This is a picture of the top of a 660 showing 2 drives. The red arrow is pointing to the button of the first drive, the green box is around the button of the second drive. First of all, an optical drive can be a CD, DVD, or BluRay drive. The button isn't invisible, it's just hidden in plain site by design. The previous pictures show its location, but here is one more. The buttons are the vertical, rectangles that are flush with the drawer and case.