Oracle provides official VirtualBox personal package archive (PPA) to install it in Ubuntu 16.04. The PPA is provided from VirtualBox own server, not from Launchpad. This PPA in the time we write this article, has latest VirtualBox version 5.0.18. Here the procedures shown step by step.

After years, people doesn't use Disk Operating System (DOS) anymore. Among many DOS systems ever available, MS-DOS was the most popular for desktop computers. But probably for some purposes such learning the basic of Windows command system, learning to install an OS with many disk series (and how to do it later on Debian), playing old DOS games, or any other learning purpose, you will need MS-DOS again. But MS-DOS was proprietary and was abandoned by Microsoft. Don't worry, free software community has created FreeDOS as 1:1 replacement for MS-DOS. FreeDOS was licensed with GNU GPL v2 and available freely. It's almost 100% compatible with MS-DOS internally (to help install some Windows systems) or externally (to install many MS-DOS games or programs). Now, we want to share how to install FreeDOS in Virtualbox. We use Ubuntu as host.

When you run VirtualBox at the first time on Ubuntu 11.10 Oneiric Ocelot, you may get this following error message: "Failed to access the USB subsystem. VirtualBox is not currently allowed to access USB devices. You can change this by adding your user to the 'vboxusers' group. Please see the user manual for more detailed explanation."

VirtualBox is a virtualization application that can help you run any x86 and AMD64/Intel64 compatible operating system on host machine. VirtualBox runs on Windows, Linux, Macintosh, and Solaris hosts and supports a lot of guest operating systems such as (not limited to) Windows NT 4.0, 2000, XP, Server 2003, Vista, Windows 7, DOS/Windows 3.x, Linux (2.4 and 2.6), Solaris and OpenSolaris, OS/2, and OpenBSD. VirtualBox 4.1.4 is now available for Ubuntu 11.10 Oneiric Ocelot.