499CHAPTER 21 INTERRUPT AND TEST FUNCTIONSMain ProcessingEIINTxx(PR=1)INTyy(PR=0)IE=0EIRETIINTxxServicingINTzz(PR=0)IE=0EIRETIINTyyServicingIE=0RETIINTzzServicingFigure 21-16. Multiple Interrupt Example (1/2)Example 1 Example of multiple interrupt requests being generated twice.During processing of interrupt INTxx, 2 interrupt requests, INTyy and INTzz, are received and multipleinterrupts are generated. Before reception of each interrupt request, the IE command must be issuedand the interrupt request reception permitted status must exist.Example 2 Example of multiple interrupts not being generated due to priority order controlDuring processing of interrupt INTxx, interrupt request INTyy was generated, but the priority orderof this interrupt was lower than that of INTxx, so it was not received and multiple interrupts were notgenerated. Interrupt request INTyy was held and received after 1 main processing command wasexecuted.PR = 0 : High Priority Order LevelPR = 1 : Low Priority Order LevelIE = 0 : Interrupt Request Reception ProhibitedMain Processing INTxxServicingINTyyServicingINTxx(PR=0)1 InstructionExecution IE=0INTyy(PR=1)EI IE=0EIRETIRETI
