Yamaha CS80

> They use the same 
> ring memory table in the GX-1 and key assigner of the CS 50/60/80.  
> There is a somewhat cryptic explanation in the CS service 
> guide, pages 
> 11 to 19, describing the encoder for 4 voices.  JH references the 
> service guide on his CS50 page,

You'll find the GX1 KAS schematic here:
http://www.sequentix.com/gx1/GX1-KAS.zip

Are the separate assigner and octave chips used elsewhere ?
Looks like they were combined into a single chip for the CS synths, with a
matrix of keys rather than an input for every single key.

>   If you look closely you'll see the actual electrical 
> operation of the 
> key scanner is ternary, not binary, it uses both -6.5v to 0 and 0 to 
> +8.5v to derive logic states.

I'm sure that's not the case on the GX.
It has a +6/-9v supply for the assigner and octave scanning chips, but that
is just to limit the total supply voltage to 15v for the CMOS devices that
are used for the de-mux etc.

Cheers,
Colin f