INT 21,44,D / IOCTL,D - Generic I/O for Block Devices

	AH = 44h
	AL = 0D
	BL = drive number (0=default, 1=A:, 2=B:, 3=C:, ...)
	CH = device type
	   = 08 for disk drive	(block device)
	CL = minor function code
	   = 40  set device parameters
	   = 41  write track on logical device
	   = 42  format/verify track on logical drive
	   = 47  set access flag  (DOS 4.x)
	   = 60  get device parameters
	   = 61  read track on logical device
	   = 62  verify track on logical drive
	   = 67  get access flag  (DOS 4.x)
	DS:DX = pointer to parameter block


	on return
	AX = error code if CF set  (see DOS ERROR CODES)


	- provides device independent primitive control operations
	- implemented from DOS 3.2
	- see IBM DOS Technical Reference Manual for more details