Hi all, I have a question about MAME timers that really gives me a headache From what I see a timer, "advances" when a CPU eats cycles (so it's CPU dependant).
Well, let's take a case with a single CPU (eg. M6809) and with only one IRQ source (for example a vblank IRQ fired by a timer)... So, if the CPU is in "wait mode" (eg: CWAI instruction) and therefore it can be "unlocked" only by the vblank irq..., then 'who' increases the timer that should fire the vblank irq?
|