While you're rolling out your new Windows XP SP1 systems to your users, you
might run into an instance where you need an old trusty DOS machine to handle a
specific task. IBM and Microsoft long ago abandoned DOS, so where should you
turn? FreeDOS is your answer. FreeDOS is an open source clone of MS-DOS that can
implement and extend much of the functionality from MS-DOS.
System requirements
When I discuss utilities, I generally like to outline the RAM, disk space, and processor requirements and detail what software prerequisites there are for the topic I'm discussing. I'll bet it's been a while since you heard something like this: FreeDOS requires a PC/XT with 640 KB of RAM.
For the demonstration in this article, I'll be using FreeDOS in a Virtual PC partition on a system with a 1.6-GHz Pentium 4 processor. Additionally, I have tested FreeDOS on other systems running VMWare 4, and it works equally as well under that product.
How is it different from MS-DOS?
While FreeDOS aims to clone the full functionality of MS-DOS, there are some differences between the two programs. Volunteer contributors to the project write each of the utilities included with FreeDOS—for example, edlin and copy. This means that the functionality of the FreeDOS version of a traditional MS-DOS utility may not exactly match that of the MS-DOS version. You don't need to worry about it, though.
The coding standards for the project specify that any programs written must be compatible with MS-DOS 6.22. However, the base kernel for FreeDOS is MS-DOS 3.3. The developers chose that relatively ancient version of DOS because they believed that releases after that didn't add enough functionality to the actual kernel to warrant anything more.
Getting started with FreeDOS
FreeDOS is available for download from the project's Web site. At the time of this writing, there was a problem with the download from the site, so I downloaded it from a mirror site instead. The downloaded file is a 39-MB CD-ROM ISO image that contains the application. To get started, burn this image onto a CD.
The first boot
One of the first things that you will notice is that FreeDOS—like a whole lot of other open source projects—is perpetually in beta. The release that I am using for this example is version 8H1 beta.
The main menu in FreeDOS, shown in Figure A, has five options. The first option—option 0—allows you to just boot from the system drive. The second and third options allow you to boot to a DOS prompt. The difference is this: Option 1 boots with a standard kernel that just supports the FAT file system, while option 2 boots with an experimental DOS kernel that supports the FAT32 file system. The final two options—A and Q—allow you to either boot from the floppy drive or to just skip booting from the CD-ROM and boot from the next BIOS-dictated device. If you don't choose anything after 20 seconds, the system will just boot from the first available hard drive. For this example, I will boot the system using option 1.
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