How to install MS-DOS on a CF-card without using a floppy

Oracle VM

This information is based on and is more of a note to self. Anyway, as a retrocomputer enthusiast I often find myself in the following situation:

I have a compact flash to IDE adapter with a suitable CF-card. However, I do not have a floppy drive on the retrocomputer that I want to install MS DOS to. Furthermore, I also need to install Ontrack Disk Manager to utilize larger partitions on older computers. The proposed solution is to perform the install by using a Virtual Machine.


Now, I follow this procedure to install Ontrack Disk Manager and MS DOS 6.22 on the CF-card.

Step 1: Type:

wmic diskdrive list brief

to identify your cf-card’s DeviceID (it should look something like \.\PHYSICALDRIVE1)

Step 2: Change to the VirtualBox directory (usually c:\Program Files\Oracle\VirtualBox). Type the following to create a raw virtual machine (.vmdk) (replace N in \.\PHYSICALDRIVE1 with DeviceID).

vboxmanage internalcommands createrawvmdk -filename CompactFlashCard.vmdk -rawdisk \.\PhysicalDriveN

Step 3: Start VirtualBox with administrator rights.

Create a DOS virtual machine (other -> DOS), default settings, except for hard disk, where you choose “Use an existing virtual disk file”, where you assign the CompactFlashCard.vmdk-file that you created earlier.

From here, you can add your Ontrack Disk Manager and MS DOS disk images to the floppy drive of the virtual machine, and install MS DOS. Ontrack Disk Manager usually divides your CF-card to partitions of 2 gb each.

If you want to add additional files (games, drivers etc) to the cf card using your modern PC, you can just unplug and plugin the cf card in Windows and drag n drop software onto it.


  1. a

    I tried your instructions on a Win10 machine. I can crate the vdmk file on the CF card. However, since I deleted all the partitons, I cannot acces the vdmk file from the virtualpc menue (it shows the usb device but does not see a partition and does not let me open it…)

    1. Dreamcast (Post author)

      Hi Andreas! The vdmk-file is created on your computer, usually in the c:\Programxxx\Oracle\VirtualBox\ folder.

  2. Walter Wold

    C:\Program Files\Oracle\VirtualBox>vboxmanage internalcommands createrawvmdk -filename CompactFlashCard.vmdk -rawdisk \.\PhysicalDrive1
    VBoxManage.exe: error: Cannot open the raw disk ‘\.\PhysicalDrive1’: VERR_FILE_NOT_FOUND
    VBoxManage.exe: error: The raw disk vmdk file was not created

    1. Dreamcast (Post author)

      Is your cf-card’s DeviceID PhysicalDrive1 according to Step1?

  3. Walter Wold

    Yes that’s correct. I’ve typed in for listing first and changed N value

    1. Dreamcast (Post author)

      Did you run the command prompt as administrator? (needed to access physical drives).

  4. Walter Wold

    Thanks ! I forgot to use this function. Now I managed to install MsDos 6.22 . To bad my BIOS on my Compaq CDS524 W like CF card tough. Will have to try 2GB instead of 4GB.

  5. Walter Wold

    Now everything is sorted out! I reconfigured Bios setup twice, saved and everything works smooth. Two partitions with 2GB each. No notice!

  6. Sean H.

    Hello, thank you for this summary. This is what finally got my 486 to boot dos without a floppy. Have you been able to mount the other partitions on your CF card as extra drives through DOS? I’m not sure how this is accomplished.

    1. Dreamcast (Post author)

      Hi Sean. Great that you got your 486 up and running through this guide. I have not attempted to create additional partitions via MS-DOS, but I suggest trying Ontrack Disk Manager (see,, which can handle most type of partitions.

      1. Sean H.

        Thought I would report. I did use OnTrack to partition my drive as part of your steps, however DOS would not see them as logical drives; I didn’t see them at all.

        I have since gone into the BIOS and set the drive as ‘LBA’ mode. Now I have 4 logical drives for that disk, 2GB each.

        Thanks again.

  7. Dooser

    This worked brilliantly; thank you! I had previously tried to write existing images to the card, but none of them would boot.
    I used a laptop running Ubuntu in order to install DOS to the CF card. The only thing I had to change was to replace “\.\PHYSICALDRIVEX” with “/dev/sdX”. I also didn’t do any of the Ontrack stuff, since it was a 512MB card.

    1. Dreamcast (Post author)

      Hey, great to know that it works under Linux as well!

  8. RetroTech Chris

    Wonderful procedure! One thing I would add for people who want to re-mount the card and use it in the VM in a Windows environment: unless you do an exclusive lock on the volume, you won’t be able to write any files to the CF card. If you Google search for “User-mode Raw Disk Access”, you will find a utility call xclusive to circumvent this, and it works great! Now, as the author here noted, if you just want to drag files over, you should be good to go!! Naturally, the lock problem isn’t a problem on first mount since there are no partitions on the card to “lock” (i.e. when you create partitions in the VM for the first time, “you own the lock”). But, ya, on subsequent mounts of the CF card, Windows will lock the partition!!


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