NEC PD754144 User Manual page 208

(4) Executing pending interrupt - interrupt input while interrupts are disabled -
<1> The request flag is held pending even if INT0 is set while the interrupts are disabled.
<2> INT0 servicing program is started when the interrupts are enabled by the EI instruction.
<3> Same as <1>.
<4> INTT0 servicing program is started when the pending INTT0 is enabled.
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CHAPTER 7 INTERRUPT AND TEST FUNCTIONS
<Main program>
Reset
EI IE0
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<1> INT0
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<2> EI
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<4> EI IET0
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User's Manual U10676EJ3V0UM
<lNT0 servicing program>
<3> INTT0
RETI
<lNTT0 servicing program>
RETI