Many thanks to Greg Edlund of IBM for organizing the DesignCon 2004 panel discussion, "Establishing Pass-Fail Criteria for High-Speed Digital Interfaces", and for inviting me to make this 5-minute presentation alongside other presentations from Edward Sayre, Robert Haller, and Dale Becker.

If you've ever been to Las Vegas you probably saw a "quarter pusher" arcade game. In this game the machine holds a flat tray chock full of quarters. The quarters are piled so high that some dangle precipitously over the edge of the tray, just beyond your reach inside a heavy glass casing.

As you drop your coins one at a time into the game, the machine wiggles and pushes your new coins into the pile from the back side, pushing the remaining pile of other coins forward, moving them closer and closer to the point where a clot of quarters might cascade over the front edge of the tray, out the chute, and into your waiting arms.

To maximize the visual effect, the game is designed so that it pushes a lot of coins very, very close to the edge without actually tipping that many over...

That game reminds me of the way we sometimes design high-speed digital circuitry...

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