[sdiy] polyphonic synthesis

[mikko.a.helin at nokia.com]

> As i am in the process of building my own polsynth which uses SID
> chips for its voices, i am thinking about keeping them in tune.
> These chips derive their clock from an 1 MHz crystal oscillator.
> Would it be better to use an extra oscillator for every voice card,
> or shall i use one master oscillator and distribute this clock ?
> (i hate the idea of having an 1 MHz square signal all over the synth,
> even if the frequency itself nor the harmonics will be far 
> above audio range)

1 MHz isn't that high frequency though it would still be better to have use
the master oscillator.

> 
> Any thoughts ?

What microcontroller are you going to use? That would be nice AVR or PIC
project, right? You need just the data lines and five address lines, control
line (R/W), chip select (CS), clock and /reset signals (clock derived from
the mc clock down to 1 MHz). Are there any special issues for timing? 

www.hardsid.com site has some nice mp3's made using their PC ISA card for
SID(s). Interfacing SID to PC parallel port looks easy, but unfortunately I
can't use parallel port for much else than Cubase dongle.

-Mikko