peruskäynnistys

Peruskäynnistys, known in English as basic startup or cold boot, refers to the process by which a computer system initializes from a completely powered-off state. This is distinct from a warm boot or restart, where the system is already running and undergoes a reboot process. During a peruskäynnistys, the central processing unit (CPU) executes a predefined sequence of instructions to bring the system to an operational state. This sequence typically begins with the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface) firmware, which is stored in non-volatile memory on the motherboard.

The firmware performs a Power-On Self-Test (POST) to check that essential hardware components, such as the CPU, RAM, and graphics card, are functioning correctly. If POST is successful, the firmware then identifies and loads the operating system's bootloader from a designated storage device, commonly a hard drive or SSD. The bootloader is a small program responsible for initiating the loading of the main operating system kernel into memory. Once the kernel is loaded and initialized, it takes control of the system, loads necessary drivers, and starts the user interface or command-line environment, ultimately making the computer ready for user interaction.