NEC PD78052 - Non-Maskable Interrupt Request Acknowledge Operation

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CHAPTER 21 INTERRUPT AND TEST FUNCTIONS
Figure 21-12. Non-Maskable Interrupt Request Acknowledge Operation
(a) If a new non-maskable interrupt request is generated during
non-maskable interrupt servicing program execution
(b) If two non-maskable interrupt requests are generated during
non-maskable interrupt servicing program execution
Main Routine
NMI Request <1>
1 Instruction
Execution
NMI Request <1> is executed.
NMI Request <2> is reserved.
Reserved NMI Request <2> is processed.
NMI
Request <2>
Main Routine
NMI Request <1>
1 Instruction
Execution
NMI
Request <2>
NMI Request <1> is executed.
NMI Request <2> is reserved.
NMI Request <3> is reserved.
NMI Request <2> is processed.
NMI
Request <3>
NMI requests <3> is not acknowledged
(only one request has been acknowledged,
even when two or more NMI requests are
generated).