This card provides stereo audio capability for the Apple IIGS computers.

This project was done in KiCad 6.0.6 and may not work with older versions.

Installation and use manual is a Google Docs file and can be found at this URL:

The J25 header on the IIGS motherboard provides an analog audio signal, and address lines to drive a demultiplexer which splits audio into Left & Right audio channels.

I'm using a 74HC4052D demultiplexer and a TL074CDR quad audio op-amp. There are other pin-compatible chips that can be substituted.