Joined: Mar 1, 2011
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March 1st, 2011 at 9:21:27 AM permalink
I am writing in trying to learn how video slot machines work. I found the Wizard of Odds articles about slot machines the most informative on the entire web as to how slots really work. Surprisingly (?) there is very little information available on this topic.

Specifically, I found your "How they work" article at

very useful, along with appendix 1 at

I realize the articles are referring to electronic slot machines, and aren't necessarily the same for video slots, although I would have to believe they share some concepts.

I have two questions: In regards to the multiple paylines supported by video slot machines, along with the relationship from the lookup table to the images that show up in the virtual reel on-screen.

Assuming a three reel slot.

With the virtual reels that appear for video slots, is it correct to assume that they are a simulated version of the "stepper slot" with 22 symbols on each reel, which are displayed in order and then wrap-around to the first one again?

1. I guess I don't understand how the lookup table relates to this virtual reel though.

Assuming the RNG returns three numbers between 1-64 which we then reference in the lookup table to come up with a possible win, what are the virtual reels doing? Do we just animate the sequence of images, and then stop the reels at the image which match what the RNG returned, after some predetermined time, such as a second or two?

Now is when paylines are introduced. The paylines work on the concept of the reel, so the winning on the second, third and whatever additional paylines are dependent on what is currently displayed on the reel, not the lookup table.

2. So, how does one calculate the odds for these additional paylines?

It seems like at this point the order of the symbols on the reels both become very important.

I realize the games you analyzed in the main article and in the appendix are two different games, and maybe shouldn't be inter-mixed.

However, I do notice in Appendix one, the second table "Double Strike Actual Results" shows symbols multiple times. Yet, in the main article, it says that after the lookup occurs, it is mapped to the symbol in the reel (paragraph 2 after "Lookup Table for Red White & Blue", second sentence)

From the article "For example, stops 60 to 62 on reel 1 all are mapped to a 1 bar symbol. These will all be directed to the same 1 bar symbol on the actual reel."

Yet, there are two single bar symbols on the reel in appendix 1. Which one does it get mapped to?

I am curious as to how these work. Thanks in advance to.

Joined: Aug 31, 2010
  • Threads: 88
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March 2nd, 2011 at 7:46:45 AM permalink
Multi-line video slots don't use weighted virtual reels. They just use really long reel strips, 48, 64, or longer. That's not to say that there aren't more of one symbol than another; just that each stop on the video "physical reel" is equally likely. That way, the RTP for each payline is the same.
"In my own case, when it seemed to me after a long illness that death was close at hand, I found no little solace in playing constantly at dice." -- Girolamo Cardano, 1563

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