Re: A92: 256K & interrupt routines
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Re: A92: 256K & interrupt routines
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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