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Meterman58761
PostPosted: Mon Nov 08, 2021 5:37 pm 
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If the only interrupt I'm working with is driven by the NMI pin on the CPU, are any SEI / CLI instructions therefore meaningless?

Or are there internal IRQs within the processor that are not otherwise addressed by the user's code?
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BigEd
PostPosted: Mon Nov 08, 2021 5:44 pm 
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Indeed, SEI/CLI only makes a difference for IRQs, so no need for those, and if you have them they won't have any effect.
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Meterman58761
PostPosted: Mon Nov 08, 2021 7:57 pm 
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Thank you! It just amazes me the code I've been looking at even works with all the cruft and inefficient coding I've dug out so far.
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BigDumbDinosaur
PostPosted: Tue Nov 09, 2021 12:49 am 
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I suggest you read Garth's interrupt primer so you will become real familiar with how the 6502 reacts to interrupts.

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AndrewP
PostPosted: Wed Nov 10, 2021 11:50 am 
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BigDumbDinosaur wrote:
I suggest you read Garth's interrupt primer so you will become real familiar with how the 6502 reacts to interrupts.
Yup, I can second that; I've got it printed out behind me. I found it incredibly useful. That and your Investigating 65816 interrupts too (if using 65816).
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BigDumbDinosaur
PostPosted: Wed Nov 10, 2021 4:15 pm 
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AndrewP wrote:
Yup, I can second that; I've got it printed out behind me. I found it incredibly useful. That and your Investigating 65816 interrupts too (if using 65816).

The 65C816 interrupts article does repeat a few items in Garth's piece, but was focused on the 65C816's more powerful interrupt capabilities.

Incidentally, the 816 article posted here is out-of-date. The most up-to-date version is on my POC website.

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