Techno Stuff
How They Work - OK games before Bounty

There is one stepper unit that keeps track of the OK game level. It's called the red letter feature unit.

golden gate
red letter feature unit (click for big version)

The unit is an 8 step unit. One step for each score/odds level in the game. Recall the previous comment about all the game names having six letters. Even our modern math education can't quite come to grips with 6 == 8.

What actually happens is the first three steps of the unit all stay at the first OK level (G on golden gate). The main reason for that is that the first three steps of the odds are pretty much guaranteed to happen, so Bally wasn't going to give away the farm without it costing you. After that, the red letter moves at the same rate as the green odds on a screen game (or the red odds on a mystic line game, and we'll stop mentioning that right about now).

The red letter feature unit does the obvious thing of lighting red lamps behind the backglass via wiper A. Most of the rest of the unit is dedicated to controlling the stop relays which we'll get to in the part about game reset.

red letter feature unit advance

golden gate
red letter feature unit advance

The comment about the red letter feauture unit corresponding to the odds level is literal, and this is why. The unit itself is stepped up by a switch that is closed when the green odds step-up coil plunger is sucked in. Therefore, the unit stays in sync with the green odds unit.