[Coco] How Many OR90s can be utilized?

RETRO Innovations go4retro at go4retro.com
Sat Nov 12 01:20:19 EST 2016


On 11/12/2016 12:14 AM, Bill Pierce via Coco wrote:
> Jim, with all the "voice mixing" that goes on to combine 4 and 5 voices in a normal Coco music program, I don't see why you couldn't output straight to several ports instead of mixing.
> If the music program does like orch90 and preconfigures the frequencies for the whole song (the "SCORE" function), the output would be a mater of reading x number of bytes, each being sent to a port.
I understand, it's balancing the capability, which few might use, and 
the silicon area it takes to implement.
> I think 6 or 8 could possibly done. But of course this would be a music only program... no "background" sound for games or anything. And as you know, the ports would need separate addresses, preferrably inline.
Well, or a preamble to slide one set into focus.
> In the CocoFPGA, Gary implemented 16-bit dacs. They will run as stereo 8-bit normally, but writing to two extra addresses (along with the first 2) causes it to go into stereo 16 bit mode.
Any idea what the addresses are?
> I've yet to experiment as there's no 16-bit software for the Coco, so I need to find some good samples to play with. Of course ther CocoFPGA can run at 25mhz with 4 meg of memory available, so that helps :-)
Yes, there would seem to be no reason to spend much time on this if the 
ability to output samples is limited to 2 channels.

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> Bill Pierce
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