This is a translation with minor changes from the original post according to advice from comments.
Hello, folks! We have studied the boot sequence of the Windows operating system as part of a project from Acronis with students of Innopolis University. You can find more about the project here and there. There was an idea to execute the logic even before the boot sequence of the OS. Therefore, we tried to write something just to try, for a smooth immersion in UEFI. In this article, we will go through the theory and practice to read and write to disk in a pre-OS environment.