INT 21,44,E / IOCTL,E - Get Logical Drive

	AH = 44h
	AL = 0E
	BL = physical drive number (0=default, 1=A:, 2=B:, 3=C:, ...)

	on return
	AX = error code if CF set  (see DOS ERROR CODES)
	AL = logical drive number assigned to physical drive
	   = 0 if drive accessed by only one drive specifier
	   = 1 if drive A:, 2 if drive B:, etc

	- used to determine the last drive designator used to access
	  a drive if more than one logical drive designation applies
	  to a device
	- implemented from DOS 3.2