[Coco] Coco game engine demo

[Robert Gault]

Richard Goedeken wrote:
> Robert,
>
> Is VCC still under development?  I could contact the author about fixing the
> incompatibility.  Thanks for letting me know about the audio buzz.  I know about
> this issue and was trying to avoid it when I wrote the joystick code, but I must
> have done something wrong.
>
> Richard

Richard,

There is some interest in having VCC "open source" but the author does not seem 
to be available for email.

Regards the Coco3 and the buzz, I believe I see where you turn the sound on and 
off in the joystick code. In general that ought to work but I'm not sure what 
will happen when the DAC has value A with sound ON, sound is turned off where 
the DAC gets a new value B, and then the sound is turned back ON. I'd expect a 
buzz. You may have to maintain the DAC at some fixed value by saving it and 
restoring it around the joystick routine. Could be a real pain if you envision 
your program supporting both music and joystick reading.
Also I noticed that you turn off interrupts after changing regDP in the joystick 
routine. That may be OK in your program but if there are pending interrupts, it 
would be safer to turn off interrupts before making system wide changes like 
changing regDP.

Robert