Re: A86: Questions on Port 3, calc on, off, APD, etc
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Re: A86: Questions on Port 3, calc on, off, APD, etc
>> 3.) When the calculator is off, does the interrupts run in the background
or
>> does it disable timer interrupts and wait for an ON interrupt. Does
anyone
>> have any details on this?
It does this both in the startup reset (before calc is on), and in the
shut_off routine
; $00 $01 -> Port 4
0e56 97 sub a ;out (3),0
0e57 d303 out ($03),a
0e59 3e01 ld a,$01 ;out (3),1
0e5b d303 out ($03),a
0e5d fb ei ;enable interrupts
0e5e 76 halt ;wait for interrupt -
As you see, it has no DI. The $00 $01 appears to disable everything but the
ON key interrupt. It is perfectly possible to override the default interrupt
handler with IM 2 and create your own shut down routines from which
interrupts would run in the background. Basically means only the LCD would
shut off. Would this consume too much more power? Maybe.
>It disables the maskable (timer) interrupts, turns off the LCD, and halts.
>The only way to get out of the halt is through a non-maskable interrupt
>(the ON interrupt).
>
>> 4.) The calculator appears to turn on immediately when you put batteries
in
>> it, executes a HALT and waits for the ON key before it initializes. Is
this
>> correct?
>
>I believe it is, though I am not sure on that.
>
>> 5.) Does the calculator do different things if it is shut off depending
on
>> whether it what caused by the APD shut it off or [2nd][ON]. It appears to
>> have a difference
>
>APD just turns off the screen, DI's and HALT's. When you turn back
>on the calc, it's state will be identical to the way you left it. [2nd]
[ON]
>exits to the homescreen and restores the stack as well. You exit what
>you were doing.
No no the calc_off doesnt use a DI, in fact it uses an EI. The calc doesn't
have any Non-Maskable Interrupts. You can, I believe, disable (mask?) either
the timer interrupts or the ON key interrupt. I shall do experiments to
figure out this.
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