Sure the C64 can just be emulated, and there are kit allowing you to fit a RaspberryPi in a C64 case, and use the keyboard, but it's not really the same.
Even Commodore themselves weren't able to reproduce all of its subtleties (i.e., the 6581 vs 8580 differences).
Bob Yannes did some amazing things with the chip, especially considering the limitations he had to work under: http://sid.kubarth.com/articles/interview_bob_yannes.html
Analog circuits also tend to have high variation between units. You might have a perfect simulation of the average hardware, but it won't necessarily sound like your specific hardware. You'll need to measure your hardware and tune the simulation to match. People have done this for SID chips:
Of course digital has its place ... but nature chose to go with analog.
Theoretically you could reproduce this with discrete components if you can figure out the entire circuit. That would be a pretty epic build that I'd love to see!
Any venture will require sufficient funding - and (by necessity) produce sufficient volume that it creates a pile of press - that nobody will touch it unless the copyright and IP issues are 100.00% cleared by a very large pile of lawyers.
The term of protection for IC layouts is only 10 years in the US --- i.e. long expired.
$2000 per sq mm for fabrication
That's if you want to use the newer processes; if you're reproducing old chips, something like 0.7um CMOS (already considered "old" today, those in the C64 are multiple-um) is only ~$300/mm^2:
And thanks for the notes about CMOS, I'm very interested in chip design and $300 is rather affordable for hobbyist-level tinkering. Now just to have chip design tools take off... :)
Wow, this is kind of sad.
I'm cynical any laws implemented now would truly protect though, considering the state the world seems to be in...
His content is fantastic.
Damn. Now I wish I'd bought that pile of used C64s stacked in the thrift shop window that day.
its analogue components, such as the filter, which are very hard to simulate digitally.
Analog's day came, went, and will be back again ... because for sound it's just superior in -many- ways. And hacking is hardware, not software.