Random Number Generator
Modern slot machines are computerized. The odds are programmed. The reels and lever are present for historical and entertainment reasons only. It is a Random Number Generator that chooses the reels positions. The machine's software includes a Random Number Generator.
The RNG is constantly generating random numbers at an extremely high rate. When a player presses the Play button the most recent random number determines the result. The result varies depending 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. Most RNGs will repeat their number sequence. Poor programming is its reason. Pseudo RNGs with very long periods canbe built relatively easily. The computer that is able to complete a single period in the expected lifetime of the universe hasn't been invented yet. Ronald Dale Harris, a former slot machine programmer, had access to the pseudo RNG code and seed values. Specific gambling games equations were discovered by him. They allowed to predict that the next set of selected numbers would be based on the previous games played. But it is impossible for most machines, because numbers are picked by the RNG even when no one plays. So the player cannot tell where in the sequence they are.

Percentage Of The Payout
Slot machines usually pay out as winnings 82–98 per cent of the money that is wagered by players. This payout percentage is called theoretical. Jurisdictions influence the minimum theoretical payout percentage. Law or regulation are used to establish it. A certain winning pattern exists nearly in every casino. The amounts they pay and the frequencies of these pay-outs are reflected in it. 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 players get the rest of the money.
A slot machine's software is written and the theoretical payout percentage is set simultaneously. To change the payout percentage after a slot machine has been placed on the gaming floor a physical swap of the software is required. It is done infrequently because this is a time-consuming process. There is sometimes a tamper-evident seal on the EPROM. Gaming Control Board officials should be called for changing it. Other jurisdictions constantly ensure that slot machines 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. The change cannot be done instantaneously, but only after the selected machine has been idle for at least four minutes. 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.

Linked Machines
Offering of a particularly large prize, or jackpot becomes possible when a group of machines is linked in a special way. If a player gets a specific combination of symbols the progressive jackpot from this group of machines is given to him. The amount paid for the progressive jackpot is usually far higher than any single slot machine could pay on its own.
In some cases multiple machines are linked across multiple casinos. In these cases the manufacturer owning these machines is responsible for paying the jackpot.

Near-miss Programming
Computer software controls the reel display of modern slot machines. That is why the slot machine can be programmed to display combinations that are close to winning combinations.
This practice is called near-miss programming.
This term is also used for a related phenomenon. The chance of a winning combination appearing on a pay line is controlled by the winning percentages programmed into the slot machine. The combinations above and below the payline are all roughly equally randomly distributed. There are roughly equally randomly distributed combinations above and below the pay line. This occurs if abbreviated physical reels are used to display a win pattern based upon the RNG. In video slot machines, virtual reels are used and the symbols that appear around the winning line are usually an accurate depiction of how the reels were mathematically modeled.
The issue of a near-miss above or below the pay line was also investigated by the Nevada Gaming Commission. It was considered to be legal as long as the near-miss above or below the pay line was not specially programmed. In other words, any other combination must be just as likely to occur as the near-miss. The machine can't show winning combinations more frequently than other combinations above or below the pay line.
Australia also forbids to use near-miss programming, where a near miss is inaccurately displayed. Manufacturer's practices are audited by regulators with the help of stop motion cameras.

Slots Fraud
Sometimes mechanical slot machines and their coin acceptors seem to belong to cheating devices and other scams.
Modern slot machines are controlled by EPROM computer chips and coin acceptors were changed for bill acceptors. They are designed with advanced anti-cheating and anti-counterfeiting measures and are difficult to defraud. Recent attempts at defrauding slot machines involve manipulating the EPROM, such as by directing microwaves toward it to disrupt its proper functioning.

There exist at least two types of slot players.
The first type is a persistent player.
This type of slots player is the one that believes the win is right around the corner. The machine can begin paying in any second.
The player will play until the machine pays out. He must have found a machine that haven’t paid for a long period of time or he has inserted to many coins and has got nothing. They know the next big win, or any win is due to pay out. They can’t leave the machine because as soon as they do it will burst forth and pay out large sums. Maybe it can really work if you have already spent thousands of dollars and have got nothing back. The machine will pay any way.
Many years ago in the case of the payout players touch the coins to check whether he coins were hot or cold. If the coins where hot then the slot machine had not paid out in a while and to the chaser this was good as the machine was do. In fact the coins could be hot only because of the numerous lights that heated the coins.
The second type of slot players is a chaser.
One can feel the atmosphere of comfort and trust between the machine and the player.

It seems that every type of activity has its own rules of etiquette, and playing the slots is no exception. First of all decide whether to deal or not to deal with this very slot machine. As a gambler you are sure to have faced such a problem: you want to go to the bar or to the restroom, but still want to keep this slot. How can other understand that your machine is in play? If you hang a coin cup over the handle of the slot machine it will mean that this slot is in play by you. Another signal is to place the coin cup on the seat. If you play in the casino that uses a cashless system you can just leave the jacket or one of your belongings on the seat. In your turn you should respect other players and never sit to a slot that is in play. It happens very often that a player leaves his card and walks away. If it happens to you, put the card on the top of the slot machine. The player will come back and find it easily. Now smoking is allowed in most of the casinos. So if you smoke respect other players and place the ashtray as far from other players as possible. Tipping the attendant that brings you the winning is one more etiquette rule. There are a lot of questions about the sum of a tip. In the case of a jackpot tip him with 0,5% of your jackpot.

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

Casinos: Native American
There are no slot machines 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. A pact entitles the state to receive a fraction of the gross revenue from slot machines.

Classes Of Slots
There is no federal law governing slot machines. Their classifications may vary from state to state. Some states have restrictions on the type of slot machines that can be used in a casino or other gaming area. "Class III" (or "traditional") slot machines operate independently from a centralized computer system. Every play has equal chances of winning any payout. There are a lot of Class III slots in Nevada or Atlantic City. The term "Vegas-style slots" is iften used to denote them.
There are "Class II" slot machines ("video lottery terminals" or "VLTs") which are connected to a centralized computer system. It determines the outcome of each wager. The chance of winning a series of limited prizes is equal for each machine. There is a fee for each Class III game that the casino has to pay to the state. The state doesn't regulate Class II games so tightly.

Characteristics Of Class II Games
The players are playing against each other. The prize is common. Each game has a winner. The game is continued until someone wins. A given set has 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 is an active participant of the game. There is the same set of numbers for all players.

Class III Game Characteristics
The player is playing against the house. The previous games don't influence the following ones. The outcome of any game is unpredictable.

Clubs Of Slot Players
In American casinos there are "slot clubs" the membership of wich is free. They offer to return a small fraction of the amount of money that is bet in the form of comps. The cards are used to insert into the slot machines in these clubs. Comps or "cash back" allows to make the differences in the maximum theoretical returns significant.

Australia
Queen of the Nile is a poker machine that is very popular in Australia. Australian slot machines are called Gaming Machines. Physical reels are stimulated by video displays in Australian-style gaming machines. There are usually five of them. There are laws regulating the use of gaming machines in Australia which are created by State governments.
Gaming machines are found in casinos as well as pubs and clubs in some states. New South Wales was the first state to legalize this style of gambling. In 1956 they were made legal in all registered clubs in the state.
In Western Australia only particular forms of gaming machine are used.

Slots In The United Kingdom
In Britain slot machines are known as fruit machines, one-armed bandits and AWP. Fruit machines can be met in pubs, clubs, arcades, and some take-away food shops. These machines commonly have 3, but can be found with 4 or 6 reels with around 16 or 24 fruit symbols printed around them. These reels should be spun. Winnings are paid from the machine if certain combinations of fruit appear. These are very similar to slot machines seen in casinos and elsewhere around the world. These games have lots of extra features. There exists a strict jackpot limit. There are some features of fruit machines in the UK. A player can hold one or more reels before spinning. It sometimes increases the chance of winning. A finite number nudges following a spin is given to a player. A nudge is a single-step rotation of a reel of the player's choice.
The maximum payout for an individual game is influenced by the type and the location of the machine. Private members' clubs are allowed to have "club machines". They have higher jackpots and are allowed to charge more per game.
These machines also operate in a different manner to 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
Pachisuro is the name for Japanese slot machines. The traditional Japanese pachinko game is their ancestor. Slot machines are new phenomenon. Pachinko parlors and the adult sections of amusement arcades, known as game centers have them.
The machines are regulated with 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.

Meet the man who beat the slots.
It is not a secret that it is next to impossible to cheat a slot machine. But do you know that Tommy Glenn Carmichael managed to improve the payout of the machine to his benefit.
Tommy is now 53 and he can be said to have spent all his life inventing different devices to cheat slot machines. He was caught with one, called a top-bottom joint, and sentenced to prison. Then he was released, but continued to work at inventing devices for cheating a slot. The principle of his next invention was following: he inserted a guitar wire in the slot machine and it made the coins release from the hopper.
When the slots were computerized he needed a new tool. Tommy found a manufacture who showed him the inside of a slot machine. From that experience, he learned what he needed to know to beat it. 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. He sold these wands and could earn up to ,000 a day. He drove expensive cars, took cruises, and bought two houses.
But as known good things can’t last forever. Tommy was caught using his invention in one of the casinos. While charges from that incident were later dropped, he was caught under similar circumstances in Laughlin and later Atlantic City. By that time the police already have all necessary clues to prove that Tommy was guilty. He got three years’ probation and lost everything that he had bought before. He has been banned from entering any casino.