Hi do anyone Know which PIN i have to connect for record from extern source (Smartphone or MP3 player) to the datasette?
While saving from the commodore 64 you can read data on wire A, the low data 0.3 Volt, the high data is 3.4 Volt. When saving just by switching S1, you provide the same signal yourself. I recommend to apply 1.8 Volt bias voltage.