An original System 4 MPU board as found in the following pinball machines.
WILLIAMS PINBALL MACHINE SYSTEM 6 MPU / CPU BOARD
WILLIAMS PINBALL MACHINE SYSTEM 11c MPU / DRIVER BOARD
WILLIAMS PINBALL MACHINE SYSTEM 11 MPU / DRIVER BOARD
Williams Pinball Machine Sytstem 6 - 7 Speech Board
Faulty - Williams Pinball Machine WPC Power Driver Board - Spares Or Repairs
