What are the 7800 cart and expansion port audio specs?
Cartridge Port Audio The EAUDIO signal on the cartridge port pin 18 is the same audio signal that you hear from your monitor or TV. It is provided to the cartridge port with the idea that cartridges could include the ability to generate their own sound in addition to the sound generated by the 7800 itself. For example, a cartridge could have a POKEY chip on board and it would put its output out on this pin. Expansion Port Audio There is no audio signal output on the expansion connector pin 17. Introducing an analog audio signal on this pin produces no results, whether this is because there needs to be a flag set in one of the I/O chips to enable external audio mixing (which I suspect is the case) or whether it is expecting a digital signal, I don’t know. In any case, you can’t pick up an audio signal from here for a separate audio output.
