UPD17704 Datasheet, PDF (135/356 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DEDICATED HARDWARE FOR DIGITAL TUNING SYSTEM

µPD17704, 17705, 17707, 17708, 17709
12.3.3 Interrupt stack operation
Figure 12-8 shows the operation of the interrupt stack.
When nested interrupts exceeding four levels are accepted, since the contents saved first are discarded they
therefore must be saved by the program.
Figure 12-18. Operation of Interrupt Stack (1/2)
(a) Where interrupt nesting level is 4 or less
Undefined
Undefined
Undefined
Undefined
Main routine
MAIN
MAIN
Undefined
Undefined
Undefined
Interrupt A
A
A
MAIN
Undefined
Undefined
Interrupt B
B
Undefined
Undefined
Undefined
Undefined
RETI
MAIN
Undefined
Undefined
Undefined
RETI
A
MAIN
Undefined
Undefined
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