Instead, the preferred method is to create a single file, an image of a bootable CD, called an ISO image. Just copying files to a CD will not work because the CD will need a master boot record and other hidden Startup operating system files. Just like the old boot floppy diskettes, CD or DVD-ROM discs can boot to a DOS or other operating systems. This document will cover How to use a bootable ISO image downloaded and methods for rendering an.