NEC PD75402A - Manual (Page 145)

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CHAPTER 6. INTERRUPT FUNCTIONS
6.4 INTERRUPT SEQUENCE
When an interrupt is generated, it is serviced by the procedure shown in Fig. 6-8.
Fig. 6-8 Interrupt Servicing Procedure
Interrupt (INT
×××
) generation
IExxx set?
NO
NO
NO
IRQxxx set
YES
Corresponding VRQn
generation
YES
YES
IST0=0
IME=1
Save PC and PSW contents to stack memory; place data in vector table corresponding
to initiated VRQn into PC.
Change IST0 contents to 1
Reset (0) acknowledged IRQxxx
Branch to start address of interrupt service program proccessing
Hold pending until
IExxx is set
Hold pending
until IME is set
Hold pending until
end of processing
in execution