Almost every game starts its code by doing SEI CLD, but let's assume we have such simple program like that:1. Assuming that the cartridge does not have any chip that pulls /IRQ low, will the program still jump to irq vector eventually, as the source of IRQ can be also internal (APU DMC, APU frame counter)?
2. If the IRQ handler is just RTI, without any code that acknowledges the pending interrupt, assuming that the internal interrupt source is still pending, will the program execute at least one opcode of the regular code after returning from interrupt handler, or will it fetch irq vector immediatelly after doing rti?
Code:
.SEGMENT "CODE"STARTUP = resetreset:jmp resetnmi:rtiirq:rti.SEGMENT "VECTORS".word nmi.word reset.word irq2. If the IRQ handler is just RTI, without any code that acknowledges the pending interrupt, assuming that the internal interrupt source is still pending, will the program execute at least one opcode of the regular code after returning from interrupt handler, or will it fetch irq vector immediatelly after doing rti?
Statistics: Posted by krzysiobal — Sun Jul 07, 2024 1:55 am — Replies 2 — Views 80