Which device for IDE?

[Lemmink]

All drivers for all onboard controllers are called scsi.device (or 2nd.scsi.device when two are present like with the A4000T)

HDToolbox and the HDPrep Programm that were introduced with OS 2.0x have scsi.device set as default. While the first regular onboard controller on the A3000 (and the A2000 cardversion A2091) were actual SCSI controllers the name stayed when Commodore switched to IDE for A4000/A1200/A600
That way there was no need to change the default scsi.device setting and you could have one set of OS disks for all machines (A4000T is a different story)

[Lemmink]

Those two do not like each other. Actually when Installing OS 3.5 / 3.9 you are asked if you do have a 4-way adapter. If you say yes the scsi.device patch is skiped from the ROM update.