NEC PD754144 - Manual (Page 211)

CHAPTER 7 INTERRUPT AND TEST FUNCTIONS
211 User’s Manual U10676EJ3V0UM
(7) Enabling nesting of two interrupts - INTT0 and INT0 are nested doubly and INTBT and INTT2 are nested
singly -
Reset
INTBT <1>
EI
EI
EI
EI
EI
IET0
IE0
IEBT
IET2
Status 0
Status 0
Status 0
Status 1
INTT0 <3>
RETI <4>
Status 1
Status 0
EI
EI
RETI
<5> IEBT
IET2
DI
CLR1
DI
DI
EI
<2>
IST0
IEBT
IET2
<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.