NEC PD78F9488 Manuale Utente

CHAPTER  16   INTERRUPT  FUNCTIONS 

 

User’s Manual  U15331EJ4V1UD 

The non-maskable interrupt request is unconditionally acknowledged even when interrupts are disabled.  It is not 

subject to interrupt priority control and takes precedence over all other interrupts. 

When the non-maskable interrupt request is acknowledged, the PSW and PC are saved to the stack in that order, 

the IE flag is reset to 0, the contents of the vector table are loaded to the PC, and then program execution branches. 

Figure 16-10 shows the flow from non-maskable interrupt request generation to acknowledgment, Figure 16-11 

shows the timing of non-maskable interrupt acknowledgment, and Figure 16-12 shows the acknowledgment operation 
when a number of non-maskable interrupts are generated. 

 
Caution  During non-maskable interrupt service program execution, do not input another non-maskable