22 September 2022 Reverse Engineering MenuetOS 64 - Primary Boot Loader Background on Booting There are two types of boot systems in x86/x64 environments: UEFI and BIOS-based. UEFI provides a standard and reference implementation for the code that executes between the CPU being released from reset and the computer transferring execution to code stored on fixed media, such as hard disks and USB drives. The code executes between these two boot stages is located on a dedicated memory chip on the mo...