Using an Arduino Nano plugged into J5 of the Bally AS-2518-17 MPU, I've rewritten the rules for Bally Black Jack to include the following:
* A Rolling Skill Shot
* Multiple levels of Top Lane awards
* Bonus up to 69k
* Ball Save
* Free Play mode
* Tournament Mode settable through front door switch
* Real Black Jack play (cards show on player displays, Hit with Player's stand-ups and Stand with saucer)
* Random Deck or Pre-programmed deck (to ensure fair tournament play)
The code an documentation is available here:
https://github.com/MrEkted/BallySternOS
(the PDF in the BlackJack2020 folder has all the build instructions and game instructions)
Here's a video of the game in action:
The daughter-card is built to allow dual boot (the machine can be booted to the old code or new with a switch behind the coin door). Here's a video of the dual boot:
The daughter card is easy to build (for less than $20 each). Here's a quick parts list that can build 3 boards:
Nano knockoff: https://www.amazon.com/Arduino-Board-ATmega328P-Without-Compatible/dp/B07XVYBR9Y/
Prototype board: https://www.amazon.com/Prototype-Snappable-Arduino-Electronics-Gold-Plated/dp/B081QYPHHP/
Connectors: https://www.amazon.com/Honbay-Single-Female-Connector-Arduino/dp/B06Y4S6G29/
With the addition of this switch, the machine can be booted to old or new code:
https://www.amazon.com/mxuteuk-Terminal-Position-Miniature-Dashboard/dp/B07XMH174C/
This is the same daughter card you may have already seen in my Stars2020 update.