I recoded my Stern Stars (1978) by replacing the processor with an Arduino Nano, and created a generic Bally/Stern OS you can use to make new rules for your early SS Bally/Stern
AS-2518-54 BPS054 - Voltage rectifier board
PINBALL: Repair Bally 6803 Pinball Games 1985-1989.
6802 MPU
Nuova Bell Pinball Repair information Bell Cobra pinball
RD-MPU9211 Rottendog Williams System 11-11C MPU Board
PBL-600-0442-00 MC6808P 40-Pin MPU Chip
Bally -35 led stuck on - Pinball Technical and Repair Questions - Aussie Arcade
Repairing ALL the Boards in This Bally Lost World Pinball Machine! - YouTube
PINBALL: Repairing Bally, Stern Pinball Games 1977-1985, part two
PTK-WPC89 - WPC89 System MPU board
Pinball Repair | I hope you are ready for the Dumbest Question In Pinball Repair Ever
PINBALL: Repairing Bally, Stern Pinball Games 1977-1985, part one
AlltekSystems
BALLY MPU Kit Assembly Log
Nuova Bell Pinball Repair information Bell Cobra pinball
MA-09-011-052 - LED flicker eliminator kit Bally aux lamp board AS-2518-52