Terminology Bonus is a special feature of the particular game theme, which is activated when certain symbols appear in a winning combination. In the bonus, the player is presented with several items on a screen from which to choose. As the player chooses items, a number of credits is revealed and awarded. Some bonuses use a mechanical device, such as a spinning wheel, that works in conjunction with the bonus to display the amount won.
Candle is a light on top of the slot machine. It flashes to alert the operator that change is needed, hand pay is requested or a potential problem with the machine.
Carousel refers to a grouping of slot machines, usually in a circle or oval formation.
Coin hopper is a container where the coins that are immediately available for payouts are held. The hopper is a mechanical device that rotates coins into the coin tray when a player collects credits/coins (by pressing a “Cash Out” button). When a certain preset coin capacity is reached, a coin diverter automatically redirects, or “drops”, excess coin into a “drop bucket” or “drop box”.
Credit meter is a visual LED display of the amount of money or credits on the machine.
Drop bucket or drop box is a container located in a slot machine’s base where excess coins are diverted from the hopper. Typically, a drop bucket is used for low denomination slot machines and a drop box is used for high denomination slot machines. A drop box contains a hinged lid with one or more locks whereas a drop bucket does not contain a lid. The contents of drop buckets and drop boxes are collected and counted by the casino on a scheduled basis.
EGM is used as a short-hand for “Electronic Gaming Machine”.
Hand pay refers to a payout made by a slot attendant or cage, rather than the slot machine. A hand pay occurs when the amount of the payout exceeds the maximum amount that was preset by the slot machine’s operator. Usually, the maximum amount is set at the level where the operator must begin to deduct taxes. A hand pay could also be necessary as a result of a short pay.
Hopper fill slip is a document used to record the replenishments of the coin in the coin hopper after it becomes depleted as a result of making payouts to players. The slip indicates the amount of coin placed into the hoppers, as well as the signatures of the employees involved in the transaction, the slot machine number and the location and the date.
Low Level or Slant Top slot machines include a stool so you can sit and play. Stand Up or Upright slot machines are played while standing.
Optimal play is a payback percentage based on a gambler using the optimal strategy in a skill-based slot machine game.
Payline is a straight or zig-zagged line that crosses through one symbol on each reel, along which a winning combination is evaluated. Classic spinning reel machines usually have up to nine paylines, while video slot machines may have as many as one hundred.
Rollup is the process of dramatizing a win by playing sounds while the meters count up to the amount that has been won.
Short pay refers to a partial payout made by a slot machine, which is less than the amount due to the player. This occurs if the coin hopper has been depleted as a result of making earlier payouts to players. The remaining amount due to the player is either paid as a hand pay or an attendant will come and re-fill the machine.
Display screen of a slot machine in tilt mode
Display screen of a slot machine in tilt mode
Tilt In the old mechanical days, slot machines had tilt switches. While modern machines no longer have tilt switches, any kind of mechanical failure (door switch in the wrong state, reel motor failure, etc) is still called a “tilt”.
Theoretical Hold Worksheet is a document provided by the manufacturer for all slot machines, which indicates the theoretical percentage that the slot machine should hold based on adequate levels of coin-in. The worksheet also indicates the reel strip settings, number of coins that may be played, the payout schedule, the number of reels and other information descriptive of the particular type of slot machine.
Weight count is an American term, referring to the dollar amount of coins or tokens removed from a slot machine’s drop bucket or drop box and counted by the casino’s hard count team through the use of a weigh scale.
Pay table
Each machine has a table that lists the number of credits the player will receive if the symbols listed on the pay table line up on the pay line of the machine. Some symbols are wild and will pay if they are visible in any position, even if they are not on the pay line. Especially on older machines, the pay table is listed on the face of the machine, usually above and below the area containing the wheels. Most video machines display the pay table when the player presses a “pay table” button or touches “pay table” on the screen; some have the pay table listed on the cabinet as well.
Technology
Random number generator
It is a common belief that the odds on a machine have something to do with the number of each kind of symbol on each reel, but in modern slot machines this is no longer the case. Modern slot machines are computerized, so that 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 the reels will come to rest on are chosen by a Random Number Generator (RNG) contained in the machine’s software.
The RNG is constantly generating random numbers, at a rate of hundreds or maybe thousands per second. As soon as the lever is pulled or the “Play” button is pressed, the most recent random number is used to determine the result. 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.
Some professional gamblers observe that the RNG does not actually generate random numbers. Indeed, most RNGs (so-called pseudorandom number generators or PRNGs) will eventually repeat their number sequence. This behavior is due to poor programming, as it is relatively easy to build PRNGs with periods so long no computer could complete a single period in the expected lifetime of the universe. Having access to the PRNG code and seed values Ronald Dale Harris, a former slot machine programmer, discovered equations for specific gambling games like Keno that allowed them to predict what the next set of selected numbers would be based on the previous games played.
Payout percentage
Slot machines are typically programmed to pay out as winnings between 82 to 98 percent of the money that is wagered by players. This is known as the “theoretical payout percentage”. The minimum theoretical payout percentage varies among jurisdictions and is typically established by law or regulation. For example, the minimum payout percentage in Nevada is 75 percent and in New Jersey is 78 percent. The winning patterns on slot machines, the amounts they pay, and the frequency at which they appear are carefully selected to yield a certain percentage of the cost of play to the “house” (the operator of the slot machine), while returning the rest to the player during play. Suppose that a certain slot machine costs $1 per spin. It can be calculated that over a sufficiently long period, such as 1,000,000 spins, that the machine will return an average of $950,000 to its players, who have inserted $1,000,000 during that time. In this (simplified) example, the slot machine is said to pay out 95%. The operator keeps the remaining $50,000. Within some EGM-development organizations this concept is referred to simply as “par”. “Par” also manifests itself to gamblers as promotional techniques: “Our ‘Loose Slots’ have a 93% Pay-back! Play now!” As an aside, the “Loose Slots” actually may describe an anonymous machine in a particular bank of EGMS.
A slot machine’s theoretical payout percentage is set at the factory when the software is written. Changing the payout percentages after a slot machine has been placed on the gaming floor requires a physical swap of the software, which is usually stored on an EPROM but may be downloaded to Non-Volatile Random Access Memory (NVRAM) or even stored on CD-ROM or DVD depending on the technological capabilities of the machine and the regulations of the jurisdiction. Based on current technology, this is a time consuming process and as such is done infrequently. In certain jurisdictions, such as New Jersey, the EPROM is sealed with a tamper-evident seal and can only be changed in the presence of Gaming Control Board officials. Other jurisdictions, including Nevada, randomly audit slot machines to ensure that they contain only approved software.
In many markets where central monitoring and control systems are used to link machines for auditing and security purposes, usually in wide area networks of multiple venues and thousands of machines, player return must usually be changed from a central computer rather than at each individual machine. A range of percentages are preprogrammed into the game software and selected by configuring the machine remotely.
In 2006, the Nevada Gaming Commission began working with Las Vegas casinos on technology that would allow the casino’s slot manager to change the game, the odds, and the payouts remotely via a computer. The change cannot be done instantaneously, but only after the selected machine has been idle for at least four minutes. After the change is made, 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.
Linked machines
Often machines are linked together in a way that allows a group of machines to offer a particularly large prize, or “jackpot”. Each slot machine in the group contributes a small amount to this progressive jackpot, which is awarded to a player who gets (for example) a royal flush on a video poker machine, or a specific combination of symbols on a regular or 9 line slot machine. 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 machines may be owned by the machine maker who is responsible for paying the jackpot. The casinos lease the machines rather than owning them outright. Megabucks may be the best known example of this type of machine. Megabucks Nevada starts at $10,000,000 after a jackpot. (Prior to September 2005, Megabucks Nevada reset to $7,000,000.) The new penny Megabucks video game also has a jackpot that starts at $10,000,000.
Slot machines that are not linked to a large regional jackpot such as Megabucks usually have higher payout percentages, as linked machines have to take into consideration the large jackpot amount into their payout percentage calculations.
Near-miss programming
Because the reel display of modern slot machines is controlled by computer software, it is possible to make the slot machine frequently display combinations that are close to winning combinations. For instance, if the jackpot combination is “7-7-7″, a slot machine could be programmed to frequently display “7-7-(non-7)”. This can fool the player into thinking they “almost won”, teasing them into playing more often.
This practice of showing combinations that are similar to winning combinations more frequently than would occur randomly is called “near-miss” programming. It has been ruled illegal in the U.S. states of Nevada and New Jersey. The Nevada Gaming Commission did review some machines with this type of programming and refused to authorize them.
There is a related phenomenon that is also sometimes called “near-miss”. The chance of a winning combination appearing on a payline is controlled by the winning percentages programmed into the slot machine. However, the combinations appearing 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 payline than on the payline. Using the same example above, it is much more likely that a “winning combination” of “7-7-7″ would appear on a line above or below the payline than the chance that it would appear on the payline. This phenomenon only occurs where 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 payline was also investigated by the Nevada Gaming Commission. They ruled that this was legal, so long as the “near-miss” above or below the payline was not specially programmed. 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 payline.
The calculation is more complicated than implied here. The stops are not ‘programmed’ in the sense that their outcome is the result of a calculation. In fact, the reel strips (like a mechanical poker machine) are designed so that the machine will pay according to the relevant RTP.
Near-miss programming, where a near miss is inaccurately displayed (i.e. the player is shown something that is not an accurate representation of the reelstrips) is not allowed in Australia either. Due to this, regulators use stop motion cameras to audit manufacturer’s practices.
Fraud
Mechanical slot machines and their coin acceptors were sometimes susceptible to cheating devices and other scams. One historical example involved spinning a coin with a short length of plastic wire. The weight and size of the coin would be accepted by the machine and credits would be granted. However, the spin created by the plastic wire would cause the coin to exit through the reject chute into the payout tray. This particular scam has become obsolete due to improvements in newer slot machines.
Modern slot machines are controlled by EPROM computer chips and, in large casinos, 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. Early computerized slot machines were sometimes defrauded through the use of cheating devices, such as the “slider” or “monkey paw” used by notorious slot cheat Tommy Glenn Carmichael. However, more recent attempts at defrauding slot machines involve manipulating the EPROM, such as by directing microwaves toward it to disrupt its proper functioning.Casino insiders such as Ronald Dale Harris have also been discovered manipulating the software in slot machines in order to defraud casino operators.
Regional variations
Row of slot machines inside Las Vegas airport.
Row of slot machines inside Las Vegas airport.
United States
In the United States, the public and private availability of slot machines is highly regulated by state governments. Many states have established gaming control boards to regulate the possession and use of slot machines. Nevada is the only state that has no significant restrictions against slot machines both for public and private use. In New Jersey, slot machines are only allowed in hotel-casinos operated in Atlantic City. Several states (Illinois, Indiana, Iowa, and Missouri) allow slot machines (as well as any casino-style gambling) only on licensed riverboats or permanently anchored barges. Since Hurricane Katrina, Mississippi has removed the requirement that casinos on the Gulf Coast operate on barges and now allows them on land along the shoreline. Delaware allows slot machines at three horse tracks, they are regulated by the state lottery commission. For a list of state by state regulations on private slot machine ownership, see U.S. state slot machine ownership regulations.
Native American casinos
Native American casinos located in reservations are not permitted to have slot machines unless the tribe first reaches a pact with the state in which it is located (per Indian Gaming Regulatory Act). Typically, a pact entitles the state to receive a percentage of the gross revenue from slot machines.
Slot machine classes
The Following statements are generalities, not actual laws for every state. There is no federal law governing slot machines, so these classifications may vary from state to state.
Some states have restrictions on the type (called “class”) 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 and a player’s chance of winning any payout is the same with every play. Class III slots are most often seen in Nevada or Atlantic City and are sometimes referred to as “Vegas-style slots”.
“Class II” slot machines (also known as “Video Lottery Terminals” or “VLTs”) are connected to a centralized computer system that determines the outcome of each wager. In this way, Class II slot machines mimic scratch-off lottery tickets in that each machine has an equal chance of winning a series of limited prizes. Either class of slot machines may or may not have a player skill element.
In general a game must have all characteristics of a Class II game to be a Class II game. Any characteristic of a Class III game makes it a Class III game. The casino pays a fee to the state for each Class III game and can only purchase so many Class III licenses. There is no such restriction for Class II games. Class II games are not so nearly regulated by the state.
Class II game characteristics
1. The player is playing against other players and competing for a common prize.
2. There is certain to be a winner in each game. The game continues until there is a winner.
3. In a given set there are a certain number of wins and loses. Once a certain combination has happened it cannot happen again until a new batch is initiated. This is most obvious in scratch card games that come in a pack. Once a card has been pulled those winning combinations cannot occur again until a new pack of cards is installed. One game is dependent on previous games.
4. The player must be an active participant. They must recognize events as they occur and must recognize when they have won and announce their winning. Bingo is an excellent example here.
5. All players play from the same set of numbers as they are announced.
Class III game characteristics
1. The player is playing against the house.
2. There is a very real possibility that the player may lose the game.
3. Each game is independent of previous games. Any possible outcome can occur in any game.
4. Wins are announced automatically.
