INT 15 - APM SL Enhanced v1.0 - SL HW PARAMETER                                 
	AX = 5380h
	BH = 7Eh
Return: AL = ???
	    03h on A-Step 386SL BIOSes
	    12h on later steps
	BX = Control port (00B0h)
SeeAlso: AX=5380h/BH=00h,AX=5380h/BH=7Fh