Q. Define Interrupt Processing?

On completion of execution of an instruction machine checks whether there is any pending interrupt request for interrupts which are enabled. If an enabled interrupt has occurred then that Interrupt can be processed. The nature of interrupt differs from machine to machine. Though let's discuss one simple example of interrupt processing events. A general sequence of steps followed in interrupt stage is:

After completing above interrupt processing, CPU will fetch subsequent instruction which may be interrupt service program instruction. So during this time CPU may be doing the interrupt processing or executing user program. Please note every instruction of interrupt service program is executed just like an instruction in an instruction cycle.