Re: A86: LCD stuff
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Re: A86: LCD stuff
Now that can't be, because I use this code to turn off the calc. I
don't have any DI instructions in there. If the halt finished because
of a normal interrupt, then it would go to the code to turn the screen
on, but mine never turns it back on until ON is pressed.
Cassady Roop
David Phillips wrote:
>
> http://ti86.acz.org/routines/calcoff.asm
>
> That isn't entirely correct. To turn off the calc, you turn off the LCD
> _and_ disable the timer interrupts. Then you go into HALT mode, which waits
> for interrupts. Normally, this would break somewhere in the next 1/175 of a
> second (according to my experiments that's closer than 1/200). But of
> course, you disabled them. So the only interrupt left to occur is the ON
> interrupt (which I think is an NMI, but can't say for sure...but if not,
> shouldn't DI \ HALT lock the calc?). Which is why it sits at the HALT until
> the ON key is pressed, which then executes the code to turn the calc back
> on.
>
> If you're further interested, I suggest reading the interrupt sections on 86
> Central. It's more or less accurate, and has dissassembled, commented
> portions of the boot and interrupt code, so you can really see and
> understand how it works. Also explains how to fix the down-left bug...
>
> > check out this
> >
> > CalcOff:
> > ld a,1
> > out (3),a
> > halt
> > ld a,11
> > out (3),a
> > res onInterrupt,(iy+onflags)
> > ret
> >
> >
> > i got it somewhere from acz
> > the first 2 lines turn off the screen (i believe)
> > then it waits for ON to be pressed
> > then resets the on key press so the system doesn't act
> > on it
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