[Coco] Microbes - audio distortion from joystick movement?

[Richard Goedeken]

There are some unfortunate limitations of the analog interface circuits on the
coco.  If you are playing music in a game (through the standard 6-bit DAC
output), it is impossible to read a joystick axis value without disturbing the
audio signal.  There are things you can do to minimize the disturbance but not
eliminate it.  Arkanoid also has a buzzing sound in the audio output, due to
this effect.

Richard

On 03/07/2015 07:31 PM, Jeremy Michea wrote:
> Was playing my microbes cart tonight and noticed that there would be some
> audio interference like a buzzing sound that would increase or decrease in
> intensity depending on the movement of the joystick as the ship zipped around
> the screen. Seemed to happen no matter if I used a Coco 1,2 or 3 and in the
> case of a coco 3 it would happen with both RF and composite. Could only test
> this one cart as it's all I have but I haven't tried it via drivewire to see
> if it happens with a virtual cart as well. Cleaned the cart contacts, which
> had no effect.
> 
> Any explanations as to what might be causing this?
>