MC68HC912B32 Datasheet, PDF (56/128 Pages) Motorola, Inc – 16-Bit Microcontroller

After the CCR is stacked, the I bit (and the X bit, if an XIRQ interrupt service request is pending) is set
to prevent other interrupts from disrupting the interrupt service routine. The interrupt vector for the high-
est priority source that was pending at the beginning of the interrupt sequence is fetched, and execution
continues at the referenced location. At the end of the interrupt service routine, an RTI instruction re-
stores the content of all registers from information on the stack, and normal program execution re-
sumes. If another interrupt is pending at the end of an interrupt service routine, the register unstacking
and restacking is bypassed and the vector of the pending interrupt is fetched.
MOTOROLA
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MC68HC912B32
MC68HC912B32TS/D