I have small problem. I have made very simple bootloader. After it’s creation I created new empty .iso file.
mkisofs -o cd.iso content
Then I used Okteta editor and I filled first 512 bytes with bootloader.

Then I started .iso image in Virtual Box.
My problem is error message:
FATAL: No bootable medium found
Does anybody know how can I make it working? Where have I error?
Please help.
You can’t just copy your floppy/HDD boot sector onto a cd image and expect it to work. To make a bootable cd-rom, you need to abide by the El Torito standard. Here’s a quick guide how to make a bootable cd from a floppy image.