INT 13 - Adaptec AHA-154xA/Bustek BT-542 BIOS - IDENTIFY SCSI DEVICES

	AH = 06h
Return: AH = status code (see #00234)
	CF clear if successful
	    AL = first drive supported
		(80h nonconcurrent operation, 81h concurrent operation)
	CF set on error
Desc:	determine the number of the first supported SCSI drive
Note:	the return value is 80h when two SCSI drives are supported, 81h if
	  only one SCSI drive is installed
SeeAlso: AH=08h"PC",#00732 at INT 1A/AX=B102h