[Coco] Cassette Program Loading Help Needed

[Darren A]

On Sat, Mar 18, 2017 at 9:56 PM, RETRO Innovations wrote:

> On 3/18/2017 10:36 PM, Dave Philipsen wrote:
>
>> You could go about it in a completely different manner and not generate
>> the audio using PWM.  Just generate a straight square wave and feed that to
>> the CoCo.
>>
> As noted above, I thought of that, but early results were not encouraging.
>
> I thought for sure the resistor DAC would work, and I could get back to
> laying out the board, but I am back to diagnosing again.
>
>

Have you looked at how the MC-10 generates its cassette output?  It uses a
single output port pin on the 6803 MCU with a simple attenuator.

http://www.alice-dsl.net/d.j.peters/mc-10/circuit.png


- Darren