GMS81004 Datasheet, PDF (71/101 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCOMPUTERS

Chapter 5. Interrupt
5.4 INTERRUPT PROCESSING SEQUENCE
When an interrupt is accepted, the on-going process is stopped and the interrupt service
routine is executed. After the interrupt service routine is completed it is necessary to
restore everything to the state before the interrupt occured.
As soon as an interrupt is accepted, the content of the program counter and PSW are
saved in the stack area.
At the same time, the content of the vector address corresponding to the accepted
interrupt, which is in the interrupt vector table, enters into the program counter and
interrupt service is executed. In order to execute the interrupt service routine, it is
necessary to write the jump addresses in the vector table (FFEOH-FFFFH)
corresponding to each interrupt
Interrupt Processing Step
1) Store upper byte of Program Counter, SP ¡ç SP
2) Store lower byte of Program Counter, SP ¡ç SP - 1
3) Store Program Status Word, SP ¡ç SP - 2
4) After resetting of I-flag, clear accepted Interrupt
Request Flag.(Set B-flag for BRK Instruction)
5) Call Interrupt service routine
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