El Torito (CD-ROM standard)

El Torito is a specification that describes how CD -ROM should be formatted so that computers that are adapted by a corresponding BIOS can boot directly from CD- ROM without the prior installation of an operating system on the hard disk drive is required.

The specification was issued in January 1995 by Phoenix Technologies and IBM and is now widely accepted. It allows users to boot in three different ways:

  • Booting into a bit-for- bit copy of a hard drive
  • Booting into a bit-for- bit copy of a floppy
  • Booting a program code

At the start of the disk copy refers to a MS -DOS or Windows - compatible operating system the drive containing the CD -ROM as C:, all other hard drives start at D:. The robust variant is the start of a floppy image ( on the CD). In this case, the CD-ROM with A: designated by an MS-DOS or Windows compatible operating system. The original floppy drive A can then use B: to be addressed.

The code, however, is loaded at startup directly into memory and executed there. This option is often used by boot loaders.