Int 2F Fn 1500  - Cd-rom - Installation Check                              [d]

   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

See Also: AX=150Ch,AX=15FFh,INT 2F/AX=D000h"Lotus"