Random Number Generator
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. A Random Number Generator determines the positions of the reels. It is included into the machine's software.
The RNG is constantly generating random numbers at an extremely high rate. The most recent random number is used to determine the result when the Play button is pressed. This means that 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 RNG was noticed to generate not exactly random numbers. It turned out that The number sequence is repeated time after time. The cause of it is in poor programming. To build pseudo RNGs with very long periods is relatively easy. No computer can complete a single period in the expected lifetime of the universe. Ronald Dale Harris, a former slot machine programmer, was the only one who had access to the pseudo RNG code and seed values. Specific gambling games equations 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 player cannot tell where in the sequence they are.

Percentage Of The Payout
Slot machines are typically programmed to pay out as winnings 82–98 per cent of the money that is wagered by players. This payout percentage is called theoretical. The minimum theoretical payout percentage is controlled by jurisdictions. It is typically established by law or regulation. 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. As for the rest of the money it goes to the players.
A slot machine's theoretical payout percentage is set at the factory when the software is written. Physical swap of the software is needed for changing the payout percentage after a slot machine has been placed on the gaming floor. As it is a time-consuming process it is done infrequently. One can find a tamper-evident seal on the EPROM in certain jurisdictions. 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. 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.

Machines Linking
Linking the machines in a special way is made 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. The amount of the progressive jackpot is far higher than any single slot machine's.
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
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.
Such showing combinations that are similar to winning combinations more frequently than would occur randomly is called near-miss programming.
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. This phenomenon only occurs where abbreviated physical reels are used to display a win pattern based upon the RNG. In video slot machines the symbols that appear around the winning line are usually an accurate depiction of how the reels were mathematically modeled.
The Nevada Gaming Commission investigated the issue of a near-miss above or below the pay line. So long as the near-miss above or below the pay line was not specially programmed it was recognized legal. In other words, the near-miss must be just as likely to occur as 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. 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.
Modern slot machines are controlled by EPROM computer chips 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. An example of modern ways of slot machine defrauding is directing microwaves toward it to disrupt its proper functioning.

Here is the list of the most amusing myths concerning slots.
You can spot a winning slot machine.
The only way one can say that theslot machine is a winning one is only to catch this moment, when the machine pays out. 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.
If this were true, it would be the only machines anyone would play. A casino mixes slots all over the casino floor. No one with any experience at playing slots would make a statement like this.
Count the number of symbols on the reels to determine your odds.
It is a rude mistake. RNG decides when the machine will stop and there are thousands of combination available on a 3 reel slot machine.
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.
It is not so. With every game the chances of winning are the same.
Pulling the slot machine handle produces more wins than pressing the spin button and visa versa.
It is also a mistake. These things are only mechanisms for beginning the game. The machine knows whether you win or lose before the symbols begin to stop.
Playing with hot coins improves your chances.
Once again, the computer determines a win or loss and the temperature of the machine or moneyirrelevant. Although it's funny that people still burn their fingers with lighters believing this works.
Casinos set slot machines to payback more on the weekends.
One more rude mistake. The chances and odds are always the same. It doesn’t matter when you play.

Slot machines have a vivid and diverse history. They came through a number of changes and improvement. But the objective and the principle of the game always remain the same. The player inserts coins in the machine and then wins or loses according to the outcome of the game.
Basically, slot machines are all the same. They only differ in some peculiarities: odds, payouts, payout percentage and symbols. 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. In single line slots, the machine has just one line of reels, usually with 4 or 5 wheels, while in multiline there are a number of reel 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. Sometimes you don't win anything at all, and sometimes multiple combinations award you with relatively big winning money. There are machines with paylines; that is, vertical lines along which a winning combination must occur, but some don’t have them, as the winning combination may come in diagonals, zigzags, strange curves and in other ways and fashions.
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. The new invention is a slot machine online, which doesn’t differ greatly from regular slot machines. 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.

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.
When the first slots only appeared cheating was impossible because they worked mechanically, with independent wheels spinning and then stopping 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. After selecting a number a corresponding symbol appear on the 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. Before the machines are installed in casinos they are examined by inspectors. But you must understand that inspectors can’t examine every machine. They examine the brands. Once inspectors approve a brand of machine, the manufacturers can make changes to individual machines as long as the changes fall within the legal bounds. Manufacturers can change chips to make a machine pay less as long as the inspectors have approved that particular chip.
For example, the Nevada Gaming Commission caught American Coin using chips that did not allow poker royal flushes. Or a chip that shows near misses of a jackpot. The player would never hit a jackpot but keep on playing maximum bets. If you think that you have come across such a machine you have a right to complain. 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.

Have you ever met a man who has 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. He was caught with one, called a top-bottom joint, and sentenced to prison. After the release Tommy began to invent new kinds of devices for cheating slot machines. 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. He fooled a manufacturer into believing he was a customer and showing him the inside 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. With all this money he bought expensive cars, houses and what not.
Eventually, all good things come to an end. 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.