Computer system operating system concept version 6

To start the computer, for example, when the power is on or the computer restarts, it needs to run an initialization program. The initialization program orBootstrap program(Bootstrap program) is relatively simple. It is usually located in read-only memory (ROM), such as firmware or EEPROM in computer hardware. It initializes all parts of the system, from CPU registers, device controllers to memory content. The boot program must know how to mount the operating system. To accomplish this, the boot program must locate the operating system kernel and load it into the memory. Then, the operating system starts to execute the first process, such as init, and waits for some events.

Events usually occur through hardware or software.Interrupted(Interrupt) to indicate that the hardware can signal to the CPU at any time through the system bus to trigger the interruption. By executing a system call (also called system call)Monitor call(Monitor call.