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CHAPTER 6 INTERRUPT AND TEST FUNCTIONS
(7) Enabling of level-two interrupts (enabling level-two INTT0 and INT0 interrupts with INTCSI and INT4handled as level-one interrupts)<1> When an INTCSI interrupt not allowed to be a level-two interrupt occurs, the INTCSI service programstarts, and status 1 is set.<2> Status 0 is set by clearing IST0. INTCSI and INT4 not allowed to be level-two interrupts are disabled.<3> When INTT0 allowed to be a level-two interrupt occurs, the level-two interrupt is executed, and status1 is set to disable all interrupts.<4> When INTT0 processing is completed, status 0 is set again.<5> INTCSI and INT4 which have been disabled are enabled, then control returns.

Reset

<INTCSI service program>

EI IET0

<Main program>

EI IE0

EI IECSI Status 0

Status 0
Status 0

Status 1

Status 0

Status 1

<3> INTT0

<2> DI

CLR1 IST0

DI IECSI

DI IE4

EI <INTT0 service program>

<4> RETI

EI IECSI

EI IE4

RETI

<5>

<1> INTCSI

EI IE4

EI

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