Installing an RPU (Rev 4 or 102) board onto an MPU (Bally/Stern/Williams).

It’s the cable.

Instructions on how to source parts and solder them together to make your own RPU board for cheap.

A list of all the reasons you might not be getting sounds, and the ways you can fix those issues.

The 6820 PIA (Peripheral Interface Adapter) chips are how the M6800 talks to the outside world.

The Stern MPU-100 is identical to the Bally AS-2518-17 board. At least I think it is. I’ve worked on both…

Storm 23 - all new code that can run on Stern Lightning (1981)

The new RPU OS library can handle many different MPU architectures.

Installing new code on your machine is relatively cheap & easy. There are plug-and-play and DIY approaches available. You can write your own software too if there’s no new code available for your machine.

Rewrite of Supersonic (Bally 1979) with all new rules, sounds, and modes.

This is a fast, widebody, 4-flipper shooter from Stern (1980). The theme features big game animals (tigers, lions, etc.) and has 9 …

This project began with a need to fix an old Stern Stars. Once it was playable, the real work began.

What’s the point of this site? Weren’t these games perfect as they were released 40 years ago? Maybe…

But maybe there are new ways to enjoy these classic pinball machines!

Trident is a great game. Trident with 4-ball multiball is insanity …

After repairing a Stars machine (Stern, 1978), I started thinking about how I could improve the rules of the game. Stars is fun, but …

The games I’ve worked on have five 6-digit displays. There are four player displays and one for credits/ball-in-play. These …

Interfacing the Arduino Nano to the MPU is really easy using the J5 connector on the board. The J5 connector is at the …