118 Cloud Computing
grouped in three tabs for the three supported formats. These are hard disk
images, either in VirtualBox’s own Virtual Disk Image (VDI) format or the
widely supported
V
irtual
M
achine
D
is
K
(VMDK) format. CD and DVD
images in standard ISO format are supported. There is support for floppy
images in standard RAW format. As you can see in the figure below, for each
image, the Virtual Disk Manager shows you the full path of the image file
and other information, such as the virtual machine the image is currently
attached to, if any.
Clicking the
Add button will bring you to the Select a hard disk
image file dialog box, as shown below:
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Adding a Guest OS to Sun xVM VirtualBox 119
Using this file dialog, you must navigate to your VirtualGuests folder.
In your VirtualGuests folder, open the VDI folder and highlight the Free-
DOS .vdi file. Once you have it highlighted, simply click on the Open but-
ton. You are returned to the Virtual Hard Disk dialog box, where you
earlier clicked the Existing... button:
Click Next > to complete the addition of the FreeDOS virtual image. A
summary screen, as shown below, will appear:
Here, simply click the Finish button and you will be returned to the
Sun xVM VirtualBox main display. FreeDOS should be displayed in the left
panel (it should be the only entry on your system) similar to the list shown
in the following image:
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120 Cloud Computing
Before we explore the FreeDOS environment, it is a good idea to
check the settings to ensure that the guest system will work the way you
want. The Settings button (in the figure above, it looks like a gear) in the
toolbar at the top of the VirtualBox main window brings up a detailed
window where you can configure many of the properties of the VM that is
currently selected:
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Adding a Guest OS to Sun xVM VirtualBox 121
Click your desired settings—but be careful. Even though it is possible
to change all VM settings after installing a guest operating system, certain
changes after installation may prevent a guest operating system from func-
tioning correctly.
Since you have just created an empty VM, you will probably be most
interested in the settings in the CD/DVD-ROM section if you want to
make a CD-ROM or a DVD-ROM available the first time you start Free-
DOS, so that you can use it with your guest operating system. This will
allow your VM to access the media in your host drive, and you can proceed
to install from there. Check the box in the CD/DVD section if you want to
use an optical device.
For now, that is all you need to do in Settings to prepare to run your
virtual image. The next part of our practicum will take you inside the virtual
guest system to use and and see for yourself that it is a real, functioning
environment. We will show you how to set up a graphical user interface
within the DOS environment using an open source product called Open-
GEM. OpenGEM was modeled after GEM, one of the earliest GUI envi-
ronments widely available on the DOS platform.
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122 Cloud Computing
To start FreeDOS, highlight FreeDOS in the selections panel and click
the green Start arrow as shown below.
When you first start FreeDOS, you are presented with a “Load” menu,
as shown below. Usually, the default selection best for your system is high-
lighted automatically. Choose the default option and press Enter (or just let
the 5-second timer expire).
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