NEC PD754144 User Manual page 211

(7) Enabling nesting of two interrupts - INTT0 and INT0 are nested doubly and INTBT and INTT2 are nested
singly -
<Main program>
EI IET0
EI IE0
EI IEBT
EI IET2
EI
<1>
<1> When an INTBT that does not enable nesting occurs, the INTBT servicing routine is started. The status
is 1.
<2> The status is changed to 0 by clearing IST0. INTBT and INTT2 that do not enable nesting are disabled.
<3> When an INTT0 that enables nesting occurs, nesting is executed. The status is changed to 1, and all
interrupts are disabled.
<4> The status is returned to 1 when INTT0 servicing is completed.
<5> The disabled INTBT and INTT2 are enabled, and execution returns to the main routine.
CHAPTER 7 INTERRUPT AND TEST FUNCTIONS
Reset
Status 0
INTBT
Status 0
<3> INTT0
User's Manual U10676EJ3V0UM
<lNTBT servicing program>
<2> DI
Status 1
CLR1 IST0
DI IEBT
DI IET2
Status 0
EI
<lNTT0 servicing program>
<4>
Status 0
<5> EI IEBT
EI IET2
RETI
Status 1
RETI
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