OSDev.org

Hey guys, it's andrewthompson555. Want to put a bootloader onto a bootable IMG file but want more files in it? Sick and tired of getting many problems with trying to copy your kernel into your USB? You've come to the right place!

Anyway, whoever wants to make their OS work on the BIOS on a USB. This will make a FAT12 image! WARNING! This might stop Windows from letting you get data from the stick. Do 'format /q <USB DRIVE>' if this happens.

1) Download fat_imgen and Rufus
2) Put a BPB (BIOS Parameter Block) into your bootloader
3) Compile it with NASM
4) Put it in with the exe file of fat imgen
5) Do 'fat_imgen -c -f os.img -s boot.bin
6) Open Rufus
7) Select DD Image and your USB drive
8 ) Select the .img file by pressing that button near the create bootable option
9) Press the start and it will make your USB into FAT12 as well
10) Restart your PC and enable F12 boot manager in the BIOS
11) Search for USB FDD (There might be duplicate so try the bottom and top)
12) Kaboom! It's right there.

If you could expand on this somewhat - and either remove references to specific tools, or better yet, write approaches to handling each step using different toolchains (as about half of the devs here don't use Windows as their development host, even if they do use it as their main general-purpose system, and most of those who do use the binutils toolchain via Cygwin anyway) - this would be a useful addition to the wiki, which (on a cursory check) doesn't seem to cover this subject yet.

Note also that using floppy emulation on a USB has fallen out of favor, as most USB flash drives in the past several years are measured in the gigabytes rather then kilobytes, and even those which it was used for have all been too large to use FAT12 to support the full drive capacity. AFAICT, many USB drives of the past five years don't properly support floppy emulation at all. While FAT12 is useful as practice when starting out, I seriously don't recommend using it for most purposes today.