@chicken: I've added precompiled bootloader images to the github repo.
@igor: Thanks for the helpful suggestions.
I agree that the code isn't very polished, will try to fix it up, get rid of magic numbers.
To be honest, I didn't put much thought into that filesystem image. I've created it by making a 512kB file, formatting it to FAT12 with 512b sectors using mkfs.msdos, mounting it and adding a firmware.bin file of the right size.
According to FAT documentation, f0 means a 1.44MB/2.88MB floppy.
Like you said, it's just cosmetic, I didn't bother with it