seagate with the introduction of the ST506 MFM hard-disk and a whopping 5MB of user memory.
(rotating memory array is the technical term)
(in the years of the MFM/RLL drives of Seagate manufacture, all drives were sold using maximum UNFORMATTED capacity. IE: ST506 6MB of unformatted capacity)
Drive makers needed an interface that was cheaper and could outperform MFM drives of the day. The first few implementations of IDE was propriatory to Compaq and data rates rarely exceeded 750KB/sec.
When to ATA compliant hard disks are used on the same channel, one of the drives "interfaces" is unused and only the drive logic is used while the "master" does all the work. This was the reason why IDE had problems in the early years due to incompatabilities.