CD & DVD: Das Boot

When your computer first powers up, it automatically looks for a boot device which contains special system files. Usually, the boot device is a hard drive, floppy drive, or CD-ROM drive that contains the files which allow the computer to begin loading the operating system it needs before it can do any useful work.

There are some operations that can't be done with a standard system disk, but which still need a bootable disk of some kind, such as hardware testing, low-level disk maintenance and flash upgrades. CD and DVD burning software packages such as Easy CD Creator and Nero can create bootable CDs, but there's a catch - they can do it only if you already have a bootable floppy disk! Windows XP is delivered as a bootable CD-ROM, and on current computers there is little point in having a floppy drive or floppy disks. So we need some way to make a bootable CD-ROM with the required program files.

Say we need to upgrade the BIOS of a motherboard in a computer that has no floppy drive. We need to boot from a CD-ROM which also contains the flash update program and its data file, and then run the update utility. I ran into this situation a few months ago, and none of the usual CD burning utilities could produce a bootable disk without a bootable floppy.

These instructions assume you're using Windows XP. It's a good idea to use a CD-RW disc so it can be rewritten in case of mistakes. The four files you need to create a bootable CD can be downloaded from the Web, and they're small enough not to strain a modem. These files are:

Create a folder to hold the working files needed to make your bootable CD-ROM. I used c:\temp\bcd, named after the Build CD utility to be placed in it. Unzip the contents of, including its subfolder, into your bcd folder. You should have several files and a sub-folder called 'bin' - in this example, it would be c:\temp\bcd\bin.

Wnaspi32.dll is an ASPI library file which provides a low-level command interface to CD-ROM drives and is needed to burn a CD. Copy wnaspi32.dll into the 'bin' subfolder of bcd. contains the Build Floppy Disk utility that will be used to emulate a bootable 2.88MB floppy disk on the bootable CD we're putting together. Unzip the contents of, including its five subfolders, into the c:\temp\bcd folder. You'll be asked if you want to replace some existing files - answer 'yes'.

Next, there's, which provides a template for the clean bootable disk. Extract its contents into the c:\temp\bcd folder. Check that the contents of your bcd folder are the same as those in the screenshot at left. All the files and folders need to be in the right places.

The final step in prep­aration is to add the BIOS update files to the folder c:\temp\bcd\cds\clean\bootdisk (not the 'files' folder). These files will vary depending on the motherboard, and will be available from the manufacturer's Web site as DOS utilities.

Now you're ready to burn the disc. Do this by opening a command prompt (click Start-Run, type cmd into the text box and click <OK>. Change to the bcd folder by typing cd \temp\bcd then clicking <OK>. Now, activate the CD burner by typing bcd clean and clicking <OK>. You should be rewarded by several screens of technical information about what the program is doing, followed by the message 'CD: Exiting with return value 0'. This means the write was successful, and you now have a bootable CD-ROM containing the BIOS update files.

Click here to see a screen shot of the contents of the bcd folder with all the required software installed.

Click here to see a screen shot of the Build CD program which givesa verbose description of its activities, which can be useful if there are problems.

Booting Bart's Way

This Web page, at, is an extensive guide to producing many different types of bootable CDs, with functions ranging from simple disk utilities, through multiple operating systems, to automatic installations of Windows, complete with the latest service packs.

Bart's page can walk you through the creation of a variety of boot CDs. Although it seems a little complicated at first, you can safely disregard most of the technical explanations at the top of the page and use the step-by-step guides.

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