NEC UPD703116 User Manual page 171

CHAPTER 7 INTERRUPT/EXCEPTION PROCESSING FUNCTION
Figure 7-7. Example of Servicing Interrupt Requests Generated Simultaneously
Main routine
EI
Interrupt request a (level 2)
Interrupt request b (level 1)
Interrupt request c (level 1)
Default priority
a > b > c
Caution The values of the EIPC and EIPSW registers must be saved before executing multiple
interrupts. When returning from multiple interrupt servicing, restore the values of EIPC and
EIPSW after executing the DI instruction.
Remark a to c in the figure are the temporary names of interrupt requests shown for the sake of explanation.
Servicing of interrupt request b
Servicing of interrupt request c
Servicing of interrupt request a
User's Manual U14492EJ5V0UD
.
Interrupt requests b and c are
acknowledged first according to
.
their priorities.
Because the priorities of b and c are
the same, b is acknowledged first
according to the default priority.
171