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IBM nec pd78081(a) User Manual

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183
CHAPTER 12   INTERRUPT FUNCTION
Figure 12-10.  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 
➀
1 Instruction
Execution
NMI Request 
➁
NMI Request 
➀
 Execute
NMI Request 
➁
 
Reserve
Reserved NMI Request Processing
Main Routine
NMI Request 
➀
1 Instruction
Execution
NMI
Request 
➁
NMI Request 
➀
 Execute
NMI Request 
➁
 Reserve
NMI Request 
➂
 Reserve
Reserved NMI Request 
➁
 
Processing
Cannot acknowledge NMI Request 
➂
(Although multiple NMI requests may
be generated twice or more, they
can only be acknowledged once.)
NMI
Request 
➂