On Wed, 8 Jul 1998, Ethan Dicks wrote: > Check the B bit in the status byte on the stack to see if the IRQ was > triggered by a BRK instruction or a real hardware interrupt. Check the B bit also in the NMI handler, if the system uses lots of NMIs. There is a bug/feature in the NMOS 6502: an NMI can interrupt a BRK instruction if the NMI occurs before the 4th (or so) cycle of the BRK's execution (I've documented it in the 64doc file), and the B flag will be set in the P register value pushed onto the stack. Marko - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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