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Is how slots are programmed a well-kept secret?

29 December 2006

I have a couple of questions that have plagued me for quite a while.

1. Is there any knowledge out there about how slot machines are programmed, or is this a well-kept secret? (I see the same layout of reels on a repeating basis, some kind of a cycle appears to be present on the way the reels display "almost jackpots").

2. How do the casinos that report a "94%" payback on their slots actually do that, since the slot machines are supposed to be operating on a random number generator? Or is there another program running in them that keeps track of paybacks and modifies the RNG so that they meet the 9x% paybacks or makes sure that the house gets it appropriate cut?

3. Are there programs running in slot machines besides the RNG that observe the number of coins played and adjust the probabilities based on that. (For example: Are you just as likely to hit a significant jackpot if you only play 1 coin per line, or do you have better odds on getting a significant jackpot by playing 5 or 10 coins per line?)

4. Is there a network that the slot machines are connected to that allow them to report back to casino management how much they take in and how much they pay out at any given time that management wants to poll them?

5. Is there any truth that the $1 slots have a higher payback than the quarter or nickel ones? And if so, technically, how do they do that, since I have always heard that the outcome is totally random?

Thanks for any info that you can provide.

1. Yes, there is plenty of information available about how slot machines are programmed. There are many articles on this site about that subject. The problem is that many players do not believe that whatever patterns they think are present are not the result of the random selection of outcomes, but instead are the result of a grand conspiracy among slot manufacturers, gaming commissions, testing labs and casinos to manipulate the machines.

Virtual reels are laid out to show near misses by having the blanks above and below a jackpot symbol appear on the reel more times than the jackpot symbol. Another technique is to have more jackpot symbols on the first two reels than on the third reel.

The only reason you may see these combinations on a repeating basis is that they are likely to occur. An analogous situation is frequently drawing a red marble out of a bag of 70 red marbles and 30 blue. You get "almost jackpots" so frequently only because they are more likely to occur than a jackpot.

2. Any manipulation of the results determined by the RNG is illegal. The only thing random on a slot machine is the result that will land on the payline next.

Let's go back to my bag of marbles. We'll draw one without looking, note its color, and return it to the bag. We have no idea what color marble we'll draw next, but we do know that over a large number of draws, about 70% of them will be red and 30% blue.

On the slot, we don't know what combination will land on the payline next, but we (or, at least, the casino, manufacturer, and gaming commission) know that the combination is drawn from a pool of combinations that pays back 94% and so the machine will pay back 94% of the money played in it in the long term.

3. The number of coins you play has no effect whatsoever on the symbols that land on the payline. Coins played is taken into account only when determining how much you should be paid for a winning combination.

4. Yes, slots are networked so they can report how much they've been played and how much they've paid out to a central accounting system. The network is also used to track play for the slot club and to report events on the machine (such as hand-pay required, for example) to a central system.

5. Yes, higher denomination machines do tend to have higher long-term paybacks than lower denomination machines. The pool of possible outcomes on the higher denomination machine has a higher long-term payback than on the lower denomination machine. The long-term payback is altered by either changing the pay table (which is how video poker paybacks are changed) or by changing the layout of the symbols on the virtual reels.

Remember, random does not mean that everything is completely unpredictable. The only thing random on a slot machine is the combination that will land on the payline next.

Best of luck in and out of the casinos,
John


Send your slot and video poker questions to John Robison, Slot Expert, at slotexpert@comcast.net. Because of the volume of mail I receive, I regret that I can't send a reply to every question.

John Robison

John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots
John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots