Commodore 64 for grabs

Jim Battle frustum at
Mon Mar 27 23:25:41 CST 2006

David Griffith wrote:
> On Mon, 27 Mar 2006, Jim Leonard wrote:
>> David Griffith wrote:
>>> Here's a guy who's doing a very good job at replicating the SID on FPGA.
>> I am a complete noob on this subject matter (something that is most
>> likely going to get me booed off the stage in about five seconds) but
>> wouldn't there be a way to just, I don't know, slice open the chip
>> somehow and trace things to reproduce the chip exactly?  (Ignore
>> patent/copyright issues for now, I'm just curious in the technical
>> feasibility of the process.)  Is something like that possible?
> Theoretically, the SID handbook published by Commodore should be enough to
> recreate the SID.  Since NMOS isn't used very much anymore, that may be a
> roadblock to making exact copies.  There are some xrays of the SID on the
> web, which would be a big help.

I just did a google search and there is a patent on the chip -- it has 
already expired.  US Patent 4,677,890.

The chip is a hybrid digital/analog chip.  Duplicating it via pure 
digital means would be hard.  Apparently too the chip had bugs and so 
are unspecified, but people exploited those bugs for generating sound 

More information about the cctalk mailing list