INT 2F - INTERLNK - INSTALLATION CHECK                                          
	AX = 5600h
	DX = magic value FFFFh
	BL = instance number (00h = any, 01h = first loaded, etc.)
	(BH = 00h and CX = 0000h, see note)
Return: AL = FFh if installed
	    BL = instance number
	    CX = version number (CL = major, CH = minor)
	    DX = resident CS of driver, DX:0000h -> header (see #02845)
Notes:	INTERLNK was derived from Sewell Development Corporation's FASTLYNX.
	Some Microsoft software explicitly clears the BH and CX registers
	  before calling this function.
BUG:	reportedly, the MS-DOS INTERSRV program (though not INTERLNK) causes
	  serious FATsee File Allocation Table corruption and data loss when run under Novell DOS 7.
	  INTERSRV apparently checks for DR-DOS by testing the "OS"
	  environment variable for the value "DRDOS", which is no longer
	  correct for PalmDOS, Novell DOS, or OpenDOS.  A workaround may be
	  to explicitly set the OS variable to "DRDOS".
SeeAlso: AX=5601h,AX=5602h,INT 60/AX=0000h


Format of Interlnk device driver header:
Offset	Size	Description	(Table 02845)
 00h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	pointer to next driver, offset=FFFFh if last driver
 04h	WORD	device attributes (see #01647,#01648)
 06h	WORD	device strategy entry point
 08h	WORD	device interrupt entry point
 0Ah  8 BYTEs	character device name "NUL2    "
 12h 165 BYTEs	???
 B7h 67 BYTEs	fully qualified Interlnk filename
 FAh  6 BYTEs	???
100h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	pointer back to Interlnk filename at offset B7h
104h  8 BYTEs	???
10Ch	BYTE	total number of redirected drives
10Dh	BYTE	first local drive number (0=A:)
10Eh	BYTE	printer redirection (0=no, 1=yes)
10Fh	BYTE	???
110h  3	BYTEs	LPT1...3 status (0FFh=invalid)
113h 26 BYTEs	remote drive number (0=A:, 0FEh=unused) (refer to note below)
12Dh 26 BYTEs	always 0FEh ???
147h 26 BYTEs	always 0FFh ???
Note:	to obtain the remote drive number, subtract the value at offset 10Ch
	  from the local drive number before indexing into the table at 113h
	  (example: if local drives F, G, H are remote drives C, F, E then
	  the first three bytes at offset 113h are 02h, 05h, 04h)
	for each instance of Interlnk, an extra device driver is loaded, but
	  all have the same device name NUL2
SeeAlso: #01646 at INT 21/AH=52h