Re: Apple II's paddle 3 button

[dalloff@gcfn.org (Dave Althoff Jr)]

Michael J. Mahon (mjmahon@aol.com) wrote:

: On a different but similar topic, which state of an annunciator
: output is "on" is a bit confused, as well.  The original monitor
: left the annunciator outputs in their default state on reset, but
: the autostart monitor authors apparently thought of them as
: active low outputs, and proceed to "set" the first two (AN0, AN1)
: to a low state and "reset" the second two (AN2, AN3) to a 
: high state.

: The monitor source I/O address mappings of the "set" and
: reset" addresses are even and odd, respectively, although
: most programmers think of "1", odd, high as "set" and
: "0", even, low as "reset".  Except for the INITAN code in the
: autostart monitor, the conventional usage is "active high",
: an interpretation which is also taken in later Apple II
: documentation.

...Which is also an issue if you are trying to make double hi-res graphics
work.  The original 80 Column Card Manual Supplement indicated that you
have to turn Annunciator 3 on in order to activate double hi-res; in fact,
you have to turn annunciator 3 OFF to make it work, as AN3 is already on
when the system comes up.

On a related note...does anyone have any suggestions for the best way to
de-bounce the paddle button input?  I've got an IR phototransistor
triggering my PB0 input on an old ][e, sensing when the spokes go by on a
K'Nex Ferris wheel, but I'm having trouble getting any accuracy out of it
because the signal bounces.  And yet, I need fast response...

--Dave Althoff, ][.
-- 
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