What year is this? 1990 or 2011? It sure doesn’t seem like 2011 if you want to update your BIOS. When it comes to that, most hardware makers are still living in the ’90s (because of the good music, I suppose) and they will happily provide you with update.exe. No, not a Windows program, a DOS executable.

And while I am usually happy to use things that “just work”, the problem is that it’s not that easy to boot a DOS disk on a modern computer. Or even to get a bootable DOS image. Obviously, floppy disk drives are long gone. That leaves CD-ROM drives and USB sticks.

Using a CD-ROM mostly works (there are bootable FreeDOS CD images), except when you want to also be able to write on them (let’s say, you want to backup your existing BIOS first). Not to mention that it’s not that easy to add files to a ISO file and using both the CD for booting and a stick for storing files is complicated. That leaves us only the USB stick to play with.

After trying at least 3 USB stick images found on the Internet and also trying to create one myself with sys-freedos-linux (and failing miserably), I decided to use the old “it’s a USB stick, consider it a hard-disk and please work” method. Here goes:

Step 0. Requirements. You’ll need a working VirtualBox install, the install ISO of FreeDOS (download fdbasecd.iso) and a modern USB stick (the kind that thinks it’s a hard disk, not the kind that thinks it’s a floppy).

Step 1. Create a new VirtualBox machine for FreeDOS. The FreeDOS install has a little over 6 MB, so a virtual disk of more than 25-30 MB should be enough for BIOS images and flashing utilities.

Step 2. Attach the FreeDOS iso to the virtual machine and install it. The FreeDOS setup program will guide you through all the installation steps (partition, format, copy files). A reboot will be necessary after partitioning.

Step 3. Start your new FreeDOS from the virtual machine’s hard disk to check all is working. Then shut down the machine.

Step 4. Convert the virtual hard disk to a raw disk image, run this:

$ VBoxManage internalcommands converttoraw /path/to/FreeDOS.vdi /tmp/FreeDOS.img

Step 5. Write the image to the USB stick. You’ll need to first plug it in, of course. Make sure you have the correct sdX (or you might overwrite your hard disk!)

$ dd if=/tmp/FreeDOS.img of=/dev/sdX

Step 6. Copy other files to the USB stick. On most systems, it’s enough to unplug the stick and plug it back in and it will be automagically mounted. If not, open a console and do:

$ sudo mount /dev/sdX1 /mnt/stick

Then use you favorite file manager/command line to copy the files.

Step 7. Boot your computer using the USB stick. You should have a working FreeDOS, including your BIOS utilities, and enough free space to backup/dump BIOS data.

… and if you’re in a hurry, you can download my FreeDOS image (51 MB hard disk image) and skip directly to step 5!

Enjoy

Related posts:

1. How to use a raw disk image file in VirtualBox
2. How to boot multiple CDs from a USB stick (with ext2 partitions)
3. How to boot multiple CDs from a USB stick (improved solution)
4. Ne trebuie hard-disk-uri mici
5. Some problems booting partitioned USB sticks and images in VirtualBox (with fixes)