CD Recording FAQ

6. Creating custom DataCDs
  6.5. Creating a bootable CD

Since floppy disks don't fit in the picture of modern computing, bootable cds become more and more popular. A lot of operating systems, especially Linux distributions, are distributed in the form of bootable cds, so that you can install them right from the scratch. Having a bootable cd for emergencies is also appealing.

To create bootable cds, a standard called El Torito was developed, which has been adopted by hardware manufacturers so that most modern motherboards and SCSI controllers support booting from a cd-rom drive.

The basic step to create a bootable cd is to have the image of a boot floppy. You can make one using a utility like raw write. Many cd mastering programs simplify the process by providing an option to create a bootable cd from a floppy without the need for making an image first.

The El Torito standard provides some options, the basic one being whether the cd will emulate a floppy or not. If you choose to emulate a floppy, then a drive letter a: will appear after booting, which will refer to the boot track of the bootable cd.

It is very easy to create and use a bootable cd, but some important points have to be noted.

If you wish to have access to your cd readers after booting, then you must prepare a boot floppy containing all necessary DOS drivers and the correct entries in config.sys and autoexec.bat, and use this to create the floppy image. For example, config.sys should look like this:

and autoexec.bat like this:

In order to boot from a bootable cd, you must set BIOS options properly. In BIOS settings, you have to find the Boot Sequence option and set it to boot from CD-ROM. If you use a SCSI controller (with its own BIOS), you can select to boot from your SCSI drive during booting, usually by pressing a key combination like <CTRL+B>.

Note that a bootable CD should be a single session one. It is highly advisable to close the cd at the time you create it.

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