Similarly, an NMI can hijack an IRQ, and an IRQ can hijack a BRK (though it won't be as visible since they use the same interrupt vector).
This is not usually a problem for an IRQ interrupted by an NMI because the IRQ will normally still be asserted when the NMI returns and generate a new interrupt. The BRK instruction, however, can effectively be cancelled by an NMI (or an IRQ) this way, so code utilizing BRK should be careful not to have a chance of coinciding with an NMI.
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