During startup, which system is primarily responsible for loading the operating system?

The BIOS (Basic Input/Output System) is primarily responsible for loading the operating system during the startup process. When a computer is powered on, the BIOS performs a series of tasks known as the Power-On Self-Test (POST), which checks for hardware components and ensures they are functioning properly. Once POST is complete, the BIOS locates the bootable device, typically the hard drive or SSD, and initiates the process to load the operating system from that device into RAM.

This action is crucial because the BIOS serves as an interface between the hardware and the operating system. It provides the necessary instructions to boot the system and prepares the environment for the OS to take over operations. The BIOS also manages and configures the system settings, which can influence how the operating system is loaded.

While the CPU processes instructions and executes commands, it's the BIOS that orchestrates the initial steps to load the operating system. RAM temporarily stores data for quick access during operation, but does not load the operating system by itself. The GPU, on the other hand, handles graphics rendering and is not involved in the OS startup process.