EM Pinball Scoring without Chips with Mark Gibson

TL;DR

Mark Gibson explains EM pinball scoring circuits without chips using electromagnets, relays, and mechanical logic.

Summary

Key Claims

• Electromechanical devices require motion to perform computation; they use motion to open and close switches to evaluate circuits, unlike solid-state games where motion is primarily for ball movement and toy activation.

  high confidence · Opening section contrasting EM and solid-state device design philosophies

• A single pulse from a target switch can be converted to multiple pulses using a score motor with cam switches that fire multiple times per 180-degree rotation.

  high confidence · Explanation of how score motor cams fire at different frequencies to enable 50-point scoring from a single target switch pulse

• Score reels advance only when the coil power is cut and the spring pulls the plunger back; holding the switch closed does not advance the reel.

  high confidence · Score reel mechanism explanation and live demonstration showing that digit rotation occurs on switch release, not closure

• Lock-in circuits use two parallel paths: one to trigger a relay from an activation switch, and a second to keep the relay active indefinitely until a release switch opens.

  high confidence · Detailed lock-in circuit explanation using activate and release switches

• Score reels have at least one, usually two switches that open when the reel reaches zero position, which are used to stop the reset motor at the correct position.

  high confidence · Reset circuit explanation with detailed animation showing how zero-position switches control reset sequence

• The characteristic 'dot' sound heard during EM game reset is the five pulses from the score motor's cam that fires five times per 180-degree rotation.

  high confidence · Discussion of score motor pulse timing: 'It's endemic to all the EM games. They all do it.'

• Carry logic in scoring allows advancement of a higher-denomination reel (e.g., 10-point) when a lower-denomination reel (1-point) reaches position nine and advances to zero.

  high confidence · Carry circuit explanation showing how 9-position switch enables 10-point relay when 1-point reel advances from 9

Notable Quotes

• “Electromechanical devices or games require motion, right? We talk a lot about solid-state games, you have motion, but that's primarily to kick the ball around and to activate the toys and things. They don't require motion to do computation. Electromechanical devices rely on motion to actually do the computation to open and close switches to make things, to evaluate circuits in the game.”

  Mark Gibson@ 0:49 — Core thesis distinguishing EM game architecture from solid-state design

• “It's not until the power goes away that the digit actually rotates to the next position.”

  Mark Gibson@ 15:46 — Key insight about score reel operation that distinguishes EM scoring from intuitive expectations

• “If you ever listened to an EM game reset right it's dot. Those are the five pulses that come in chains like that right. It's endemic to all the EM games. They all do it.”

  Mark Gibson@ 25:41 — Explains the distinctive audio signature of EM game reset as technical consequence of cam design

• “This is a lock-in circuit that's going to remember I owe you 50 points, and I can't let go until I've given you those 50 points.”

  Mark Gibson@ 26:36 — Illustrates how lock-in circuits implement state memory in mechanical circuits

• “So there has to be another piece of intelligence in there, another switch somewhere that says how far to roll forward.”

  Mark Gibson@ 30:01 — Explains the necessity of zero-position switches in implementing bounded reset behavior

• “It's like if you've ever seen a player piano roll, right? The holes tell the notes when to fire. That's kind of what this is showing you.”

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