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Jeff_Birt
PostPosted: Thu Jan 24, 2019 3:39 pm 
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Joined: Wed Jul 18, 2018 12:12 pm
Posts: 96
BigDumbDinosaur wrote:
Also, the SEI that the Commodore kernel inserts into the beginning of the NMI handler is unnecessary. IRQs are automatically disabled as part of the response to any interrupt.


Interesting! After looking at the kernel code this morning I was thinking about copying the kernel to the RAM under it and then writing my ISR address directly to $FFFA, to save the 5 cycle cost of the indirect jmp. Knowing that I can get rid of the SEI as well saves another two cycles.
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