1. How Are Slot Machines Programmed To Pay Out
2. How To Win At Slot Machines
3. How Do Slots Machines Work
4. How Slot Machines Pay Out

Sorry about the delay since my last posting. I’ve been hard at work reading slot machine manufacturer specification sheets, and also playing the slots in my local casino – so that I can now bring you a list of slot machine payout cycles / volatility. I don’t believe you’ll find this information elsewhere! I researched it, I’ve prepared it (as I do with ALL content on this site) – so if by chance it ends up appearing somewhere else on the Internet going forward, remember where you saw it FIRST. Here!

To my mind there are three main types of slot machines. Those that have Frequent Hits and Modest Wins, those with Mid-range Hits and Medium Wins, and those with Less Frequent Hits and Larger Wins. I’ve arranged my list / tables with this in mind. I’ve considered slot machines from multiple slot machine manufacturers: IGT, Aristocrat, WMS, Bally, etc to try and provide a comprehensive listing. That said, I’m only featuring about 100 slot machines here – and there are many many thousands of slot machine varieties out there… still, it’s a start right?

The slots are programmed to keep a certain percentage of all the money put into them. Let us say that percentage is 10%, which means the machine will keep $10 for every $100 bet by the player thereby returning the rest of the player’s $90 in wins. Slot machines are programmed using Random Number Generator (RNG), which means slot machines are random and are games of luck. But, there is a way to win at slot machines, and here are 10 useful tips to help you win the game. Watch and enjoy:) 1.9K views.

If you’re a small recreational slot player, sticking with Frequent Hits and Modest Wins machines will lower your risk of going broke early. Middle of the road slot players with a few hundred dollars of bankroll might enjoy the Mid-range Hits and Medium Wins machines. Only serious / well bankrolled players should ideally play the Less Frequent Hits and Larger Wins slot machines – these are VERY volatile!

Enjoy the listing, and feel free to send me your comments or an email.

Slot machines with FREQUENT HITS and MODEST WINS
50 Lions
Black Rhino
Canary Riches
Heart of Gold
Incan Pyramid
Love Birds
Macaw Magic
Money Storm
Money Tree
Outback Jack
Ramses Prox
Where’s The Gold
Wild Cougar
Wild Goose
Wild Jungle

Slot machines with MID-RANGE HITS and MEDIUM WINS
Adonis
Aloha Magic
Arabian Jewels
Buccaneer
Corrida De Toros
Desert Gold
Dolphin Treasure
Geisha
Get Eggcited
Golden Canaries
Golden Gong
Golden Pyramids
Good Fortune
Grizzly
Helen Of Troy
Hollywood Dreams
House of Hearts
Jungle Jive
King of Neptune
King of The Nile
Koala Mint
LA Gator
Lucky Jack
Miss Kitty
Money Beans
Money Bears
Monkey In The Middle
Moon Festival
Moulin Nights
Musketeer
Mystic Mermaid
Nerds Gone Wild
Orchid Mist
Owl Capone
Oz Great Chase
Oz Jungle
Oz Lost City
Oz Safari
Panther Magic
Pelican Pete
Penguin Pays
Pot of Gold
Queen of The Nile
Rapid Riches
Return of the Samurai
Roll Up Roll Up
Seal The Deal
Show Me The Money
Spring Carnival
Super Stars
Superbucks 2
Superbucks 3
Superbucks 4
Sweet Hearts II
Triple Tigers
Venetian Nights
Viking Warrior
White Russia
Wicked Winnings
Wild Hearts
Wild Thing
Winning Streak

Slot machines with LESS FREQUENT HITS and LARGER WINS
5 Dragons
Anthony & Cleopatra
Big Ben
Brazil
Centurion
Choy Sun Doa
Crystal Springs
Dragon Lord
Dream Catcher
Fire Dancer
Fox On The Run
Genghis Khan
Golden Incas
Inca Chief
Inca Sun
Indian Dreaming
Island Delight
Kakadu Dreaming
Line King
Magician
Ms Foxy Fortune
Mystic Chief
Mystic Power
Peacock Magic
Phoneix Fantasy
Pompeii
Pride Of Africa
Queen Of Sheba
Red Baron
Star Drifter
Sun Queen
Temple Of Zeus
Tiki Torch
Water Margin
Whales Of Cash
Wild Africa
Wild Ways
Wings Over Olympus
Zorro

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.

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.

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.

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.

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.

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.

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

How Are Slot Machines Programmed To Pay Out

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.')

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.

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.

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:

How To Win At Slot Machines

'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.

How Do Slots Machines Work

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.

How Slot Machines Pay Out

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.