[sdiy] Siel opera6 schematics

[Tom Wiltshire]

Sorry, my mistake. Neil's right. Opera 6 uses tone generator chips  
driven from a VCO, not 8253 counters.

A couple of comments about the hard-to-get chips;

> According to that site the following would be my 'difficult-to- 
> obtain' chip list:
>
> SSM2024        Quad VCA . . . . . . . . . . . . . . . NOS    16.50

The SSM2164 datasheet includes some details on replacing SSM2024 with  
the newer (and still in production) SSM2164. This might get you out  
of a corner if you thought it worth the effort.

> MM5837N        Noise Generator  . . . . . . . . . . . Out of stock

I've done a 8 pin PIC 16F copy of this which would work. Ask me if  
you're interested.

Regards,
Tom