NEC mPD780852 Series Preliminary User's Manual page 260

Example 3. Multiple interrupt servicing does not occur because interrupt is not enabled
Interrupt is 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 acknowledge disable
260
CHAPTER 19 INTERRUPT FUNCTIONS
Figure 19-14. Multiple Interrupt Examples (2/2)
Main processing
IE = 0
EI
INTyy
(PR = 0)
INTxx
(PR = 0)
1 instruction execution
Preliminary User's Manual U14581EJ3V0UM00
INTxx servicing INTyy servicing
RETI
IE = 0
RETI