Käivituslaadur

A käivituslaadur, also known as a bootloader, is a special program that runs when a computer or device is first turned on. Its primary purpose is to initialize the hardware and then load the operating system or another program into memory. Without a käivituslaadur, the system wouldn't know how to start the main software it needs to function.

The käivituslaadur performs several crucial tasks. First, it performs a Power-On Self-Test (POST) to check if the essential hardware components, such as the CPU, memory, and graphics card, are working correctly. If the POST is successful, the käivituslaadur then locates the operating system or the desired application on a storage device like a hard drive or flash memory. It then copies the necessary parts of this software into RAM (Random Access Memory). Once loaded, the käivituslaadur hands over control to the operating system, which then takes over the rest of the startup process.

Different devices and operating systems use various types of käivituslaadurid. For example, on personal computers, the BIOS (Basic Input/Output System) or UEFI (Unified Extensible Firmware Interface) firmware acts as the initial käivituslaadur. These firmware programs then load a bootloader specific to the installed operating system, such as GRUB for Linux or the Windows Boot Manager. In embedded systems and mobile devices, simpler, often custom-made käivituslaadurid are used to load the device's specific operating environment. The security of the käivituslaadur is also critical, as compromised bootloaders can lead to the system being taken over by malicious software.