A system's BIOS, or Basic Input/Output System, is a software chip in a computer's motherboard that determines how the operating system functions. All Windows operating systems use BIOS, while MacBook computers use an equivalent called EFI, or Extensible Firmware Interface. EFI serves the same purpose as BIOS, where advanced users can configure specific system-level settings. Proceed with caution when accessing this utility, since an error in configuration could jeopardize the stability or functionality on your system.
Shut down your MacBook.
Power on your MacBook after it has completely turned off.
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Press "Command," "Option" and the letters "O" and "F" simultaneously before the system starts up.
Hold the keys until a prompt screen launches. You have accessed the MacBook's BIOS equivalent.