The K42 has builtin hardware context saving for both the high priority and low priority interrupts, which would make most of what DT-INTS does unnecessary. The list of registers it saves is pretty complete.
I haven't looked at all the details, but it looks like you might get away with just calling the SavePBP/RestorePBP routines in ReEnterPBP-18.bas/ReEnterPBP-18LP.bas





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