[A83] Re: 83p os
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[A83] Re: 83p os
> If you already change the jumps you can also check that no program has an
> IM2 instruction in it. But when you have self modifying code it's very
> difficult to check.
It's even worse. IM 2 translates to ED5F, but a program can very well
contain
ED5F without switching to interrupt mode 2. For instance, 21ED5F is
perfectly
legal, as it means ld HL,$5FED. But checking the byte before ED5F does not
guarantee anything either. Consider the following:
DirtyTrick:
ld HL,$5FED
... some code ...
jp DirtyTrick+1
The only "solution" that I can think of is telling programmers they're not
allowed
to use IM 2, and trust they'll comply.
Rob van Wijk
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