[Coco] DAC sound output and keyboard input

[Steve]

On 6/20/2014 3:04 PM, Mark McDougall wrote:
> I'm loathe to open that can of worms. The Apple joysticks have 2 
> buttons, for digging left and right. A single button changes the 
> gameplay significantly, for the worse IMHO.

The CoCo3 has two buttons on the joystick.  So what this talk of a 
single button changes the game play significantly?  Just use a two 
button joystick.

As for reading the joystick, you only need to see is the joystick below 
the 1/3 point and above the 2/3 point.  Anything in the middle range is 
no movement.  Just make sure you turn off the DAC to the sound output 
while doing the joystick read and write back the old DAC value when done.

On more item, add an NOP or two to let the DAC and comparer time to give 
you a true reading.  Reading the hi/low flag of the compare too quickly 
will give you "bad" readings.

To make sure they use a two button joystick, just use the second button 
to start the game.  No second button than no joystick for control.

That's how us old timers did it back in the day.

Steve