FreeDOS USB stick

FreeDOS bootable USB

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Here you can download a prebuilt bootable FreeDOS image file for use on an USB flash drive.

The image file is available in different sizes. Each has an FAT 16 filesystem which can be mounted and written to by nearly any operating system. This way you can put additional files onto the stick after you have written the image. The 256MB and 2048MB images differ only in free space. They both have the same FreeDOS 1.1 installation on it. That is the reason for both image files being only 7 MB in size – they will grow when uncompressed.

The 30M image has been created upon user request: It contains the base installation of FreeDOS only and was used to update the firmware of a bunch of servers via PXE network boot.

Why FreeDOS?

I needed to update the firmware of my HP Proliant Microserver. The firmware update boots FreeDOS from CD-R, but I didn't have an optical drive built into my server. So I was looking for some way to get FreeDOS to boot off an USB stick.

The 30M image file can be PXE-booted over the network and this was used to rollout firmware updates to a bunch of servers.


  • Download the image file which fits on your USB stick:
Filename Download size use for…
SHA1: ac39e00910f20f0ecc378899286d5eb66d3c5a52
3,0 MB …small USB flash drives and PXE network boot.
Only the FreeDOS base package is included.
SHA1: 38e83a800d4da970cc98e20f7ee95503d0253b00
6,7 MB …USB flash drives between 256 MB and 2 GB in size
SHA1: 187ce046066b7a70039a46d7c3a24dd52a8dc049
6,7 MB …USB flash drives larger than 2 GB in size

The files are bzip2-compressed. Don't forget to uncompress the file before writing it to your USB flash drive!

Older releases are still available for download on my FTP server: (via HTTP, preferred) (via FTP, deprecated)

          ^^^          ^ ^^^^
           |           |   `-- Minimum size of USB stick to put this image on
           |           |
           |           `------ Number of release
           `------------------ FreeDOS version used


Installation is rather simple if you have some Linux- or *BSD-based system at your hand. For Windows, you need something that works like dd – see below.

Linux / BSD

  1. Download the image file which fits on your USB stick.
  2. Unpack the image file with bunzip2 or a similar tool:

    bunzip2 FreeDOS-1.1-memstick-2-256M.img.bz2

  3. Use dd to copy the uncompressed image to your USB flash drive::

    dd if=FreeDOS-1.1-memstick-2-256MB.img of=/dev/sdz bs=512k

  4. This command takes some time; replace /dev/sdz with the actual device name. Omit the partition number. Use the device name referring to the whole disk. On Linux, something like /dev/sdz is ok, but /dev/sdz1 or /dev/sdz4 would not work as it addresses the partition of a disk.

  5. Issue the sync command to ensure all buffers are written to disk:


  6. You are done as soon as sync has finished and returns to your shell prompt! Reboot from the USB flash drive and it should boot into a boot menu. Press enter once and it should boot FreeDOS, with FreeDOS presenting you its own start menu. Here you can choose whether you want to load any memory managers.


  1. Download the image file which fits on your USB stick.
  2. Uncompress the image file with 7-Zip or a similar tool.
  3. Use Win32 disk imager or dd for windows to write the uncompressed image to your USB flash drive. See below for details.
  4. You are done! Reboot from the USB flash drive and it should boot into a boot menu. Press enter once and it should boot FreeDOS, with FreeDOS presenting you its own start menu. Here you can choose whether you want to load any memory managers.

Win32 Disk Imager

Win32 Disk Imager is my recommended choice fo writing images. This tool has a graphical user interface which makes writing images easy.

Be very careful with image writer software! Choosing the wrong target may result in overwriting files or even hard disks and there will be no warning if you do!

dd for windows

dd for windows is a command line tool, just like the original dd command on Linux.

I've tested writing the image with "dd" for Windows and this worked for me, but you really should feel confident in working on the command line.

Open a Windows command line by running cmd.exe and change into the directory holding the downloaded and unzipped files. The command options I used for writing the image looked like this (but don't just copy them – read below!)

C:> dd if=FreeDOS-1.1-memstick-3beta.img of=\\?\Device\HarddiskX\Partition0 bs=512k --progress
You need to replace HarddiskX with the correct device name of your USB stick! Use dd --list to get a list of devices found on your system.

Advices for doing a BIOS or firmware upgrade

It is perfectly fine to use your freshly made USB stick to boot into FreeDOS and apply a firmware upgrade. That is actually what I used this USB stick for in the first place. Here are some advices that may be helpful:

  • After writing the image, check that it is in fact bootable. If it is, plug the USB stick into the computer where you have downloaded the firmware files. It doesn't matter if it is running Windows, Linux, MacOS or whatever. The stick should show as a new drive holding some files (e.g. autoexec.bat, config.sys, syslinux.cfg, …) and the directory FDOS. Just copy the firmware files over to the USB stick. If they are in a compressed format (like *.ZIP, *.7z), extract them first and put the resulting files onto the stick.

  • When booting from the USB stick, the first boot menu is from the syslinux bootloader. Just press enter here and it should boot into FreeDOS, which displays its own boot menu for about five seconds. I recommend you to choose option 4 here ("4 - Load FreeDOS without drivers"). This ensures the CPU is running in real mode which is highly recommended for any kind of firmware update.

FreeDOS boot menu

Technical Notes

  • The partition size is actually 250 MB for the 256 MB image, or 2000 MB for the 2048 MB image, with FreeDOS taking up about 32 MB. The remaining space can be used for additional files.

  • It is no problem to use larger flash drives, but you will still only see a 250 MB or 2000 MB partition.

  • FreeDOS has support for long file names, but I recommend to stick to the old 8.3 naming scheme.

  • Read the old howto or the new image generation howto if you want to make a bootable USB drive or a bootable image on your own. You can create any filesystem size supported by FAT16 or FAT32.

How did you do this? How can I build my own?

Should you want to make your own image file from scratch, please read the FreeDOS boot image generation HOWTO. You will need Linux and some open source tools for this.




  • Added SHA1 checksums for downloads.
  • sync command added after writing image with dd. Ensures the buffer is written to disk before removing the USB flash drive.


  • More than 1000 downloads in August 2014!
  • Added some general tipps for firmware flashing.


  • Added some quick and dirty navigation menu.
  • The new HOWTO was meant to supersede the old HOWTO, but as the old HOWTO is still visited very often I will keep it online.


  • Made some updates to this page.
  • Added websites which have linked to this page.


  • Added 30MB image with only the BASE-package of FreeDOS


  • Added ODIN floppy disk image

These websites might be helpful, too:

Websites that have linked to this page:


  • – allows you to create a bootable Live USB drive for FreeDOS, FreeBSD, Arch Linux, Ubuntu and a lot more distributions or operating systems. It runs on Windows, Linux and Mac OS X.

Last update: September 21, 2014

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