NEC uPD78P078 - Manual (Page 521)

521
CHAPTER 22 INTERRUPT FUNCTIONS
Figure 22-16. Multiple Interrupt Example (2/2)
Example 3. A multiple interrupt is not generated because interrupts are not enabled
Because interrupts are not enabled in interrupt INTxx servicing (an EI instruction is not issued),
interrupt request INTyy is not acknowledged, and a multiple interrupt is not generated. The INTyy
request is reserved and acknowledged after 1 instruction execution of the main processing.
PR = 0 : Higher priority level
IE = 0 : Interrupt request acknowledge disable
Main Processing INTxx
Servicing INTyy
Servicing
INTxx
(PR = 0)
1 Instruction
Execution
IE = 0
INTyy
(PR = 0)
IE = 0
RETI
RETI
EI