To install a VHD image in VirtualBox:

• Download the zipped VHD-File, f.i. FreeDOS1.2.vhd.zip
• Unzip it.
• Save it to a location of your choice, f.i. in:

  /Users/YourName/VirtualBox VMs/

• Start VirtualBox (I tested this with version 4 and 5).
• Choose “New“.

• Give the new virtual machine a name, f.i. “FreeDOS 1.2”

• Choose 32 MB RAM.
• Choose “Use existing hard disk” and point it to the location of the VHD-file.

• Choose “Finish“.

Your FreeDOS virtual machine is now ready to go – almost.

Additional information

Here is some important information you should know about:

• Prevent DOS from overheating your PC
• Exchanging files with the FreeDOS machine