Where are the instructions to start the computer system stored?

The instructions to start the computer system, commonly referred to as the boot process, are stored in the BIOS (Basic Input/Output System). The BIOS is a firmware that resides on a chip on the motherboard, and it is the first software that runs when a computer is powered on. Its primary role is to initialize hardware components and to load the operating system from the storage device into RAM.

When the computer is powered up, the BIOS performs a series of checks, known as the POST (Power-On Self-Test), to ensure that all the key hardware components are functioning correctly. Once these checks are complete, the BIOS uses the boot loader to find and start the operating system, allowing the computer to run user applications.

The functionality of each of the other components further supports this process but does not include the actual storage of boot instructions. For example, RAM is temporary storage for data currently in use; the CPU executes instructions but does not store them; and while the motherboard provides connectivity to various components, it does not store system start instructions either. Therefore, the BIOS plays a critical and irreplaceable role in the system's startup process.