Notes From Maine – 1

In my house there’s a bathroom off of the laundry room and another down the hall. The last time they came to visit, my sister and I were cooking dinner when I heard my nephew talking to himself as he walked through…

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Diagnosing a Gottlieb System 80

Recently, I got a "The Amazing Spider-Man" (Gottlieb 1980) that won't boot. I've never worked with this architecture before, so my diagnostics might seem a little haphazard, but this is my plan: Make sure the board has good power and the chips…

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Stars 2020 – New Rules

The original rules for Stars were pretty simple. A set of drop targets would advance the bonus, light extra ball, and then special. A spinner between the drops was worth 200 and it ramped up 400 more for each center drop. If,…

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Until Dawn

In the middle of the night, there are creatures who hunt. Once they catch your scent, they will track you down. Nothing will stop them. The only way to survive is to fight UNTIL DAWN. This story will grip you from the…

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Software – Bally/Stern OS

My goal for this software is to create an Arduino-based pinball operating system for Stern MPU-100 and Bally AS-2518-17 machines. Programming for Arduinos is very simple and the IDE isn't wonderful, but it's free. The OS will take care of all of…

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Switches

Reading switches is the easiest part of this process. The switches are organized into banks of 8, and each bank is energized by a different switch strobe. The lines U10A:PA0-PA4 are the strobes and the return values are read on U10B:PB0-PB7. A…

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Solenoids

The M6800 implementation of solenoids uses the 120Hz ISR to control the solenoids. They did this for several reasons: Time out the duration that solenoids are kept on. According to the Bally Theory of Operation document most solenoids need to be kept…

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Lamps

Compared to the displays, writing to the lamps is fairly easy. Well, that's not exactly true. It's fairly easy once you understand how they're using the MC14514 chip, which actually took me a little while to figure out. My first attempts weren't…

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Displays

The games I've worked on have five 6-digit displays. There are four player displays and one for credits/ball-in-play. These displays only show one digit at a time, but they flip so quickly between them that it looks like all six are on…

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PIA Chips – 6820

The 6820 PIA (Peripheral Interface Adapter) chips are how the M6800 talks to the outside world. They're used to either latch data to send to the lamps, display, or solenoids, or they're used to grab input data and hold it for the…

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