[Coco] Re: CoCo Orchestra-90

[Andrew]

> The O-90CC's hardware is nothing more than two 8-bit
> Digital-Analog-Converters (DACs). You can take a multimeter, POKE some
> values between 0 and 255 to the memory locations
> 
> &HFF7A (left channel) 
> &HFF7B (right channel)
> 
> and measure how the voltage changes. If you connect the Pak to your
> amplifier and to the changes fast enough (e.g. a sine wave) or a
> digitized (sampled) voice, you would listen it (you should use assembler
> for doing so).
> 
> If you need multiple voices (e.g. 4-part harmony) you have to do
> something called time multiplexing or you have to add the samples and
> divide the result by the number of voices.
> 
> Hope that helps to get an idea.
> 
> Torsten
> 
> PS: it should be possible to use parts of the Paks ROM routines to
> output something from BASIC but I guess the ROM isn't documented.

Torsten - it helps a lot! Thanks. I was looking at the manual briefly 
(the scanned version I have on the Keil disk), and noticed that the 
schematic for it seemed rather simple - but I didn't enlarge it to check 
it out further.

I will have to play with those two memory locations (first, I need to 
dig my MPI out).

Andrew