The RNG
There are many modern computerized slot machines. So the odds are whatever they are programmed to be. The reels and lever are present for historical and entertainment reasons only. A Random Number Generator determines the positions of the reels. The machine's software includes a Random Number Generator.
Random numbers are constantly generated by the RNG at an extremely high rate. When a player presses the Play button the most recent random number determines the result. That means that the result depends on exactly when the game is played. The result is different every fraction of a second.
The RNG was noticed to generate not exactly random numbers. The sequence of numbers is repeated by most of the RNGs. This behavior is due to poor programming. Pseudo RNGs with very long periods are relatively easy to build. No computer can complete a single period in the expected lifetime of the universe. The access to the pseudo RNG code and seed values was known to Ronald Dale Harris, a former slot machine programmer. Equations for specific gambling games like Keno were discovered by him. Then the prediction was made that the next set of selected numbers would be based on the previous games played. However, this is impossible for most machines, because the RNG picks numbers even when the machine is not being played. So the numbers can't be exactly found in a sequence.

Payout Percentage
The percentage of winnings paid out of the money that is wagered by players is 82–98 per cent. The term theoretical payout percentage is used to denote it. Jurisdictions serve to control the minimum theoretical payout percentage. Law or regulation typically establish it. Nearly each casino has its own winning pattern. It concerns the amounts they pay and the frequencies of these pay-outs. The main criterion for selecting the winning patterns on slot machines is that they should yield a certain fraction of the money played to the house. The rest of the money goes to the players.
At the factory when the software is written a slot machine's theoretical payout percentage is set. Changing the payout percentage after a slot machine has been placed on the gaming floor requires a physical swap of the software. Based on current technology, this is a time-consuming process and as such is done infrequently. Certain jurisdictions presuppose the EPROM to have a tamper-evident seal. To change it Gaming Control Board officials should be present. According to other jurisdictions slot machines are randomly audited to ensure that they contain only approved software.
The Nevada Gaming Commission is working now with Las Vegas casinos on technology that would allow the casino's slot manager to change the game, the odds, and the payouts remotely. Only after the selected machine has been idle for at least four minutes can the change be done. After making the change the machine is locked to new players for four minutes, it displays an on-screen message informing potential players that a change is being made.

Machines That Are Linked
Often machines are linked together in a way that allows a group of machines to offer a particularly large prize, or jackpot. If a player gets a specific combination of symbols the progressive jackpot from this group of machines is given to him. A single slot machine's jackpot is considerably less than the progressive jackpot.
There can also be multiple casinos consisting of multiple machines. In these cases, the machines may be owned by the manufacturer, who is responsible for paying the jackpot.

Near-miss Programming
The reel display of modern slot machines is controlled by computer software. That is why it is possible to make the slot machine frequently display combinations that are close to winning combinations.
The term near-miss programming is used to denote this practice.
There is a related phenomenon which is also called near-miss. Winning percentages programmed into the slot machine control the chance of a winning combination appearing on a pay line. The combinations above and below the payline are all roughly equally randomly distributed. This means it is much more likely that a winning combination will appear above or below a pay line than on the pay line. The occurance of this phenomenon is possible when abbreviated physical reels are used to display a win pattern based upon the RNG. The symbols that appear around the winning line in video slots are an accurate depiction of how the reels were mathematically modeled.
The issue of a near-miss above or below the pay line was also the subject of the Nevada Gaming Commission investigation. If the near-miss above or below the pay line was not specially programmed it was stated to be legal. That means that the possibility of near-miss occurrence should be equal to the possibility of any other combination. The machine cannot be specially programmed to show winning combinations more frequently than other combinations above or below the pay line.
In Australia near-miss programming, where a near miss is inaccurately displayed is not allowed either. Stop motion cameras are used by regulators for manufacturer's practices audit.

Slots Fraud
Sometimes mechanical slot machines and their coin acceptors seem to belong to cheating devices and other scams.
EPROM computer chips controls modern slot machines and coin acceptors have become obsolete in favor of bill acceptors. Different advanced anti-cheating and anti-counterfeiting measures have been taken to make it difficult to defraud these machines. Nowadays microwaves are used to defraud slot machines.

Here is the list of the most amusing myths concerning slots.
You can spot a winning slot machine.
The only way you'll spot a winning slot machine is when the bells are ringing and the money is dropping. RNG is the main element of every slot machine and one never knows what combination it will form.
Casinos place loose slots near the cashier, aisle ways, etc.
In reality it is not to casino’s advantage to place loose slots at one and the same place, because in this case gamblers would play only these slots. The slots are mixed and nobody can say for sure whether this slot is a loose one or not.
Count the number of symbols on the reels to determine your odds.
This is mathematically impossible, remember the RNG (random number generator) determines the stops. Thereare literally millions of combinations on a 3 reel slot machine, so there is no way of determining odds by the symbols on the reels alone.
Casinos can tighten or loosen slot machines from the back office.
It is not as simple as that. The casino can’t just change the chip of the slot machine. It is illegal and it has to be permitted by the commission.
A slot machine that has not been paying is due to hit.
Absolutely false. The RNG assures this. You have an equal chance of winning on a losing machine as you do on a machine that just paid out the jackpot.
Pulling the slot machine handle produces more wins than pressing the spin button and visa versa.
Again false. It makes no difference, as the computer only uses these as mechanisms to start the game. Only the computer determines a win or a loss and it has already determined if you are a winner or loser even before the first reel stops spinning.
Playing with hot coins improves your chances.
It is false. Nothing can affect the outcome, the machine doesn’t care and doesn’t know whether your coins are cold or hot.
Casinos set slot machines to payback more on the weekends.
Wrong again. Your odds of winning are the same no matter if it's 4:00pm Monday, 8:00pm Saturday or 3:00am Wednesday. Casinos can not and do not do this.

Slots are one of the oldest casino entertainments. Throughout the years, designs and implementation of slot machines went from mechanical to electronic, and from electronic to digital, then from digital to purely software, but the principles are still the same: the slot machine has reels which spin and, if the pre-defined winning combination plays out, you win. Basically, you just put in the coins and wait to find out whether you won or not.
In fact all slot machines are the same. They have different odds (and of course payouts), different payoffs, different symbols and different exterior arrangement, but there's little difference under the hood. There are so many variatisn of slot machines that everybody can find something to his liking.
Two most distinct types of slot machines are single line and multiline slots. As it can be understood from its name single line slots have only one line with 4 or 5 wheels. But multi line slots can have up to 25 lines. Multi line slots are more difficult to understand because you win according to the winning combinations on the paylines, which can be formed in many ways. It can happen that you win nothing during the game or that you win big in a short while. Paylines can be different. They can be vertical, diagonal, zigzags and what not.
Jackpot is also a feature peculiar not for all slots. If the slot machine has a jackpot it means that a certain amount of each additional bet is added to the jackpot. As the players wager, the jackpot grows and grows, sometimes crossing hundreds of thousands of dollars. There is only one winning combination that can bring the gambler the jackpot.
Slot machines are historically played with coins. Online casino slot machines are no exception to that rule, even though bets might differ slightly. Indeed, as well as with all small wager games, there are top bets - they're known as table limits in table games. Slots are the easiest casino games. They don’t require any decision on the player’s part.
Online slot machines also have RNG, which exclude any possibility to cheat. This methodic allows very fair and precise balancing without actually hurting neither the players' interests nor the casino revenue.

The US
In the United States the availability of slot machines is highly regulated by state governments. To regulate the possession and use of slot machines many states have established gaming control boards. There are no significant restrictions against slot machines in Nevada. New Jersey allows only hotel casinos operated in Atlantic City to have slot machines. Only licensed riverboats or permanently-anchored barges are allowed to have slot machines in some states. In Delaware there are slot machines only at three horse tracks. There is State lottery commission to regulate them.

Casinos: Native American
Slot machines are forbidden in Native American casinos located in reservations. When the tribe first reaches a pact with the state in which it is located it gets the permission to have them. Typically, a pact entitles the state to receive a fraction of the gross revenue from slot machines.

Slot Machine Classes
No federal law governs slot machines. Each state has its own classification. There are states where the usage of slot machines in a casino or other gaming area is restricted. "Class III" (or "traditional") slot machines operate independently from a centralized computer system. The possibility that a player wing any payout is the same with every play. Class III slots are most often seen in Nevada or Atlantic City. The term "Vegas-style slots" is iften used to denote them.
"Class II" slot machines ("video lottery terminals" or "VLTs") are connected to a centralized computer system. The determination of the outcome of each wager is fulfilled by it. Each machine has an equal chance of winning a series of limited prizes. The casino pays a fee to the state for each Class III game. The state doesn't regulate Class II games so tightly.

Class II Game Characteristics
The players are playing against each other. They are competing for a common prize. One player always wins the game. The game is continued until someone wins. In a given set there is a certain number of wins and losses. The combimation that has already occurred cannot occur again until a new batch is initiated. One game is dependent on previous games. The player must be an active participant. The same set of numbers is played by all players.

Class III Game Characteristics
The house plays against the player. There is no connection between the previous and the next games. Any possible outcome can occur in any game.

Clubs Of Slot Players
Many American casinos offer free memberships in "slot clubs". Complimentary food, drinks, hotel rooms, or merchandise are called comps and this is the way a small fraction of the amount of money that is bet is returned to the players. The requirement of such clubs is the usage of cards for the slot machines. Comps or "cash back" allows to make the differences in the maximum theoretical returns significant.

Australia
Queen of the Nile (manufactured by Aristocrat) is one of the most popular Australian poker machine games. Australian slot machines are called Gaming Machines. Australian-style gaming machines frequently use video displays to simulate physical reels. There are five of them in most cases. The laws regulating the use of gaming machines in Australia are a matter for State governments.
Gaming machines are found in casinos as well as pubs and clubs in some states. The first Australian state to legalize this style of gambling was New South Wales. In 1956 they were made legal in all registered clubs in the state.
The usage of particular forms of gaming machine is allowed in Western Australia.

Britain
In Britain slot machines are known as fruit machines, one-armed bandits and AWP. Pubs, clubs, arcades, and some take-away food shops have fruit machines. 3, 4 or 6 reels with around 16 or 24 fruit symbols printed around them can be found on the machines. These reels should be spun. The machine pays winnings if certain combinations of fruit appear. There is similarity between these machines and slot machines seen in casinos and elsewhere around the world. But there are some extra features. There exists a strict jackpot limit. The UK fruit machines have some features. A player may be given the opportunity to hold one or more reels before spinning. The chance of winning can sometimes be increased. A finite number nudges following a spin is given to a player. The term nudge is used to denote a single-step rotation of a reel of the player's choice.
The maximum payout for an individual game is different depending on the type and the location of the machine. There are "club machines" in private members' clubs. They have higher jackpots and are allowed to charge more per game.
These machines differ from American slot machines. The probability of getting the jackpot in each game is independent of any other game.
The AWP fruit machine is played in Europe and in countries such as the Czech Republic, Russia, and Ukraine.

Japan
The term pachisuro is used to denote Japanese slot machines. Their ancestor is the traditional Japanese pachinko game. Slot machines have appeared recently. There are slot machines in pachinko parlors and the adult sections of amusement arcades, known as game centers.
Regulation of the machines is fulfilled by IC chips. They have six different levels changing the odds of a "777". There are certain rules and regulations in spite of the many varieties of the machines.

There is a man who managed to cheat slots.
Slot machines pay on a random basis, but what if you could improve the payout a little? Would you do it? Tommy Glenn Carmichael would and did.
Tommy is now 53 and he can be said to have spent all his life inventing different devices to cheat slot machines. His first device was a kind of a top-button joint. By the way, for this device he was sent to prison. Upon his release, he continued to work on the problem and to devise a better way to cheat the new slot machines. His next invention was a slider, a guitar wire. He inserted it into the machine, which released coins form the hopper.
Later the slot machines were not any longer mechanical, they were computerized and as a result there appeared a need for a new device. In some way he managed to fool the manufacture who showed him the inner construction of a slot machine. It was enough to learn everything that he wanted. Carmichael invented what he called a “light wand. ” The wand, built with a camera battery and a bright miniature light, was used to shine into the slot machine and blind a sensor, causing the hopper to pay out coins. Carmichael marketed these wands to other slot cheats, making as much as ,000 a day. He drove expensive cars, took cruises, and bought two houses.
But good thing will end one day. While using his devise Tommy was caught by the police. He was fined, but soon came back to the same business. By this time, authorities had tapped his phone and recorded conversations with other cheats who used his device. Three years’ probation and expropriation was the punishment. He has been banned from entering any casino.