NEC 78K0 Series User Manual page 504

Example 3. Multiple interrupt servicing does not occur because interrupts are not enabled
Interrupts are not enabled during servicing of interrupt INTxx (EI instruction is not issued), therefore, interrupt
request INTyy is not acknowledged and multiple interrupt servicing does not take place. The INTyy interrupt request
is held pending, and is acknowledged following execution of one main processing instruction.
PR = 0: Higher priority level
IE = 0: Interrupt request acknowledgement disabled
504
CHAPTER 19 INTERRUPT FUNCTIONS
Figure 19-10. Examples of Multiple Interrupt Servicing (2/2)
Main processing
IE = 0
EI
INTxx
(PR = 0)
IE = 1
1 instruction execution
Preliminary User's Manual U17260EJ3V1UD
INTxx servicing INTyy servicing
INTyy
(PR = 0)
RETI
IE = 0
RETI
IE = 1