LZ: The final word on APD in asm shells...
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LZ: The final word on APD in asm shells...
Well, over the last couple of days, I have perfected the APD information
I recently discovered. :)
THE FINAL WORDS ON APD (I hope):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The APD feature in the TI-85 is handled by an interrupt, and uses two
bits. These are bits 2 and 3 of (IY+$08).
Bit 2 of (IY+$08) is the "Master Enable"; it COMPLETELY ENABLES the APD
feature if set, and COMPLETELY DISABLES the APD feature if cleared.
Bit 3 of (IY+$08) is cleared if set when APD occurs (otherwise it
appears to remain clear).
RAM Address $8008 is used as a timer; it is apparently decrimented every
time an interrupt occurs if both of the above mentioned bits are set.
RAM Address $8009 is used as a secondary timer, which is decrimented
every time $8008 reaches zero.
The routine at $0115 can be used to reset $8009 to $A1. PLEASE NOTE
THAT $8009 IS _NOT_ RESET WHEN A KEY OTHER THAN [ON] IS PRESSED, you
will have to reset it by doing "call $0115".
~~~~~~~~
Now will someone please add this to TI-RAM.TXT??? ;) *thinks* Gee, I
ACTUALLY made a contribution (though minor) to that file... :)
I hope that someone finds this helpful... ;)
Cheers,
--
~Keith
TSK3000@Prodigy.Net
----
SAVE BATTERIES!
USE APD IN ZSHELL NOW!!!
set 2,(IY+$08)
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