Int 13 Fn 06  - Adaptec Aha-154xa/bustek Bt-542 Bios - Identify Scsi Devi  [d]

   AH = 06h

Return: AH = status code (see #0166)
   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

See Also: AH=08h"PC",#0656 at INT 1A/AX=B102h