SCSI BIOSes when present are PROM based programs that occupy space in PC High Memory between CC00 and EFFF. They utilize a 55AA signature that allows the motherboard BIOS to recognize BIOSes on plug in cards and initialize them prior to loading an OS. Motherboard BIOSes have a provision to use the SCSI BIOS INT13 services to load an operating system from a SCSI disk drive using the SCSI BIOS provided services
In addition to providing disk IO services, the SCSI BIOS also interrogates, identifies, and initializes the devices on the SCSI bus. While this could be done later by the operating system, many OSes assume that the BIOS will handle this.
http://www.scsifaq.org/scsifaq.html" The English Version of this file seems to have gone missing. Here is a link to the German version http://web.archive.org/web/20060426024859/http://www.dawicontrol.com/german/html/scsifaq.htm
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