Kernel mode and User mode

Kernel mode In the kernel mode, the executing code has complete and unrestricted access to the underlying hardware. It can execute any CPU instruction and reference any memory address.Kernel mode is generally reserved for the lowest level, most trusted function of operating system.   User mode In user mode, the executing code has no ability ...

Interrupts

An interrupt is a signal to the processor emitted by hardware or software indicating an occurrence of an event that needs immediate attention.The processor responds by suspending its current activities, saving its state, and executing a small program called an interrupt handler (or interrupt service routine, ISR) to deal with the event. This interruption is temporary, and after ...