Full screen legacy Dos app in VirtualBox

Rather than running XP in a VM to run a DOS app, why don't you just use DOSBox instead? Most DOS software runs better inside DOSBox than via a VM. The megabuild version (3rd link) adds some features that make it easier to print from DOSBox and adds networking support:

http://portableapps.com/
http://portableapps.com/apps/games/dosbox_portable

http://home.arcor.de/h-a-l-9000/megabuild.html

Check if there is a pif file for your DOS application. Those pif files usually contain information of how to display the app. Sometimes you can also set some of the settings via right clicking the icon and selecting properties.

See if DOSBox works for you. For DOS 6.3 in a Virtual Machine, it cannot be made bigger (full screen) because it is running at its maximum 640x480 resolution.  Even if you display full screen, it only shows a small window in the display.

DOSBox may be OK but be aware that if the DOS application is multi-user or uses record locking it will not work properly.

Compuit1,

I haven't tested this but... Have you checked the VirtualBox Scaling Mode under menu Machine?
In addition, you may need another adjustment via https://www.kirsle.net/blog/entry/virtualbox-scale-mode. Under post "For the Windows users out there..."

OK should of mentioned this, prior to my post I installed DosBox in the VM as well. My initial testing showed DosBox also reduced to a small window on the VM. I think this Dos app is a little more complex too as it communicates with a pervasive database running in the XP environment, hence the need to maintain the whole Windows XP system / realm as a unit. I understand the database software is not supported on Win 8 / 10.  

If the database software could run on the Win 8 system would the thinking be to then install DosBox directly onto the the Win 8 system, then install the dos app to DosBox which will then communicate with the Database app running on the 64bit Win 8 host?

Try this:
Make sure the DOS application has focus.
Press Alt+Enter.
This should return the DOS app to a window.
Then click on the top left corner of the window and select properties.
From there you can experiment with setting such as font sizes.

Hi Rindi, Thank you  - Yes I have tried different setting on the shortcut with varying results all which appear to be worse than the default. I will check for a pif file.

Thank you for the comments. AKB I did try this and the result is similar to modifying the shortcut properties. No solution really. Right I could not find a "PIF" file in this instance to modify - However the symptom is exactly the same as creating a shortcut to the windows command prompt on the VM's desktop, then setting the shortcut to run the cmd screen in "full screen mode". The VM screen shrinks to the size of the CMD screen. This is not to bad an idea if the shrunk screen is readable. I think maybe we should look at what VirtualBox is doing and attempt to see if we can lock in the displays aspect ratio?

Hello people - Thank you for the input however we are not successful. I think it is in the too hard basket. From what has been pointed out... Having DosBox installed on the host will most likely work but will not be able to get the database functional which will render the scheme ineffective.

Did you try the console from sourceforge?

Guys the situation is pretty bleak - there is no installation media and there appears to be some windows back end dependency stuff. The system had to be captured in its entirety. Points for contribution granted.