FreeDOS to Oberon System 3

By R. S. Doiel, 2019-07-28 (updated: 2019-08-19)

What follows are notes on getting a FreeDOS 1.21 and then Native Oberon2 running under VirtualBox 6.0. You might wonder why these two are together. While it was easy to run the Native Oberon installation process that process assumes you have a properly partitioned hard disc and VirtualBox seems to skip that process. I found taking advantage of FreeDOS simplified things for me.

My goal was running Oberon System 3, but setting up a Virtual Box with FreeDOS 1.2 gave me a virtual machine that functions like a 1999 era PC. From there all the steps in the Oberon instructions just worked.

Creating FreeDOS 1.2 Virtual Box

I’ve been doing a bit if computer history reading and decided to bring up some older systems as a means to understand where things were. The first computers I had access to were 8080, 8086 machines running MS DOS based. My first computer programming language was Turbo Pascal. Feeling a bit nostalgic I thought it would be interesting to use it again and see what I remembered from the days of old. While PC and MS DOS no longer exist as commercial productions an wonderful group of Open Source hackers have brought new life into DOS with FreeDOS 1.23. You’ll find many of your old familiar commands but also some nice improvements. You can even run it under VirtualBox which is what I proceeded to do.

VirtualBox 6.0 setup

The FreeDOS website includes a CD ROM image that you can use to install it. There are couple small hitches though to get it working under VirtualBox. First go to the download page and download the CDROM “standard” installer.

While that is downloading you can setup your VirtualBox machine. First to remember is DOS compared to today’s operating systems is frugal in its hardware requirements. As a result I picked very modest settings for my virtual machine.

  1. Launch VirtualBox
  2. From the menu, pick Machine then pick new
  3. Name your machine (e.g. “FreeDOS 1.2”), select the type: “Other” and Operating system of “DOS”
  4. Set memory size as you like, I just accepted the default 32MB
  5. Hard disc, pick “Create a virtual hard disc now”
  6. Hard disc file type, pick “VHD (Virtual Hard Disk)”
  7. Storage on physical hard disc, I picked Dynamically allocated both either is fine
  8. File location and size, I accepted the default location and size
  9. Before starting my FreeDOS box I made a couple of changes using “settings” menu icon
    1. Display, I picked bumped memory up to 128M and picked VBoxSVGA with 33D acceleration (for games)
    2. Storage, I added a second floppy drive (empty)
    3. Network, I picked attached to NAT
  10. When looking at my virtual machine’s detail page I clicked on the Optical drive (empty), click “choose disc image” and pointed at the downloaded isntalled CD
  11. Click Start.
  12. At “Welcome to FreeDOS 1.2” blue screen, hit TAB key
  13. Add type a space than add “raw” (without quotes) press enter
  14. Follow the install instructions, when you get to “Drive C: does not appear to be partitioned” dialog, pick “Yes - Partition drive C:”
  15. On the next screen pick “Yes - Please reboot now”
  16. When at the “Welcome to FreeDOS 1.2” scren hit TAB again
  17. Add the space raw " row" to the command and press enter
  18. Pick “Yes - continue with the installation”
  19. Pick “Yes - Please erase and format drive C:”
  20. At this point its a normal FreeDOS install
  21. When the install is done and reboots choose the “boot from system disc”,you now should have a working FreeDOS on VirtualBox

Native Oberon System 3 on Virtual Box

Native Oberon can be found at There is a related ftp site4 where you can download the necessary files for the stand alone version.

Here’s the steps I used in my Mac to download Native Oberon and into a file on my desktop called “NativeOberon-Standalone”. Open the macOS Terminal application. I assume you’ve got a Unix command called wget already installed5.

       mkdir -p Desktop/NativeOberon-Standalone
       cd Desktop/NativeOberon-Standalone

Clone your FreeDOS Box first. You’ll want to do a “Full Clone”. You’ll also want to “remove disk from virtual drive” for any optical discs or floppies. You do that from the virtual boxes’ detail page and clicking on the drive and picking the “Remove disc from virtual drive” in the popup menu.

At this point we have a virtual machine that is very similar to an 1999 era PC installed with MS DOS. Normally you’d install Native Oberon via 1.44MB floppy discs. In the folder of you downloaded there is disc image called “oberon0.dsk”. This is used to install a minimal Oberon System. What about the rest of the Oberon System? How do we get the rest of the files onto a virtual floppies? This wasn’t obvious to me at first.

Making the floppy disc images on macOS

Use can use “Disk Utility” to create floppy disc images on a Mac. Unlike creating CD images you want to first use the blank image. From the menu click on File -> New Image -> Blank Image (or use the shortcut command key and “N”). You should then see a model dialog box. This dialog lets you set the name of the image file. You need to set the size to “1474560 B”. Set format “MS-DOS (FAT)”. Set encryption of none. Set partition type of “Single partition - Master Boot Record” and image format set to “read/write”. Once the disc image is created you can then mount the empty disc image by clicking on it in finder. Next drag the appropriate file(s) into the image. Unmount (eject) the image. At the point you should have a floppy image suitable to mount from the Virtual Box VM’s “floppy drive”.

Making the floppy disc images on Linux

On Linux I used the mkfs.mkdos with the “-o” option to set the image name and just created the images from the folders with each folder holding the appropriate file.

Making the floppy disc images from FreeDOS

Another approach would is to use FreeDOS. I create an iso image of the Oberon installation directory and mounted that as a CD under FreeDOS. Next I used Virtual Box’s “create a new floppy disc” to create an empty unformatted 1.44 MB disc which I think formated using the DOS command “format a:”. Once completed I copied the files to the “a:” drive also using the DOS copy command.

In either case make sure the formatted floppy disc images are FAT12 or FAT16. FAT32 came about after this version of Oberon was developed so it may not be readable for installation.

Organizing the install discs

The Oberon install discs were organized as follows. The “oberon0.dsk” is initial disc to install a minimal Oberon System. Once it’s installation is complete (described in install.txt in the Oberon System 3 Stdalone directory) you can then follow the steps to install the rest of the system, source code and documentation. E.g. gadgets1.arc contains the install for Gadgets desktop environment and is an interesting look at how Oberon took a different path for (similar to RISC OS) for a GUI.

sizes are in MB, compressed, then uncompressed
Oberon-0 oberon0.dsk 1.4 0
Gadgets gadgets.arc 1.4 (2.9) 1
Documentation docu.arc 1.3 (2.5) 2
Applications apps.arc 1.3 (2.8) 3
Tutorials tutorial.arc 0.3 (0.8) 4
Pr3Fonts pr3fonts.arc 0.3 (0.6) 4
Pr6Fonts pr6fonts.arc 0.5 (1.8) 4
Source1 source1.arc 0.9 (2.5) 5
Source2 source2.arc 1.2 (3.5) 6
Source3 source3.arc 0.6 (1.7) 7

  1. FreeDOS is an Open Source implementation of PC/MS DOC↩︎

  2. Native Oberon is a 1990’s version of Oberon System running on i386↩︎

  3. Download FreeDOS from↩︎

  4. Download Native Oberon Stand Alone from↩︎

  5. wget is easily installed with HomeBrew or Mac Ports↩︎