Commodore 64 for grabs

Jim Battle frustum at pacbell.net
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 
effects.




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