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Installing FreeDOS in 86Box: a step-by-step guide

Blog article by MrFlibble

86Box with FreeDOS offer an interesting alternative to DOSBox. 86Box accurately emulates x86 hardware, which may provide advantages when running certain games at a consistent speed or without glitches. Since I found no useful guide for installing FreeDOS in 86Box, I had to figure it out myself. It's generally a very simple procedure, but there are a few not very intuitive steps that you need to take in order for the installation to work.

Please note that this guide applies to the current versions of 86Box (4.0.1, build 5111) and FreeDOS (1.3) as of the time of writing. Future revisions of either may introduce changes that will make this guide less accurate. The guide was written for the Windows version of 86Box, but the procedure on other supported platforms should be the same.

0. Preparing for installation

You will need the following:

An older video guide that I found suggested using the floppy version of FreeDOS, but even though I was able to install it in 86Box, it did not really work as intended.

Set up 86Box for work as follows:

  • Install 86Box if you downloaded the installer, or unpack it wherever you want if you got the portable version.
  • Unpack the contents of the ROM archive into a sub-directory called roms in the directory where the 86Box binary executable is located. More info on the ROM set can be found here.
  • Unzip the FreeDOS LiveCD wherever you can easily access it.

You're now ready to start the FreeDOS installation. Start 86Box to proceed to the next step.

1. Configuring 86Box

By default, 86Box starts as a 8088 PC without any peripherals. For the purpose of this guide, we will configure a 486DX2 machine, which is suitable for running many DOS games from the 90s.

Open the settings menu (Tools -> Settings...).

I have used this Reddit post as guidelines for the combination of machine type, machine and CPU type:

For Display, I picked [VLB] S3 Trio64 (Phoenix). You can try other graphics cards here, it won't affect FreeDOS installation.

On the Input devices tab, select Standard PS/2 Mouse.

For Sound, I selected a Sound Blaster 16 and System MIDI, without changing any settings:

Feel free to experiment with MIDI emulation, there are several interesting options there.

Next, you can skip right to Hard disks. You will need to create a new one. The virtual disk will be stored as a single file, save it wherever you will (e.g. in the base 86Box directory). Pick a size (I selected one of the custom presets), all other options can be left alone for now:

Next is Floppy & CD-ROM drives. You need to configure both. The floppy drive A: must be set to 3.5" 1.44M to be able to read the FreeDOS boot floppy. The CD-ROM drive may be set to anything you like, I set it to ATAPI 16x speed, changing no other settings:

With this, you're set to run the emulated 486 PC. Click OK, and 86Box will restart, applying the new configuration.

2. Installing FreeDOS

While the 486 machine is booting, on the BIOS startup screen, quickly hit Del to enter BIOS options. Select BIOS FEATURES SETUP and make sure that the boot order places the floppy drive (A) first -- otherwise the installation will not continue once the virtual HDD has been partitioned:

If the boot order is C,A, change it to A,C as shown above by pressing the PgUp key. Save and exit BIOS setup.

You will be then greeted with the following message:


Now is the time to mount both the FreeDOS boot floppy and the LiveCD image. Do this via the Media menu. Once done, press Enter.

The LiveCD will boot and present you with the user interface. Select your language and then choose to continue with installation.

It will then ask if you want to partition drive C:, to which you should answer Yes. After that, select the option to reboot the virtual PC.

If the LiveCD does not load after rebooting, double-check if you set the correct boot order in BIOS (see above).

After reboot, FreeDOS will ask if you want to format drive C: and to overwrite the MBR, to which you need to answer Yes as well.

After that, the installation programme will present you with FreeDOS installation options. I selected Plain DOS system, but you can also go for the full install with useful applications and games (but it will take a while to install).

Whichever you choose, the installation will proceed automatically at this point. Once completed, it will prompt you to reboot the machine. Don't forget to eject both the boot floppy and the LiveCD before doing so. If the installation was successful, FreeDOS will boot at next startup.

3. Post-install fix

Once installed, FreeDOS is ready to work out of the box. However, there is a little quirk that in 86Box, it does not correctly identify a 486 machine and thus will not load some of the drivers, such as the CD-ROM and mouse drivers.

To fix this, you will need to edit FreeDOS' AUTOEXEC.BAT. Once the system has loaded, type auto at the DOS prompt. This will open FDAUTO.BAT (which is the FreeDOS version of AUTOEXEC.BAT) for editing.

You will need to find the following line (shown on the screenshot above):

if errorlevel 3 goto Support386

Comment it out by appending rem at the beginning of the line and put this one instead (or just replace 3 with 1 in the above line):

rem if errorlevel 3 goto Support386
if errorlevel 1 goto Support386

Save FDAUTO.BAT and exit the FreeDOS text editor (Alt+X). You can type reboot at the command prompt to reboot the virtual PC from FreeDOS. Next time you boot, the CD-ROM and mouse drivers should load properly.


After playing around with 86box for a while, I noticed that mouse pointer movement is exceedingly rapid, which at first I tried to fix by lowering mouse sensitivity in 86box preferences, but it did not help much. After unsuccessfully trying out different DOS mouse drivers, none of which worked well, I figured out the cause. FreeDOS uses the CuteMouse driver, and for some reason by default it doubles the mouse pointer movement speed, which gets very noticeable in low resolution DOS games. To fix this, you need to manually set the speed by adding the /R command line argument (resolution) to FDAUTO.BAT.

Type auto from the command prompt to edit FDAUTO.BAT, then find the instance of CTMOUSE right after :NoLFN, like this:


Add the argument /R1 after CTMOUSE:


Then save FDAUTO.BAT and reboot.

You can also set the resolution to a value greater than 1, e.g. CTMOUSE /R2. This should make moving the pointer over longer distances across the screen faster, while keeping small movements at the default speed, allowing for better precision. But this may not work well with all games.

86Box has a very useful feature of loading external folders on your PC as CD-ROM images. This way, you can quickly transfer files to the virtual HDD to be used under FreeDOS. However, please take note that when the files are copied, they will retain their read-only attribute (because all files on a CD-ROM drive are normally read-only), which is advised to be removed.