INT 21,32 - Get Pointer to Drive Parameter Table (Undocumented)

	AH = 32h
	DL = drive (0=default, 1=A:, 2=B:, 3=C:, ...)

	on return:
	AL =  FF if the drive number in DL was invalid
	DS:BX = address of drive parameter table (DPT)

	- available since DOS 2.0
	- used by DOS commands CHKDSK and RECOVER
	- forces a media check, which clears byte DS:[BX+17h] or DS:[BX+18h]
	  in the Drive Parameter Table
	- actually accesses the disk, causing a critical error if a disk
	  error occurs
	- can be used to determine if a drive is SUBST'ed by comparing
	  DS:[BX+1] and DS:[BX] for a match.  If not equal, then the
	  drive is possibly SUBST'ed (though not guaranteed, this may also
	  indicate a Bernoulli box)
	- can be used to determine if a drive is a RAM disk; if the disk is
	  NOT removable and (DS:[BX+1] == 0), then the disk is a RAM disk
	  (see IOCTL,0 bit number 0Bh to determine if the disk is removable)