[Coco] auto-starting game paks
Roger Taylor
operator at coco3.com
Mon Jan 19 22:39:03 EST 2009
I've got a little question.
What keeps an auto-starting ROM Pak (Q signal tied to CART) from
continuously looping to $C000 instead of running the ROM code?
If BASIC is responsible for resetting the FIRQ behavior before
jumping into the ROM, I can understand how this would work right, but
if the CPU itself is responsible by using the upper hardware vectors
to jump directly to $C000 before BASIC even gets a chance to start,
then if the ROM code doesn't start with ORCC #80 (mask IRQ/FIRQ),
then I can't see the code ever getting past the first instruction,
which in some cases is a NOP.
Any ideas?
--
Roger Taylor
http://www.wordofthedayonline.com
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