Yamaha CS80

I built a CS-KAS based on PICs a while ago. It works, but I did not 
adopt their strange assign order and instead went with the two popular 
ones, "steal oldest note" and "steal least used note". I need to finish 
that thing, it still needs the gliss/porta function to actually work. 
Never enough time...

Scott
Doesn't the CS have, already embedded, a "steal the oldest" logic which integrates with this weird pitch code encoding+LRU?
Basically, for what I could understand, in a Sustain-II state, if you have all 8 voices playing and have a new note playing, the oldest voice playing is stealed by the new note

Yes, this is a common Yamaha trick, though nothing beats the -12V 
logic of the GS1, with a -7V supply node for the 5-volt logic (the patch 
controller). Gotta love that old PMOS technology... ;)

I seemed to understand that the GS-1 assigner operates with a very similar logic, compared to the original KAS, have you got any more resources to share with us perhaps?

Cheerz
M



  ----- Original Message ----- 
  From: The Old Crow 
  To: yamahacs80@yahoogroups.com 
  Sent: Thursday, February 19, 2009 5:53 AM
  Subject: Re: [yamahacs80] Voice allocation ?


  Colin f wrote:
  > 
  > 
  >> 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.
  > 
  They integrated the octave and semitone into a sort of matrix; it 
  would first sense the octaves of keys by setting the octave pins to 0V 
  (a grey bit, not logic 1 or 0) and setting the note pins to logic "1" 
  aka -6.5v. IT would record the octaves found in a buffer. Then it 
  would *reverse* the sense of a key and set all the 1s (-6.5v) to 0s 
  (+8.5v). This would show which actual notes in each octave were 
  active. Then they pack up the 3-bit octave code and 4-bit note code for 
  good old time-division multiplexing at the DAC. Skew the clock, and you 
  get the glissando/portamento. What a weird encoder. :)

  I built a CS-KAS based on PICs a while ago. It works, but I did not 
  adopt their strange assign order and instead went with the two popular 
  ones, "steal oldest note" and "steal least used note". I need to finish 
  that thing, it still needs the gliss/porta function to actually work. 
  Never enough time...
  >> 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.
  >
  > 
  Yes, this is a common Yamaha trick, though nothing beats the -12V 
  logic of the GS1, with a -7V supply node for the 5-volt logic (the patch 
  controller). Gotta love that old PMOS technology... ;)

  Crow
  /**/


  

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