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Forcing an NMI or locking the keyboard via poke command
Posted: Sat Mar 30, 2024 7:34 pm
by Crayon21
Anyone know how to do this? I want to force a halt then an NMI if the user tries to breakout using f2 or space or rubout. it's for the eightyone emulator using the zx81. however I don't want it to be found in the listing. any ideas?
Re: Forcing an NMI or locking the keyboard via poke command
Posted: Sun Mar 31, 2024 11:52 am
by 1024MAK
You can't force a NMI. A NMI is a non-maskable interrupt which is a hardware signal. Machine code can jump to the address where the NMI routine is, but it's not quite the same.
Machine code can HALT the processor, just execute the HALT instruction. But this will not do what you want on a ZX81.
I presume you actually want to prevent a user from BREAKing into the program?
Someone came up with a solution, it's in this
topic
Mark