Re: A92: 256K & interrupt routines
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Re: A92: 256K & interrupt routines
Even if you use the higest wrap-around, someone might eventually find a
way to have 1MB of internal ROM. You should say in the FAQ that this is
a possibility, and that programmers should realize this. Other than
that, use the technique.
Chris Lambert
clambert@geneva.edu
calan@hotmail.com
URL: www.geocities.com/siliconvalley/peaks/6869
On Fri, 24 Oct 1997, Bryan Christopher Turner wrote:
> On Oct 23, 3:49pm, Jean-Jacques MICHEL wrote:
> > Subject: RE: A92: 256K & interrupt routines
> > >>> Could somebody justify the use of :
> > >>>
> > >>> move.w #$2700,sr
> > >>> move.l ($020064),old_int_1
> > >>> move.l #int_1,($020064)
> > >>> move.w #$2000,sr
> >
> > >>It saved you the trouble of setting/clearing the bit that
> > >>enables/disabled the "unauthorized writing under $120" trap.
> > >>It's the same technique used by Fargo itself - the memory wraps around
> > >>at $020000, and the trap isn't activated "up there".
> >
> > That's pretty obvious, why didn't I thought about it sooner ?
> > Thank you for your answer.
> >
> > May I suggest then to use $040064 instead...
> > (I tested SPRITE.ASM with this and it worked fine with my 256K Fargo v1.7
> :-)
>
> This was discussed way back when, and yet I think only two programs have
> supported this feature. I would like to get this little tidbit added to the
> programming FAQs. In fact, we should use the highest possible address instead
> of the 'next' wrap around. I believe this would be $0E0064.
>
> --Bryan
> bcturner@eos.ncsu.edu
>
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