Even if you are installing from CD-ROM, you need two high-capacity floppy disks (either 1.2M or 1.44M). These disks are the boot and root floppy disks. The boot floppy disk holds the kernel that is used to start Linux the first time, leading to your installation. The root floppy disk holds a small filesystem that includes utilities needed for the installation. The two disks together form a complete and very small implementation of Linux. Enough of a system is on the two floppy disks to play with Linux, although many of the utilities are missing.

In most cases, the boot and root floppy disks are copied from existing files called images. The image is a precompiled version of the system that you duplicate on the floppy disks, eliminating the need to start from scratch. CD-ROM and FTP distributions have directories for several boot and root images, depending on the hardware on your system. You must select the images that match your hardware as much as possible, copy them to the floppy disks, and start your system with the floppy disks. You can do most of these steps from DOS, although you can’t use the DOS COPY command to create the boot and root floppy disks. You must create the floppy disks with a utility that ignores the DOS formatting. This utility, commonly called RAWRITE.EXE, is included with most Linux software distributions.