[Coco] CocoFlash Updates
go4retro at go4retro.com
Mon Sep 12 13:25:37 EDT 2016
With apologies to Zippster, but in July or so, Barry asked if I could
squeeze the Orchestra 90 functionality into the CocoFlash, so folks
could assume some additional sound options for games and such.
This Summer was hectic, but I was able to do so, and the conversation in
the list around the circuitry was very enlightening. The Orch90
functionality analog section is the top right of the cart, the R2R
ladders are most prominent. I used discrete resistors since I helped
with layout and I could get the wattage rating I wanted more easily and
In any event, the (hopefully) finished cart design is shown above. (The
wire is due to a trace issue caused by some debugging efforts). I have
verified the sound waveform matches the OR90 output, but has a but more
Vp-p, since I opted for some newer ABT-family latches, which drive to
the rails a bit better.
When I get some time, I'll put some more information on the design on
the web page, but feel free to ask questions if desired.
RETRO Innovations, Contemporary Gear for Classic Systems
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