Interrupt Processing Procedure
• Input output device issues the interrupts.
• The Processor finishes the execution of an instruction before responding to the interrupt.
• The Processor checks for an interrupt. If there is one, it then sends an acknowledgement signal to the input output device that issued the interrupt. The signal allows the device to remove its interrupt signal.
• To switch to run interrupt Handler, information about the current program is stored, so that it execution maybe resumed later including Program status word(psw) and program counter(PC).
• The processor loads the program counter with the entry location of the interrupt Handler. Typical case is there are set of routines. Each for one type of interrupt or each for one device.
• The Interrupt Handler may continue to save other information that is considered as part of process state.
• The handler performs the interrupt processing.
• When handler finishes, the saved Register values are stored into the registers that originally hold them when interrupt handler returns.
• Finally PSW and PC values of the interrupted program are restored, thus the program may continue to execute.