开云体育

Hi Scott,

I tried emailing you directly from you site but they kept bouncing
back... glad to have bumped into you here. I have a question for you.
It's about the selection of which voice is playing (great site by the
way) when tuning. You say on your site that the voices play in order
after switching on. But to get voice 8 you have to hit a key 4 times
and hold it, and the next voice played is voice 8. This is slightly
confusing - are you saying that after powering on you can hit single
notes and it will increment from 1 to 7? But you need to do the "4
hit - hold and then one hit" for voice 8 ONLY????

I hope that I've explained my confusion un-confusingly...?

Cheers for now.
TOM


--- In yamahacs80@..., The Old Crow <oldcrow@o...> wrote:

Some of you probably know me (by name if not by reputation),

others

might be seeing me for the first time. My name is Scott Rider, aka

the

Old Crow

The original key encoder is a strange bit of logic. Originally designed
for the 4-voice CS-50, but with options to assign from 4 to 8 keys, some
of the logic for 4 voices still applies. The key rollover logic triggers
voice 8 if voice 4, 5, 6, or 7 is in use. So, the pressing a key 4 (or 5
or 6 or 7) times and holding it while pressing another key is the only way
to sound voice #8. At least it is the only voice number that needs this
keying method.

I think the key assigner chip is kit-bashed from one of Yamaha's organ
key encoders, which typically (in 1975) encoded up to 7 keys per manual.
Adding that 8th note involved a bit of 'bodge-work' to the existing 7-key
design.

The actual reading of keys is also interesting; they used a ternary
(base-3) encoding system, which is hard to do in a modern 5-volt-only
microcontroller. (I don't even try to do the ternary encoding in my
microcontroller code for the KAS replacement project. Much easier to do a
"normal" binary key-scanner and frob the results into Yamaha-like keycodes
and time slots.

Hope this helps,

Crow
/**/

Yes, thanks Scott.

It all makes sense now...;^)

Cheers.
TOM