NEC PD75402A User Manual page 150

(3) Pending interrupt execution - interrupt input in interrupt disabled state
Although INT0 is set in the interrupt disabled state, the interrupt flag is held pending.
The INT0 service program is started at point at which interrupts are enabled by the EI instruction.
Same as .
The INTCSI service routine is started at the point at which the pending INTCSI is enabled.
4
CHAPTER 6. INTERRUPT FUNCTIONS
<Main program>
Reset
EI IE0
INT0
EI
EI IECSI
<INT0 Service Program>
INTCSI
RETI
<INTCSI Service Program>
RETI
139