What is the role of startup BIOS in a computer system?

The startup BIOS, or Basic Input/Output System, plays a crucial role in controlling the PC during the boot-up process. When a computer is powered on, the BIOS is the first software that runs. It initializes and tests hardware components, such as the CPU, RAM, and storage devices, and ensures that everything is functioning correctly. This process is known as the Power-On Self-Test (POST).

Once the BIOS has conducted the necessary checks, it locates the operating system stored on the hard drive or another bootable device and hands over control to that operating system, allowing the computer to proceed with loading the software. This function underscores the importance of the BIOS in preparing the system for use and ensuring that all components are ready for operation.

In contrast, the other options relate to functions that are not specifically performed by the BIOS. For example, managing system power supply typically falls under the purview of power management systems and not the BIOS itself. Similarly, controlling network connections is handled by network interface controllers or operating system drivers. The function of storing data on the hard drive is managed by the hard drive and the operating system, rather than the BIOS.