The RNG
There are many modern computerized slot machines. So the odds are whatever they are programmed to be. In modern slot machines, the reels and lever are present for historical and entertainment reasons only. The positions of the reels are chosen by a Random Number Generator. The machine's software includes a Random Number Generator.
The rate of generating random numbers by the RNG is extremely high. 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. A fraction of a second earlier or later, and the result would be different.
The numbers generated by the RNG seem to be not exactly random. It turned out that The number sequence is repeated time after time. Poor programming determines such behavior. It is relatively easy to build pseudo RNGs with very long periods. No computer can complete a single period in the expected lifetime of the universe. It was Ronald Dale Harris, a former slot machine programmer, who knew the pseudo RNG code and seed values. Equations for specific gambling games like Keno were discovered by him. They allowed to predict 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 player cannot tell where in the sequence they are.

Payout Percentage
Winnings 82–98 per cent of the money that is wagered by players are typically paid out by slot machines. This payout percentage is called theoretical. The minimum theoretical payout percentage is controlled by jurisdictions. Its establishment refers to the sphere of law or regulation. A certain winning pattern exists nearly in every casino. It contains the information about 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. As for the rest of the money it goes to the players.
When a slot machine's software is written its theoretical payout percentage is also set. Changing the payout percentage after a slot machine has been placed on the gaming floor requires a physical swap of the software. As it is a time-consuming process it is done infrequently. In certain jurisdictions the EPROM has a tamper-evident seal. Gaming Control Board officials should be called for changing it. Other jurisdictions randomly audit slot machines 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. The change cannot be done instantaneously, but only after the selected machine has been idle for at least four minutes. The machine must be locked to new players for four minutes and display an on-screen message informing potential players that a change is being made after the change is made.

Linked Machines
A group of machines offers a particularly large prize, or jackpot if they are linked together in a special way. Each slot machine in the group contributes a small amount to this progressive jackpot, awarded to a player who gets a specific combination of symbols. 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. The machines are then owned by the manufacturer, who is responsible for paying the jackpot.

Near-miss
Computer software controls the reel display of modern slot machines. It is possible to make the slot machine frequently display combinations that are close to winning combinations.
This practice of showing combinations that are similar to winning combinations more frequently than would occur randomly 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. However, the combinations appearing above and below the pay line 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. This phenomenon only occurs where abbreviated physical reels are used to display a win pattern based upon the RNG. Video slot machines have virtual reels 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 the subject of the Nevada Gaming Commission investigation. So long as the near-miss above or below the pay line was not specially programmed it was recognized legal. The near-miss and any other combination should have the same possibility of occurrence. The machine can't show winning combinations more frequently than other combinations above or below the pay line.
In Australia the usage of near-miss programming, where a near miss is inaccurately displayed is also illegal. Manufacturer's practices are audited by regulators with the help of stop motion cameras.

Slot Machines Fraud
Mechanical slot machines and their coin acceptors were sometimes susceptible to cheating devices and other scams.
EPROM computer chips controls modern slot machines and coin acceptors have become obsolete in favor of bill acceptors. These machines and their bill acceptors are designed with advanced anti-cheating and anti-counterfeiting measures and are difficult to defraud. One of the recent attempts at defrauding slot machines is directing microwaves toward it to disrupt its proper functioning.

As you know there are different types of slot machines. And do you know that there are even types of slot palyers.
The first type is a persistent player.
The players of this type believe that very soon there will be a period when the machine begins to pay. Just a second and the coins will be flying all over the casino!
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. Makes sense if you have lost 0. 00 and have yet to win. The machine can’t but paying.
In the old days when a payout occurred players would feel the coins to see if they were hot or cold. If the coins were hot they believed that the machine had not paid for a long period of time. The heat of the machines lights, etc would eventually heat 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.

Slots Rules: Understanding the rules of the game is always important, no matter what game you are playing. With slots the rules are very simple: Read the payout chart, insert coins, push button, (or pull handle), insert more coins. If you hear bells ringing and see lights flashing it means that you win. Of course you can win much, but never bet or spend more than you can afford.
Rules for playing Slots
Only slots have so simple rules. In fact it is so because there are no rules at all. The principle of the game is the following: the player inserts coins, pulls the handle and then checks the combination of symbols on the lines. The main objective is to match certain symbols on the paylines. But the player can do nothing to affect this. Slot machines can be found in many denominations from 5 cents to being the most popular, although there are also machines that accept 0 tokens.
Especially beginners like slots. They don't have to worry about rules and regulations, or being laughed at by the other players for making a bad play, all they have to do is try to hit the jackpot by matching the highest paying symbols on one of the pay lines.

Slot machines are honest because state gaming commissions make sure they are. But there are some manufactures that design the slots in such a way that they can deceive players.
In the old days, slot machines worked mechanically, with independent wheels spinning until they each stopped randomly. Modern slot machines differ form the old ones greatly. Now the integral part of any slot machine is a chip, which is programmed to select numbers randomly. The numbers the computer selects correspond to the symbols that appear on the slot machine’s screen. There is a computer code. It generates the random numbers and determines whether the slot machine is loose or tight. The gaming inspector will examine the machine to make sure it will not deceive the player. The machine has to pay out either to the legal rate or better. Of course the latter happens very seldom.
It is next to impossible to say whether the chip is programmed not in a right way because the machine is not supposed to pay out with every spin. The machines have to be examined before people begin to play them. Of course it is very difficult to examine every single machine, that’s why inspectors examine only brands. If inspectors approve the brand, they can produce machines, and change them. But these changes must cover legal requirements. Some dishonest manufactures use the right to produce machines, but use a different chip, which is programmed to pay less or not so often.
There is an example when there was inserted an illegal tip which doesn’t allow royal flushes. Or a chip that shows near misses of a jackpot. One the one hand the machine would never have a jackpot and the player would keep on playing. Don’t keep silent if you come across such slot machine. Inspectors will respond by pulling the slot machine’s chip and seeing if it is an approved chip. Manufacturers that cheat are fined or they can lose their license.

Meet the man who beat the 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.
Carmichael, now 53, had a long history of inventing devices to cheat slot machines. He was caught with one, called a top-bottom joint, and sentenced to prison. Upon his release, he continued to work on the problem and to devise a better way to cheat the new slot machines. For example, he invented a tool called a slider made from guitar wire that he used to insert into the machine and trip a switch, which released coins from the hopper.
Later, as slot machines became computer based, he had to invent a new tool. He fooled a manufacturer into believing he was a customer and showing 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. 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.
Eventually, all good things come to an end. For Carmichael, they ended in front of a slot machine at Circus, where he was caught with the light wand when he tried to run from security. While charges from that incident were later dropped, he was caught under similar circumstances in Laughlin and later Atlantic City. By this time, authorities had tapped his phone and recorded conversations with other cheats who used his device. He served three years’ probation and lost both homes. He has been banned from entering any casino.