BIOS or EFI is the earliest one in the boot sequence of a typical x86 or x86-64 Linux computer
Step-by-step explanation:
The BIOS-based boot process for x86 and x86-64 architectures is considered to begin when the master boot record (MBR) code is performed in real mode and the first-stage boot loader is placed. BIOS attains for Basic Input/Output System. Displays some system integrity checks.
Searches, loads, and executes the boot loader program. It looks for boot loader in floppy, cd-rom, or hard drive. You can press a key (typically F12 of F2, but it depends on your system) during the BIOS startup to change the boot sequence.