[net.micro] External input to C 64 SID chip

PHORWITZ@BBNG.ARPA (04/26/84)

Does anyone out there know how one connects an external source
(e.g. a microphone) to the SID chip, to run it through the
filter and add it to the synthesized sounds?  The Programmer's
Reference Guide talks about connecting to "pin 26", or some such,
but I couldn't find any explanation of a straightforward way
to do this.

Paul