käynnistysprosessiin

Käynnistysprosessiin, commonly referred to as the boot process, is the sequence of operations that a computer performs when it is turned on. This process loads the operating system into memory, making the computer ready for use. The exact steps can vary slightly depending on the computer's hardware and the operating system installed, but the general flow is consistent.

When a computer is powered on, the central processing unit (CPU) begins by executing instructions from a special firmware called the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface), which is stored on a chip on the motherboard. The firmware performs a Power-On Self-Test (POST) to check that essential hardware components, such as the RAM, CPU, and graphics card, are functioning correctly.

Following a successful POST, the firmware identifies the boot device, which is typically a hard drive, SSD, or USB drive, where the operating system is stored. It then loads the bootloader from the boot sector of the boot device into memory. The bootloader is a small program responsible for loading the operating system kernel.

Once the bootloader has loaded the kernel, it hands over control to the operating system. The kernel then initializes various system services, loads necessary drivers for hardware devices, and starts the user interface. Finally, the operating system is fully loaded, and the computer is ready for the user to interact with. This entire sequence, from pressing the power button to seeing the desktop, constitutes the käynnistysprosessi.