Inner workings of modern slots

I’ve been trying to get a grasp on the inner workings of slot machines in terms of how they turn random numbers into the things you see on screen.

For 3 reel slots with one payline this is very simple: if for instance there are 72 virtual stops and 18 physical stops, then each number 1-72 maps to one of the 18 physical stops, with of course the high paying symbols only having one virtual stop and the blanks having many.

Where I get lost is the new five reel, 3 row slots with like 20 paylines. Is each square its own independent event? The spinning reels seem to contradict this, showing symbols moving together. Does each of the 5 reels simply have a ton of symbols strung together, with the odds determined by the ratio of the symbols? This seems like it would be super hard to calculate expected value for multiple paylines because now each payline is no longer an independent event (like for instance if there is no where on the big reel strip where 3 wilds appear in a row, then if you get a wild in two paylines you cannot possibly get one in the third).

Any insight into modern slots that help me grasp the odds would be greatly appreciated!

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.

If I'm understanding your question correctly, it's simply a virtual reel and to evaluate, the manufacturer loops through every combination. You might like to go over to www.wizardofodds.com and look up the Atkins slot machine. The Wiz walks you through how to evaluate a modern virtual reel machine like you discuss.

That atkins deep dive helped quite a bit!

So it seems like I pretty much was correct in that each reel has a long strip where the symbols are always in the same order, and the odds are based on the ratio of the symbols.

To calculate return it seems like the wizard just tried every combination and then tallied up each combination’s win for all 15 paylines? And then bucketed those based on symbols and pays so like “in 1,024 of the 33,554,432” combinations, when looking at all 15 paylines, two Atkins symbols appeared in the first two columns”. Is that pretty much it? Most if not all modern slots work this way? Or is there other trickery depending on the specific machine?

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
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I am interested to hear about as much on this as anyone is willing to tell me, public or private.

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
link to original post

Is that even legal on a Class III machine? I know that it used to be that each reel had to be independent of the others - otherwise the manufacturer could set it up so an excessive number of "jackpot...jackpot...off by one" results could appear.

DRICH correct me if im wrong but its VERY simple

on ANY of the reels there are X stop positions... if there is 100 then the RNG picks a random number between that

the way to make this unpredictable, fair, and actually random is that when the RNG picks a number the number is SO big you wouldnt have a chance in hell to predict that number and then its "scaled"

what is scaling? well the number chosen by the RNG is so big it has to be "turned" into a smaller number or something in the range of whatever the number of stops are on the reel

how do you "turn" the number into a smaller number? all numbers on a computer are binary so say we have picked the number

123062971261695602299259482495664888722 or in binary
01011100100101010001000011101110100010011111110100000010011000110100010011111110110111001110101111100000100101011001101110010010

and the scaling works like if you were to only take the first 8 digits
01011100
we get the number 92

it does that FOR EVERY reel

Quote: ThatDonGuy

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
link to original post

Is that even legal on a Class III machine? I know that it used to be that each reel had to be independent of the others - otherwise the manufacturer could set it up so an excessive number of "jackpot...jackpot...off by one" results could appear.
link to original post

it works like that in every game not just slots

in order to create the visualizations of the win or loss you need to know if the person has won or lost before you tell them they did or not

I think this is a different question and yeah if I were to program a slot machine it would be somethin like:

1. Choose the random numbers
2. Calculate the win
3. Display the win

I don’t think there’s anything wrong with this, as long as step 1 and 2 are honest using 5 independent reels in the way the Atkins example does.

I think what could be an open question is if any slot machines for example decide yes or no to winning a bonus game let’s say with a 1/100 chance. If yes, it displays 3 coins on screen in random positions. This would contradict the odds you could calculate if you know the composition of the reels and each reel is truly independent. This is one of my main questions: do modern slot machines truly act as independent random reels, and how do those reels translate their random numbers to what you see.

In the Atkins example, there are 32 stops and each stop corresponds to numbers 1-32 randomly chosen. I wonder if some slot machines are biased where it may actually choose a number between 1-65, with 33 stops, if the number it chooses is 65 it goes to stop 33 (best symbol). Otherwise it divides it by 2 to convert to the stops 1-32.

With 3 reel slots and one payline I know they do this (map a larger virtual space to a smaller physical space), but do 5 reel games with very long “reel strips” do this too? Or do most always map each stop 1:1 and there are just a ton of symbols on each strip?

Quote: Theguyoverthere

I think this is a different question and yeah if I were to program a slot machine it would be somethin like:

1. Choose the random numbers
2. Calculate the win
3. Display the win

I don’t think there’s anything wrong with this, as long as step 1 and 2 are honest using 5 independent reels in the way the Atkins example does.

I think what could be an open question is if any slot machines for example decide yes or no to winning a bonus game let’s say with a 1/100 chance. If yes, it displays 3 coins on screen in random positions. This would contradict the odds you could calculate if you know the composition of the reels and each reel is truly independent. This is one of my main questions: do modern slot machines truly act as independent random reels, and how do those reels translate their random numbers to what you see.

In the Atkins example, there are 32 stops and each stop corresponds to numbers 1-32 randomly chosen. I wonder if some slot machines are biased where it may actually choose a number between 1-65, with 33 stops, if the number it chooses is 65 it goes to stop 33 (best symbol). Otherwise it divides it by 2 to convert to the stops 1-32.

With 3 reel slots and one payline I know they do this (map a larger virtual space to a smaller physical space), but do 5 reel games with very long “reel strips” do this too? Or do most always map each stop 1:1 and there are just a ton of symbols on each strip?
link to original post

well i think that spinning into a bonus round works like what i said... now i will try to find the thread but the bonus rounds are where the "funny" business can "kind of happen" IMO

the bonus rounds can have pre chosen wins and the symbols you chose may have no effect on the outcome... so if you see a bunch of symbols and lets say theres jackpots behind them ... mini grand etc... the RNG chooses the outcome and hides it and whatever one you pick is the one that was chosen by the RNG... seems shady but from what i understand completely legal ....

give me a second i need to find the thread

also keep in mind were talking about regulated slot machines... the things you are talking about are all possible most likely in jurisdictions that arent regulated...

https://wizardofvegas.com/forum/gambling/slots/38161-are-bonus-rounds-pre-calculated/

Quote: heatmap

Quote: ThatDonGuy

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
link to original post

Is that even legal on a Class III machine? I know that it used to be that each reel had to be independent of the others - otherwise the manufacturer could set it up so an excessive number of "jackpot...jackpot...off by one" results could appear.
link to original post

it works like that in every game not just slots

in order to create the visualizations of the win or loss you need to know if the person has won or lost before you tell them they did or not
link to original post

Maybe I misunderstood what was meant by "a corresponding display is generated." Yes, a result is generated, then a payout is calculated, then the result is converted into the symbols that appear on the screen, but what I am saying is, the machine does not do something like, "65% of all possible results are losers, so if I pick a number from, say, 1 to 1,000,000 and it's between 1 and 650,000, then I can just arbitrarily create a losing symbol screen and display it"; instead, result 1 has a particular screen, result 65,394 has a particular screen, result 334,392 has one, and so on.

Quote: ThatDonGuy

Quote: heatmap

Quote: ThatDonGuy

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
link to original post

Is that even legal on a Class III machine? I know that it used to be that each reel had to be independent of the others - otherwise the manufacturer could set it up so an excessive number of "jackpot...jackpot...off by one" results could appear.
link to original post

it works like that in every game not just slots

in order to create the visualizations of the win or loss you need to know if the person has won or lost before you tell them they did or not
link to original post

Maybe I misunderstood what was meant by "a corresponding display is generated." Yes, a result is generated, then a payout is calculated, then the result is converted into the symbols that appear on the screen, but what I am saying is, the machine does not do something like, "65% of all possible results are losers, so if I pick a number from, say, 1 to 1,000,000 and it's between 1 and 650,000, then I can just arbitrarily create a losing symbol screen and display it"; instead, result 1 has a particular screen, result 65,394 has a particular screen, result 334,392 has one, and so on.
link to original post

you are correct ... although i think thats a very simple way of describing VLTs in a way... whats odd is that i am pretty sure thats how "lightning link" jackpots work they call that 1 - 1000000 a "band" and its split into two "bands" that constitute winning or losing numbers

I know the Wizard said he’s designed or consulted on slot machines, I wonder if he could chime in to clarify if all slot machines that depict reels actually use reel strips (regardless of how long they are, they are still one continuous reel) that maybe sometimes are augmented with extra wilds, etc for some of the fancier games?

Or are some slot machines doing other things such as deciding “1/100 chance of a bonus, if yes then show 3 bonus symbols” rather than each symbol just being an option on a continuous strip?

Quote: Theguyoverthere

I know the Wizard said he’s designed or consulted on slot machines, I wonder if he could chime in to clarify if all slot machines that depict reels actually use reel strips (regardless of how long they are, they are still one continuous reel) that maybe sometimes are augmented with extra wilds, etc for some of the fancier games?

Or are some slot machines doing other things such as deciding “1/100 chance of a bonus, if yes then show 3 bonus symbols” rather than each symbol just being an option on a continuous strip?
link to original post

I would say Class III machines such as you see in Vegas use reel strips. Meaning that reels are created with payback such that the machine turns a profit in the long run. The manufacturer simply runs through every possible combination of reels.


Class II machines such as the bingo machines at NA casinos and the video lottery terminals pick an answer and then choose a combination that gets you to the answer.

My educated guess is that each reel has a fixed number of slots (not all reels have to have the same size) and five random numbers are chosen for the reel positions. Then, as been said, the loss/win is calculated, and the spinning/display made. Where a bonus is achieved, I don't know, but can imagine it picks a win value and goes through a bonus game, to achieve that value. (It's possible that it may do things like 10 free spins randomly, but I noitice they tend to be spicier than regular spins, so suspect it creates a series of wins to obtain the desired result.)

Compensated machines work differently, some have suggested they just respin if the win is too much or just pay/allow a jackpot if it's paying too little.

Quote: charliepatrick

Where a bonus is achieved, I don't know, but can imagine it picks a win value and goes through a bonus game, to achieve that value. (It's possible that it may do things like 10 free spins randomly, but I noitice they tend to be spicier than regular spins, so suspect it creates a series of wins to obtain the desired result.)

Class III machines clearly have to state that bonus reels are in play. So they work the same as the regular spins, but just have a higher EV.

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
link to original post

That is not true.

Quote: Theguyoverthere

I know the Wizard said he’s designed or consulted on slot machines, I wonder if he could chime in to clarify if all slot machines that depict reels actually use reel strips (regardless of how long they are, they are still one continuous reel) that maybe sometimes are augmented with extra wilds, etc for some of the fancier games?

Or are some slot machines doing other things such as deciding “1/100 chance of a bonus, if yes then show 3 bonus symbols” rather than each symbol just being an option on a continuous strip?
link to original post

In general the reels determine the outcome, not the other way around. In some games, like Ocean Magic, other factors, like a rising bubble, override some positions on the reels. There is other gaffing that goes on, but it is the exception, not the rule.

Quote: Wizard

Quote: UP84

For most new slots the reels are irrelevant. The slot's RNG and program first determine the outcome, and then a corresponding display is generated.
link to original post

That is not true.
link to original post

Thanks! I stand corrected then.

Quote: Theguyoverthere

I think this is a different question and yeah if I were to program a slot machine it would be somethin like:

1. Choose the random numbers
2. Calculate the win
3. Display the win

I don’t think there’s anything wrong with this, as long as step 1 and 2 are honest using 5 independent reels in the way the Atkins example does.

I think what could be an open question is if any slot machines for example decide yes or no to winning a bonus game let’s say with a 1/100 chance. If yes, it displays 3 coins on screen in random positions. This would contradict the odds you could calculate if you know the composition of the reels and each reel is truly independent. This is one of my main questions: do modern slot machines truly act as independent random reels, and how do those reels translate their random numbers to what you see.

In the Atkins example, there are 32 stops and each stop corresponds to numbers 1-32 randomly chosen. I wonder if some slot machines are biased where it may actually choose a number between 1-65, with 33 stops, if the number it chooses is 65 it goes to stop 33 (best symbol). Otherwise it divides it by 2 to convert to the stops 1-32.

With 3 reel slots and one payline I know they do this (map a larger virtual space to a smaller physical space), but do 5 reel games with very long “reel strips” do this too? Or do most always map each stop 1:1 and there are just a ton of symbols on each strip?
link to original post

Almost all of the older slots use the same reels each spin. There are large numbers of newer slots that use different sets of reels for each spin. As long as there is no 'secondary decision', this conforms to the regulations.

The probabilities for various combinations are rather inflexible when immutable reels are used. If the reels can be changed for every spin, then the game designer has a lot more control over the volatility and player experience (the fun factor). If you want to make three-of-a-kind rare for a certain symbol but still have four and five of a kinds appear not that much less frequently, you can achieve this by adding many more of the special symbols to the reels for some subset of the spins. The resulting games are also very hard to reverse engineer.