You can build a selector switch and push button test rig and only access the sounds that are located in the back layer of the sound selection. Without the first nibble you cannot access the entire board. The actual S & T fixture was a bitch to operate as it had a keypad that with time became intermittent. While you thought you entered the correct sequence you soon found out you had missed part of it due to bad pads.Front.JPG

I have not used it in years. If I remember correctly you had to enter the entire data string on the keypad and the control board separated them on delivery with the proper timing. What you entered appeared in the red display so you could verify your entry.