4066 Add-On Board
This board allows multiplexing of the analog signals on gameport 1 and 2.
Normally you don't need the 2nd 4066 in the C64, but for the very rare case where it is needed, this board can be used to upgrade the 2nd 4066 chip.
5V Pin -> 5V GND
Pin -> GND
Keyboard COL 6 / 14 Pin -> Keyboard header Pin 14
Keyboard COL 7 / 20 Pin -> Keyboard pin header Pin 20
Note: On some boards the AX/POTX/AY pins are already present and can be connected 1:1. On other boards the following pins have to be connected:
POTX Pin -> SID Pin 24 (POTX)
POTY Pin -> SID Pin 23 (POTY)
AX Pin -> Gamport 1 Pin 9 AY Pin -> Gamport 1 Pin 5
BX Pin -> Gamport 2 Pin 9 BY Pin -> Gamport 2 Pin 5