Ottawa PC Users' Group, Inc.
 Product Review 


DOS-in-a-Box
by Alan German

Do you have a need - or a desire - to run DOS programs? Perhaps you have some programs that you wrote many moons ago (like my Clipper-compiled, dBASE III, accounting program from 25 years ago!) Or, maybe you have some old games that you haven't played in a while. But, when you go to start these DOS programs on your new computer, running 64-bit Windows 7, you are presented with an error message that your program is an "Unsupported 16-Bit Application". In other words your version of Windows won't run DOS programs.

Well, that's not strictly true. Sure, 64-bit Windows won't run DOS programs natively, but you can work around this limitation by using a virtual machine. For example, you could install Virtualbox on your computer, set up a virtual machine (VM), install DOS on this VM, load your DOS program, and run it inside the VM.

The major downside to this procedure is that you will have to find a copy of DOS to install in the virtual machine. If you can even find such a beast, it's very likely that your copy of DOS will be on 3.5" floppy disks - and your brand spanking new box doesn't have a floppy disk drive!

It turns out that there is a much simpler solution - install and run DOSBox. This software is essentially a dedicated virtual machine for DOS, and you will be able to run your old programs with relative ease.

By default, DOSBox loads with drive Z: enabled. This contains such old favourites as COMMAND.COM and AUTOEXEC.BAT. However, DOSBox is much more useful if we point it to a real disk drive (or partition) by using the mount command. In the screenshot, you can see that I have enabled drive d: in DOSBox as the real drive D: (the data partition) on my hard drive.

Clearly, one can mount any Windows drive in a similar manner. So, for example, we could run a DOS program that is installed (loaded) on either the C: or the D: drive, or mount a CD-ROM and run software directly from the optical disk.

The other trick with DOSBox is that it uses a configuration file (dosbox.conf) stored in the main DOSBox folder (usually C:\Program Files\DOSBox). Multiple entries in this file control, a whole host of program features. I found it particularly useful to change "windowresolution=original" to "windowresolution=1024x768" and "output=surface" to "output=opengl". These modifications enabled a somewhat larger window to be used for the main DOSBox program than that established by default.

Finally, DOS commands added to the last section of the configuration file are run automatically when DOSBox starts. Placing specific commands here can be very useful, for example to mount a disk drive/partition that will be used in subsequent DOS operations.

I have adopted this technique to mount my data disk each time I run DOS Box, and to transfer control to this drive. As you might guess, the commands at the end of the configuration file are:

[autoexec]
# Lines in this section will be run at startup.
mount d d:\
d:

So, there you have it - the possibility of recalling a blast from the past! Run your old DOS programs on your brand spanking new 64-bit Windows computer using DOSBox.


Bottom Line:

DOSBox (Open Source)
Version 0.74
Peter Veenstra, Sjoerd Harekiet, Tommy Frössman and Ulf Wohlers
http://www.dosbox.com/


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Ottawa Personal Computer Users' Group (OPCUG), Inc.
3 Thatcher Street, Ottawa, ON  K2G 1S6

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