Introduction - What is BSOS?

BSOS (Bally/Stern Operating System) is a library of functions enabling an Arduino or other microcontroller to control a pinball machine. An adapter board interfaces the Arduino to the pinball machine's MPU (Main Processor Unit) either through a diagnostic port or the CPU socket. Then, the Arduino is able to control the machine's lamps, sounds, switches, and solenoids.

With BSOS, people have created new rules for many early solid state pinball machines.

The name BSOS originated because the library was written to work with the Bally AS-2518-17 and Stern MPU-100 architectures. Since that inception, the libraries have been expanded to accommodate other architectures, such as Bally's AS-2518-35, Stern's MPU-200, and Williams System 4-7 MPUs. Work is underway to support Atari, Game Plan, and Williams System 11 MPUs as well.