More speculation: Found an Alarm Keyboard @ $ 1.49. Electronic Goldmine, G 17927; 12 keys, 16 wires, 6 LEDs. Might have a wire per key which if true, & using storage, would allow entering 4- 3 bit nos. or 3-4 bit nos. Dip SWs still used for internal combination. If interested in 3 numbers, I might buy one to check it out. If as expected, could send it on. Need a few parts anyway.