In a typical computer, what is the correct sequence from power-on to the operating system load?

In a typical computer, what is the correct sequence from power-on to the operating system load?

• A. POST runs, BIOS/UEFI initializes hardware, bootloader loads OS
• B. BIOS initializes hardware, POST runs, bootloader loads OS
• C. Bootloader loads OS after hardware initialization
• D. POST loads OS

Answer: (A)

When power is applied, the firmware starts by running a POST, a quick self-test that checks essential hardware like memory and CPU to make sure everything basic is functioning. If POST passes, the firmware (BIOS or UEFI) moves on to initialize and configure the rest of the hardware, set up devices and memory mappings, and select a boot device. From that device, a bootloader is loaded. The bootloader is a small program whose job is to load the operating system kernel into memory and hand control over to it. Once the kernel starts, the operating system completes its own initialization and brings the system to a usable state. This flow—POST, hardware initialization by the firmware, then bootloader loading the OS—is why the correct answer lists POST first, then hardware initialization, then the bootloader loading the OS.

When power is applied, the firmware starts by running a POST, a quick self-test that checks essential hardware like memory and CPU to make sure everything basic is functioning. If POST passes, the firmware (BIOS or UEFI) moves on to initialize and configure the rest of the hardware, set up devices and memory mappings, and select a boot device. From that device, a bootloader is loaded. The bootloader is a small program whose job is to load the operating system kernel into memory and hand control over to it. Once the kernel starts, the operating system completes its own initialization and brings the system to a usable state. This flow—POST, hardware initialization by the firmware, then bootloader loading the OS—is why the correct answer lists POST first, then hardware initialization, then the bootloader loading the OS.