NEC PD17062 User Manual
Page 127
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127
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PD17062
Fig. 11-7 Interrupt Stack Operation at Multiple Interrupts
(a) Multiple level-2 interrupts
(b) Multiple level-3 interrupts
MAIN
A
MAIN
B
A
MAIN
RETI
RETI
A
MAIN
MAIN
MAIN
MAIN
MAIN
Interrupt B
Interrupt
stack
Undefined
Main routine
Interrupt A
Interrupt
stack
Undefined
Undefined
MAIN
A
MAIN
B
A
C
B
A
MAIN
B
A
A
A
RETI
RETI
RETI
A
A
A
A
If control is returned to the main routine at this time,
BANK and IXE of interrupt A are restored and the
main routine operates abnormally.
Undefined
Undefined
Main routine
Interrupt A
Interrupt B
Interrupt C
Undefined
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