[A83] Re: 83p os
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[A83] Re: 83p os
You could always release a modified assembler :)
corey
>> 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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