Slots - Cycles and other myths

Reason #3 why the Wizard likes Bovada: Excellent Odds

In my opinion many online casinos are too stingy when setting the odds on their games. They think they will make more money that way but I believe they are misguided, because when players lose too quickly it's not fun, and those players might not come back.

Bovada is one of the few casinos that understands this. They offer generous odds to let you play longer and get you a better chance of winning. Among their generous offerings are Full-Pay Jacks or Better returning 99.54%, five other video poker games paying over 99%, single-zero roulette, and my favorite, Double Jackpot Poker, returning 99.63%!

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In "how slot machines works" you mention that the Random numbers (1 to 2+ billion) are drawn in a cycle to ensure each number is chosen once per cycle. Are you saying that the slot has a 2+ billion-element table that gets filled with all the possible numbers (over time)? Is this why a slot machine will sometimes hesitate (as if it's "thinking" for a few seconds before allowing you to initiate a play... because it's filled the "random number table" and is re-initializing it for another round? I have always wondered about these periodic (after maybe around 30-50 pulls) "hesitations" that slot machines exhibit; because my observations are that the pay/take characteristics of a slot machine seem to change between these "hesitations." Frequently, I have seen a slot that was in a "pay cycle" (for lack of better words) go suddenly cold after going through this hesitation. Conversely, I have seen cold machines suddenly start paying more after this hesitation occurs. Whatever! The exact reason for this "pause" it seems clear the machine is re-initializing or re-loading something... I just don't know what it is.

Scott from Leawood, USA

No, the machine does not have a huge element table of over two billion elements. The random number generators choose each number once in the cycle using mathematical algorithms and do not need to keep track of which numbers were already chosen. Regarding the pause, it has nothing to do with how much it is going to pay. I think the game does some internal auditing from time to time. There is no such thing as hot and cold cycles with slot machines. The ups and downs are just normal random variation.

I play a machine in Atlantic city Called "Reel Detectives". I have read your informative article on how slot machines work and I have a good understanding of the programming behind them. what I don't understand is how on some days these machines will pay almost an exclusive combination of seven wins with no jackpots all day and yet other days it will pay jackpots all day with little to no seven wins.

If the machine is truly picking random combinations wouldn't the prize distribution be more random. It's as if IGT programmed the machine to have "Planned Cycles" to make the game more interesting to play. I know your going to say that these are just random events, but it is extremely unlikely that a machine will only pay mid and lower tier prizes all day and omit the jackpot and vice-versa and do this over and over again. HOW are these WEIGHTED cycles explained? Also if you could point me to any books you recommend on the programming of slot machines I would appreciate it.

James from Cherry Hill, U.S.

These are just random events. The laws of probability dictate that some days will be dry with a few big winners and others will have a lot of lower payouts. Most days will have a balanced mix and these days are always the first forgotten by the player. There is no switch the casino is throwing to alter the mood of their machines. I tend to think you're just remember what you want to in order to substantiate your theory.

Considering that a slot machines random number generator is fixed to supply the selected numbers to the virtual reel stops, and in turn are tied to the actual reel stops, is it not possible for the casino computers to swap non-winning stops to win stops, thus increasing the win percentage. This would maybe explain why all machines on some carosels seem to get hot at the same time, then all revert back after drawing a croud of players...just wondering...your site is a great information site...thanks


No, this does not happen. How much the slot machine pays is determined by a microchip called an EPROM, which is generally left alone. To change it, at least in Nevada, the casino would have to get permission from the gaming authorities. Even without permission, they would have to open up each machine and change the EPROM by hand.

I speculate that the reason for what you observed about all the machines on a carousel getting hot at the same time is due partially to chance, partially selective memory, and partially to a snowball effect where players will gravitate to an area where they hear a lot of winning and simply add to the number of wins because of more players.

Your explanation of virtual versus physical slot machine reels was most informative.

  1. Given the random number generator stops on a virtual Cherry say, how does the machine make the physical reel stop on a visible cherry? I mean technically speaking.
  2. Does this explain how pachinko machines from Japan can electronically alter payout percentages without altering the physical reel symbols?
  3. Suppose the machine decides its time for a BAR, the only BAR on the third reel, just as one passes the pay-line. Does it let the reel go one full turn and catch it on the next go-round?
  4. Suppose a physical reel stops on a paying combination by mistake, i.e. a symbol other than the virtual one pre-ordained. What happens then?

Thanks much.

Larry H. from Redwood City, California

Let me answer each question individually.

  1. It is just programming code that dictates to the machine that if the virtual reel stops on a cherry to make the actual reel stop on a cherry. There are actual notches on the reels which may help the machine to stop in the right place. If you peer through the glass at and angle you can sometimes see these notches. However, I am not an engineer and am not sure exactly how the machine knows to stop at just the right moment. It just take it for granted that it can.
  2. Theoretically, the casino could change the payout on a slot machine with just a remote control. The remote control could tell the machine to use any previously programmed virtual reels. Practically speaking, the major casinos need to get approval from the gaming authorities to change the payback of a machine. If they did get such authorization all a slot technician has to do is replace a chip inside the machine, known as an e-prom. This happens infrequently and would not warrant the expense of a remote control.
  3. It seems to me the reels spin at least several times before stopping.
  4. In the unlikely even that happened, then I think it would trigger a malfunction and the bet would be voided.

This happens to me 100% of the time: A slot will pay out normally to start and then after about a half hour’s consistent play, it will produce a declining win pattern, and an increasing lose pattern. Once I hit $20.00 in my account balance, the losing pattern will intensify to sometimes 20 straight loses in a row. (This is on a 5 reel, 9 line slot). I can almost sense when the slot goes into this "mode". I hardly think it is fair to flag an account due to prolonged play. Is this a programming ploy to prevent large wins that would normally come after consistent play on the same slot and to get you to make that next deposit?


I will say that for class 3 slots by major slot makers like IGT, Bally, and Williams do not resort to these sort of tricks. With respectable slot machines every play has the exact same probability of winning. If you don't believe me then why don’t you go from machine to machine playing each one for half an hour.

How often does a casino change the percentage on a slot machine?

Nathan from Marquette, Michigan

Not often. Contrary to popular myth the casinos don’t tighten the machines on weekends or whenever it is busy. Here in Las Vegas the casinos have to fill out a form every time they change the percentage on each game. Most slot managers I have spoken with have a policy on what coinage is set to what return. I tend to think the most likely reason to change the percentage would a change in ownership and/or management, which do not happen often.

When playing video poker will it decrease my odds of winning if I put a $50 bill in, instead of $5 or $10 increments?

Karen from Eastchester, New York

No. Neither the amount you put in nor the denomination affects the odds. The same is true of slots.

Wizard, what do you think about the new "server based" slot machines currently being tested at Barona Valley Ranch? Apparently this technology allows the casino to instantly change the machines from their back offices - including the games offered, denominations, and.....the payouts! I think this is going a bit far. I mean what’s to stop the house from targeting certain players (like the drunk high roller) and making it tougher for that player to win? We all know the casinos can pretty much keep an eye on any player they want any time. Between the surveillance and now this technology it seems to give the house too much of an edge. Suppose a table player has a heated disagreement with a dealer or pit boss over a hand (which occasionally happens); now this same player goes to the slots and the house can extract revenge by making his machine pay out less??!! Of course they could "favor" certain players too...which could be just as dangerous. I’m all for allowing the games and denominations to be changed, but shouldn’t the regulators be involved when it comes to payout percentages???

Gary from Charlotte, NC

From what I hear anything you can configure at the machine you can configure remotely through the server. This would include the theoretical return percentage. However most casinos report that changing the theoretical return of a slot machine necessitates a lot of paperwork.

Even if it were effortless to move the slot machine return up and down, it strikes me as a conspiracy theory to think the casinos would do that on a player by player basis. Living here in Vegas, I hear all kinds of theories about the lengths the casinos go to in order to win, like pumping in oxygen and playing a subsonic mantra that says "lose lose lose." These are just urban legends. Most casinos correctly believe that if you give the player a good experience and a fair gamble then he will keep coming back. As they say, you can only slaughter a sheep only once, but you can shear it many times. (My webmaster, Michael Bluejay, who is a vegetarian, tried to get me to use this analogy instead: "You can seize all of a sheep’s money only once, but you can force it to take you bowling many times.")

Wizard, what do you think about the new "server based" slot machines currently being used at the Treasure Island in Las Vegas? Apparently this technology allows the casino to instantly change the machines from their back offices — including the games offered, denominations, and.....the payouts! I think this is going a bit far. I mean what’s to stop the house from targeting certain players (like the drunk high roller) and making it tougher for that player to win? We all know the casinos can pretty much keep an eye on any player they want to any time. Between the surveillance, and now this technology, it seems to give the house too much of an edge. Suppose a table player has a heated disagreement with a dealer or pit boss over a hand (which occasionally happens); now this same player goes to the slots and the house can extract revenge by making his machine pay out less??!! Of course they could "favor" certain players too...which could be just as dangerous. I’m all for allowing the games and denominations to be changed, but shouldn’t the regulators be involved when it comes to payout percentages???

Gary from Charolotte, NC

I asked a source of mine who works at one of the casinos that utilize this technology. Besides the Treasure Island, this technology is also used at casinos in California, Michigan, and Mississippi. Here is what he said,

"Nothing can be changed if there are credits on the game. The slot machine will always reject any changes sent when there are credits on the meter. In Nevada, the machine also has to be idle for four minutes prior to and following any changes. It’s also not completely transparent to anyone standing in front of the slot machine. A black window pops up that says ’Remote Configuration In Progress’ (or something like that).

We mainly use ours to change the available denominations on our games. Similar to how table games will raise minimum bets on when the casino is busier, we will remove lower denominations on Friday morning and return them on Monday morning."

So, rest assured, that the slot manager can not tighten up a game on you just because he doesn’t like you. As long as you have credit in the game, nothing can be changed.

My wife and I are regular slot machine players, and have noticed that when a new slot machine gets into a casino, the "good hits" or payouts from hits, or bonus games seem to be much more frequent. Once the game "draws you in," so to speak, then it seems like it shuts down, and the hits and bonus rounds are less frequent. Can a casino legally put controls on how much a machine hits or enters into a bonus round?

Les from Fallbrook, CA

If you are implying the casino is changing the odds of the game while you're sitting there playing it, then I would say that is just a myth. To change the odds of a game, the slot maker would have to open up the game and change the EPROM chip. With server based game, where this can be done remotely, regulations require that the game be unplayed for a certain number of minutes before any changes can made.

If you are implying that the casino sets a slot machine loose for the first so many days, to draw new players, and then switches the EPROM to a stingier one, then I would disagree as well. That could easily be done, and legally, but I doubt it is. In my slot machine survey I found that any given casino was fairly consistent in how loose or tight they set their slots.

Since the introduction of server based control of slot machines, has anyone tracked the best day and time to play slots? This last year I have unofficially noticed slots appear to pay better on Friday and Saturday night and awful on Friday morning and all day Sunday/Monday. My understanding is that slot machines are now controlled via a main server and not individual chips manually inserted/replaced by a slot tech. I keep thinking the casinos are trying to encourage play when people come to town and take the money back on Sunday and Monday before they leave.


For the benefit of other readers, the way slot machines have usually work is that a chip inside the machine, called an EPROM chip, determines how loose or stingy the machine is. The vast majority of slots today still function this way. Contrary to popular myth, slots don’t achieve their desired return percentage by paying more when the actual return is too low and less when it is too high. Rather, it is just subtle changes in the reel stripping on video slots and the virtual weights on stepper slots. It is usually up to the casino manager which chip to put in. Some jurisdictions leave that decision up to the state. A common myth about these slots is that the slot manager can flip a switch in his office and cause any slot machine, or all of them, to pay more or less. The truth is a slot technician has to open up the machine and physically change the EPROM chips.

However, with the new generation of "server-based slots," the myth has potential to be a reality. Slots on this system can indeed be controlled remotely. The slot manager is now able to change the theoretical return, pay tables in video poker, denomination, as well as the entire game, in the comfort of his own office. Here in Nevada there are safeguards to prevent abuse of this power. The Gaming Control Board has the following regulation:

"The conventional gaming device or client station must be in the idle mode with no errors or tilts, no play and no credits on the machine for at least 4 minutes. After this time, the conventional gaming device or client station must be disabled and rendered unplayable for at least 4 minutes. During the time the machine is disabled a message must be displayed on a video screen or other appropriate display device notifying the patron that the game configuration has been changed." — Technical Standards for Gaming Devices and On-line Slot Systems 1.140

So the slot manager couldn't tighten up the game you’re playing just because he didn't like your polka-dotted hat. However, in theory, he could loosen or tighten every machine that wasn’t being played. To finally get at your question, would he loosen and tighten the slots like a yo-yo depending on the time of day or day of the week? On my forum, I argued that would be bad business, but many who submitted comments disagreed with me. To help argue my side, I asked Nick Dillon, Executive Vice President/Assistant General Manager at the Barona Casino in San Diego County about it. Here is what he wrote back.

"The concern with SBG (server-based games) is that the manufacturers and most casinos are looking at it mostly from a cost savings (less slot techs/labor needed to convert games, etc) perspective. At Barona, we really only want it if it proves a true value to the player. We have approximately 80 units on the floor that we began testing a couple of years ago. We are not yet at the point where we can say there is a true benefit to the player. We have tested many aspects of these games but have never raised/lowered the hold based on time of day, day of week, etc. We have, however, tested some other things. One is changing the minimum denom based on day of week (penny during the week moved to nickel on the weekend, for example). The idea being the same as table games whereby the denom (table minimum bet) moves higher when demand is peaking. This maximizes revenue. However, we found that was not the case with our test (likely because tables are limited and full capacity during the increase, but slots generally are not, and because a “penny” player can actually be a “dollar” player regardless of what min denom he is playing). We found more dismay from guests that were used to finding their preferred game/denom and that it was now changed. We also tested changing only the default denom from penny to nickel. This is the denom that shows on screen when the game is idle. The majority of players may not be aware of multi-denom and play the default the majority of time. Again, we found no real difference in revenue.

As evidenced by our Loose Troop and Manufacturers Best programs, best blackjack rules, loosest video poker, no ATM fees, etc. we truly believe the player deserves the best gamble he can get. We feel that providing the longest play time for the dollar is the best strategy we can employ. There is no need to play with hold percentages and adjusting them 1-3 points either way for a day or two. Of course, a Strip property may feel differently as they only have a limited amount of time to win the money.

We are hopeful that we can help push the manufacturers to continue to develop SBG in favor of the player. We are hopeful that a player can put his player card in and his preferred games, denoms, etc will appear for his enjoyment at whatever device he sits. There are so many opportunities for this to be a great product for the player, which we believe will be good for our casino and the industry. If cost savings also come, great, but that should not be the main focus of a product like this." -- Nick Dillon

In conclusion, I think you are safe playing server-based slots. If you don’t believe me, keep an eye on the video poker pay tables. If you don’t see those going up and down on a daily basis, chances are the slot returns are being left alone as well.

This question was raised and discussed in the forum of my companion site Wizard of Vegas.

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