AP400 Professional Workstation

I'm trying to use one of these.....

It has the original SCSI drive installed. (About 4 GB)

When I plug in an IDE drive to the "primary" IDE connector it is
recognized. But the machine insists on trying to boot from it.

The boot order feature in the setup program can't seem to distinguish
between the two hard drives although other screens recognize all four
drives correctly (floppy, CD, IDE and SCSI).

Can anybody help me force the box to boot from the SCSI drive?

What is the maximum IDE drive size supported and how can in increase
it?

Thanks in advance....

am