Re: A86: Maskable Interrupts
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Re: A86: Maskable Interrupts
>
>isn't this the off routine?
>¦0c4c d303 out (#03),a ;turn off screen
out 3 should turn off the LCD but also enable both the interrupts (bit 1)
and the on interrupt (bit 0?)
that's really weird that the interrupts don't run .. it looks as though they
should
what is that exchanging for?
>¦0c4e fdcb129e res 3,(iy+#12) ;shift2nd
>¦0c52 fdcb099e res 3,(iy+#09) ;onRunning
>¦0c56 08 ex af,af'
>¦0c57 d9 exx
>¦0c58 fb ei
>¦0c59 76 halt
>¦0c5a 18fd jr #0c59 ; (-3)
>
>what is that if not a loop?
>if interrupts are shut off, they are shut off with external circuitry,
>not with di. there is no place in the rom where di is followed by a halt
yeah, I guess I was wrong. I looked at it many months ago .. that's a loop
:-)
>
>it seems to me that the calculator is always "off". in normal operation,
>(when it's not busy) it sits in a halt loop, waiting for an interrupt to
>tell it to blink the cursor or register a key. when you turn it off, it
>shuts down the screen and possibly disables the "200/sec" interrupt
>signal from whatever generates it. this is mostly speculation, but it
>makes sense.
from this I am guessing that the calc actually does run interrupts while
it's off
first because it's setting the bit to enable the interrupt and also using ei
second because a loop would be useless otherwise
third, where else would it break out of this seemingly infite loop from?
we could find out for sure if we knew what that exchange stuff was for