Now that things are mostly working I decided I wanted to see if I can figure out how to get a coin into the machine so I can play.
At this point the system comes up with a single screen that just says "CALL ATTENDANT". If I open the door and press the "Self Test" button. The screen to the right is shown. It appears there is some missing data in my external RAM.
The RAM is usually kept via a battery attached to the motherboard. If you replace the battery or pull the RAM chip, you will lose all the contents inside. This is where the coin counts and settings are stored. I have been playing with those values for a while, but now may be at a point where I need to see what a valid RAM looks like.
I will be dumping a "Set and Clear" ROM that is used in real life to fix such an issue. I will need to disassemble that source of that and figure out what it is doing in order to make my RAM match what a real machine would have.