käynnistystoimintosarja

Käynnistystoimintosarja, often referred to as the boot sequence, is the series of operations a computer performs when it is first turned on or reset. This process loads the operating system into the computer's memory, making it ready for use. The sequence begins with the Power-On Self-Test (POST), a diagnostic check of the hardware components. Once POST is successfully completed, the system firmware, typically the BIOS or UEFI, takes over.

The firmware's primary role is to locate and initialize essential hardware devices such as the CPU, memory, and storage controllers. It then reads the boot loader from a designated storage device, which is usually the hard drive or SSD. The boot loader is a small program responsible for loading the main operating system kernel. After the kernel is loaded into memory, it initializes the rest of the operating system, including device drivers, system services, and the user interface. This entire process ensures that all necessary software and hardware are ready before the user can interact with the computer. The specific steps and the order in which they occur can vary slightly depending on the computer's hardware and the operating system installed.