[sdiy] Place to start with 3E dev kit

[Eric Brombaugh]

Rainer Buchty wrote:
>> So I'm thinking you could use the 3E to emulate a SID chip? (or 
>> several?)
>>     
>
> http://www.syntiac.com/fpga64.html
>   

That's a pretty cool project! Unfortunately, it looks like he's not 
fully emulating the SID. I grabbed the source and looked at the VHDL (Ow 
my head! :) ) and all that's in there are a few NCO-based sawtooth 
oscillators with volume control. The EGs and noise generator are not 
modeled, nor are the ring modulators.

 From what I understand, the SID has a fair amount of analog circuitry 
in it. To emulate that on a typical FPGA you're going to need to come up 
with accurate DSP models for the multi-mode filter, which while not 
impossible may be quite time consuming. Without the filter it's really 
not a SID.

Eric