Format of MDEBUG identification table:
Offset	Size	Description	)
 -2	WORD	entry offset
 00h	WORD	CS of MDEBUG
 02h	DWORD	old INT 08h vector
 06h	DWORD	old INT 09h vector
 0Ah	DWORD	address INT 16h routine used by MDEBUG
 0Eh	BYTE	length of version string
 0Fh  N BYTEs	version string