INT 2F - CD-ROM - INSTALLATION CHECK                                            
	AX = 1500h
	BX = 0000h
Return: BX = number of CD-ROM drive letters used
	CX = starting drive letter (0=A:)
	AX = 15FFh (Novell DOS 7 NWCDEX only!)
Notes:	this installation check DOES NOT follow the format used by other
	  software
	this installation check conflicts with the DOS 4.00 GRAPHICS.COM
	  installation check
BUG:	this function may return an incorrect starting drive letter when
	  INTERLNK is installed
SeeAlso: AX=150Ch,AX=15FFh,INT 2F/AX=D000h"Lotus"