Format of parameter block for function 6Fh:
Offset	Size	Description	)
 00h	BYTE	(call) length of this buffer (in bytes)
 01h	BYTE	(ret) number of bytes in parameter block actually used
 02h	BYTE	(ret) drive flags (see #01571)
 03h	BYTE	(ret) physical drive number
		00h-7Fh floppy
		80h-FEh hard
		FFh no physical drive
 04h	DWORD	(ret) bitmap of logical drives associated with physical drive
		bit 0 = drive A:, etc.
 08h	QWORD	(ret) relative block address of partition start