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Old 27 November 2018, 13:34   #15
grond
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Join Date: Jun 2015
Location: Germany
Posts: 1,920
Quote:
Originally Posted by roondar View Post
As far as I know the double access is only needed to slow down the CPU on certain A4000 configurations because it otherwise outruns the motherboard. Perhaps this can also happen on other Amiga's, but that's what I've always understood.
I think it also happened on the Vampire and probably also on 060s. If it is really just the CPU being too fast for the IRQ source to reset in time, then the problem should not occur if you acknowledge the IRQ at the beginning of the handler, then handle the IRQ and finally do the RTE, provided the handling takes longer than a second hardware write. If, on the other hand, the problem is related to the acknowledging signals settling and becoming stable before doing the RTE, only doing the write twice in a row would overcome the problem.
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