INT 2F - MSCDEX (MS CD-ROM Extensions) - INSTALLATION CHECK
	AX = 1100h subfn DADAh
	STACK: WORD DADAh
Return: AL = status
	    00h not installed, OK to install
		STACK unchanged
	    01h not installed, not OK to install
		STACK unchanged
	    FFh installed
		STACK: WORD	ADADh if MSCDEX installed
				DADBh if Lotus CD/Networker installed
Note:	although MSCDEX sets the stack word to ADADh on return, any value other
	  than DADAh is considered to mean that MSCDEX is already installed;
	  Lotus CD/Networker v4+ uses this feature to fool MSCDEX into
	  thinking it is already installed when it is in fact CD/Networker
	  that is installed
Index:	installation check;Lotus CD/Networker
Index:	Lotus CD/Networker;installation check