INT 13 is the BIOS level call in a computer subsystem so you can boot off a disk. You can set a SCSI disk for boot by enabling the BIOS in the adapter it is connected to, and creating a primary "active" partition on that drive.
ATA/100 and SCSI can coexist in the same system, although connected by different adapters. You need a SCSI adapter for the SCSI device. Most PCs have IDE ATA/100 interfaces built into the motherboard. The SCSI adapter would go into a free PCI slot.
This was first published in October 2001