I would like to know how to connect a hard drive to the Amiga 4000 tower. I have an IDE cable from the top right m/b to the IDE CD-drive. I also have what looks like a SCSI cable from the CPU board.
Does this platform support both?
The Amiga A4000T is the only Amiga to include both a SCSI-II controller and an IDE interface on the motherboard. And, if you can believe the entry in the BBOAH is also THE RAREST home computer ever, with only ~35 known to exist. Note: This is referring to the units manufactured by Commodore, and not those that followed the bankruptcy. Anyway, she's a rare gem if the former.
Connecting an IDE HDD should be no problem. I would start by trying a known-working drive (or flash with some adapter) as the Master device, without the CD-ROM connected. You should be able to boot from floppy and recognize the HDD using the HD setup tools on your Workbench 3.1 Install disk. Use the tool to partition the HDD, then format it in the standard Amiga way. From there, you should be able to install Workbench, then reboot the machine directly from the HDD. Really, nothing special here, in comparison to other Amigas.
The Kickstart 3.1 ROM that was created for the A4000T is modified to allow the IDE and SCSI-2 controllers to have their own drivers and work either independently or together. For better performance, you should consider a SCSI HDD. Criticisms of the A4000 Desktop HDD performance with the IDE interface is the reason that Commodore revised the system to bring back SCSI (which the A3000/A3000T had built-in also).