- Make sure the jumper is pointing to Terminal and you use a straight through serial cable. Do not use a printer cable or null modem.
- Make sure the SSC is in slot 1, 2, or 3
- Make sure the dip switches match the ADT pro instructions
- You can connect directly from the mac Terminal to test things out:
screen -L /dev/cu.usbserial 300,cs7,cstopb
(replace cu.usbserial with the actual name of your device in the dev folder)
Then, after reset, if you do PR#1 and IN#1 on the apple II, you should be able to send text back and forth.