Installing FreeDOS
After putting the install CD (you can get the ISO from freedos.org, floppy install is also provided) and booting the PC from it, we get this bootloader menu:
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We're installing the system to disk, so let's pick "Install to harddisk".
The installer warns us about the risk of overwriting other systems and asks if we want to continue:
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Despite the warning the installer won't overwrite any parttions or MBR unprompted, so let's continue.
After continuing, the installer asks for the keyboard layout and if it should overwrite the MBR:
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Here we pick "No" - we want to keep the Windows bootloader, instead of using the FreeDOS one, which can only boot DOS. We'll configure the computer to allow selecting 3 systems later.
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Now we can select if we want a minimal install or something more. I'm picking a full install, which comes with a good amount of open-source DOS software and still takes less than 512 MB. It even lets us install all the source code to experiment around with, but I decided to only install the binaries for now.
The installer starts copying files, showing a progress bar:
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After waiting for copying to finish, we can remove the install CD and reboot. We won't be able to boot our DOS install yet - to do that, we have to add it to the boot menu, much like we did with OpenBSD in part 2.
Can NTLDR boot FreeDOS?
NTLDR is the bootloader of Windows XP. It's quite flexible and can boot both Windows and other systems - the latter mostly by loading their own bootloaders. That's how we got OpenBSD to dual boot in part 2 - NTLDR loads the OpenBSD bootloader from the file OPENBSD.PBR.
I tried to do the same with the FreeDOS bootloader, which wasn't succsesful, as the FreeDOS bootloader failed to find the DOS partition when started from NTLDR.
Luckily, I found a working solution to multi-boot NTLDR systems like Windows XP and FreeDOS - using a more advanced bootloader to correctly tell the FreeDOS bootloader where the system is located. The advanced bootloader we'll be using is GRUB4DOS.