The p-Code Machine

A few days ago I’d been fiddling with creating a FreeDOS bootable USB stick, with little succes actually… But there’s an easy way which works on all operating systems which run qemu, I’ll be focussing on Ubuntu Linux.

First download the Balder FreeDOS floppy, and save it somewhere convenient on your disk. Then connect your USB stick to your system, make sure you unmount the stick’s filesystems before proceeding:

# sudo umount /media/usbstick

Then wipe the USB stick using dd to make sure it’s completely clean. This step is not really required, but this does make sure you won’t run into any other problems later on. Make sure you know you have the correct device file, making a mistake with this can really screw up your Ubuntu install, as an example I’ll be using sdu:

# sudo dd if=/dev/zero of=/dev/sdu bs=1M

Then we start qemu booting from the Balder boot floppy image:

# sudo qemu -fda balder10.img -hda /dev/sdu -boot a

If all goes well you’ll see FreeDOS booting from the floppy drive.

A:\>fdisk

Then partition a single large volume, the following should have the same effect:

A:\>fdisk /auto C:

Then format the partition and copy system files:

A:\>format C: /V:FREEDOS /S

Then you can copy any other DOS utilities you might need from the Balder image to the C: drive, which in essence is your USB stick. Then close qemu. Then we can verify if the stick boots properly like so:

# sudo qemu -hda /dev/sdu -boot c

If you want to place some extra files on there like a BIOS flash utility and a BIOS upgrade file you issue the eject command, and then disconnect and reconnect the USB stick:

# sudo eject /dev/sdu

I hope this works for you as well. Good luck and be careful!