Yamaha CS80

Greetings CS experts,

Just joined this group since I'm working on a little project and 
thought someone might know the answer to a question that's been 
bugging me.
As I understand it, the voice allocation on the CS80 only cycles 
round 7 of the 8 voices, unless more than one note is played, in 
which case the eighth voice joins in.
Is this correct ?
This is how the assignment works on the GX1, which is my real area 
of interest, but I figured there were more people around with CS80s 
who might have figured this out (if it is also true on the 80).
The only explanation I can think of as far as the GX goes is that 
the presence of a 7/8 voice switch to limit the KAS to using 7 
voices instead of 8 meant it was too complex to implement the voice 
allocation IC otherwise. Presumably the 7/8 voice switch is there to 
work round a dead M-board.
Does the CS80 also have a 7/8 switch ?

Cheers,
Colin f