BIOS Flashing with a Bootable CD-ROM


I wanted to update the BIOS on my computer but faced a problem: no floppy drive and no DOS or Windows. Most BIOS flashing programs require either a floppy or DOS/Windows or both because the flashing programs run from DOS (Uniflash is a notable exception). Fortunately, smarter people than me worked out the details. Here are the steps, which presume you have boot-capable CD-ROM.

  1. Create a directory in which to work. I'll refer to it as $WORKDIR in this document:
    $ mkdir $WORKDIR
    $ cd $WORKDIR
  2. Download your updated BIOS image into $WORKDIR.
  3. Obtain a DOS boot image — you can probably use one from the FreeDOS project, but I ended up using one from, boot98sc.exe. Save or copy this file into $WORKDIR.
  4. boot98sc.exe is a self-extracting ZIP archive, so unzip it into $WORKDIR:
    $ unzip boot98sc.exe
    Archive:  boot98sc.exe
    warning [boot98sc.exe]:  105508 extra bytes at beginning or within zipfile
      (attempting to process anyway)
    file #1:  bad zipfile offset (local header sig):  211016
      (attempting to re-compensate)
      inflating: boot98sc.IMA

    As you can see in the output, in this case, the bootable image is boot98sc.IMA.

  5. Mount the bootable image using the loopback device:
    # mount -t vfat boot98sc.IMA /mnt/temp -o loop,rw

    You will need to be root to mount the image and you will also need to make sure that your mount point (/mnt/temp, in this case) exists.

  6. Delete enough unneeded .exe files from the image to make room in the image for your BIOS update file and flashing program. The bootable image has a fixed size, 1,474,560 bytes, which is precisely the size of a floppy disk. However, while the image is that size, the files it contains do not necessarily use all of that space:
    $ du -b /mnt/temp
    1453799 .

    So, the trick is to figure out how much space you need and delete enough non-essential files from the image to make room for your BIOS image and the flashing program. In my case, the required space was approximately 570,000 bytes:

    -rw-r--r--  1 kwall users  46414 2006-01-02 23:34 awflash.exe
    -rw-r--r--  1 kwall users 524288 2006-01-02 23:31 w7093ae7.405

    So, I deleted the following files:

    • scanreg.exe
    • scandisk.*
    • extract.exe
    • edit.*
    • drvspace.bin
    • fdisk.exe
    • smartdrv.exe
    • xcopy32.*
    • mem.exe
    • chkdsk.exe
    • move.exe
    • deltree.exe

  7. Copy your BIOS update file and flashing program into the mounted boot image:
    # cp awflash.exe w7093ae7.405 /mnt/temp
  8. Unmount the boot image:
    # umount /mnt/temp
  9. Create a bootable ISO image. Thus:
    $ cd $WORKDIR
    $ mkisofs -o bootcd.iso \
    > -b boot.IMA \
    > -c \
    > ./boot.IMA
    • -o bootcd.iso tells mkisofs the name of the ISO image.
    • -b boot.IMA tells mkisofs where to find the bootable image to use.
    • -c tells mkisofs the name of the boot catalog file that a bootable CD-ROM must have (you don't have to create it because mkisofs creates it for you).
    • ./boot.IMA tells mkisofs what files to put in the ISO.
  10. Burn the ISO image using your preferred burning application.
  11. Boot from the CD-ROM and run the flashing program according to the maker's instructions.

Additional Resources

As mentioned at the beginning of this document, I relied on the work other people did before. I've merged and synthesized elements from the pages listed below:

I suggest using a rewritable CD because, at least in my case, it took several tries to find the right boot image. You might not have this problem, but having a few rewritable CD media laying around might prove useful in the general case.

No guarantees implied or expressed. If it breaks, you get to keep both pieces.
#endif /* DISCLAIMER */