Format of DoubleSpace DSPACKET structure:
Offset	Size	Description	)
 00h	WORD	signature 444Dh ("DM")
 02h	BYTE	command code
		53h ('S') get ??? for specified drive
 03h	WORD	result code
		(ret) 4F4Bh ("OK") if successful, else unchanged
 05h	DWORD	(ret) pointer to 96-byte ??? data
 09h	DWORD	(ret) pointer to ??? data
 0Dh  3 BYTEs	reserved