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Mystery Of The Slot Machines

Players panic when slot techs tinker with their games

by John Wilson


If you want to find a group of superstitious people, look no further than your local casino, where you will be hard-pressed to find anyone more superstitious than an avid slot player. Lucky stuffed animals, good luck charms and wishes for “Lady Luck” are common in the casino. When a machine is finally on a “hot streak,” nothing bothers an avid slot player more than someone tinkering with his or her machine. Like walking under a ladder, will opening up your machine cause bad luck to follow?

Have you ever been playing your favorite slot machine only to have casino staff come up and say that they need your machine for a moment? Typically they will remove your players card, insert their employee card, then do whatever they do, usually filling the compartment with coins (where coins are still used). The ticket-in, ticket-out machines have virtually ended this type of interruption.

One burning question remains. Whenever a slot attendant touches your machine or opens the door for whatever reason, what actually occurs within the machine? Have they reset it? Will your winning streak fizzle out? Did they do this because you were winning too much and they needed to adjust the machine’s payout?

I’ve often heard people complain that their game is no longer paying out after the pesky staff “touched” their machine. There’s a common feeling that the attendant somehow tinkers around with the machine and “turns down the payout.” Is there a secret dial that adjusts the payout of the machine? Or, is this team of coin-filling staff a secret group destined to cut off your winning streak before it gets out of hand?


“Charlie Seven from dispatch. Proceed to machine 1623 in the quarters’ section. There’s a lady who just won mixed 7s. Reset her machine before she hits the jackpot.” “Roger, Blue leader.”

Apart from any conspiracy theory, we know that there are times when an attendant must perform some sort of reset on our game. Does this have any effect on your game? Will it cause your hot machine to go cold?

The best way to find answers to these questions is to actually peer inside the machine and study just what happens when this reset is performed. You can’t do this on your own and the casino staff frowns on patrons reaching inside of an open machine. Must we meet a slot technician in a darkened ally to talk about what happens? No, this seems too dramatic. Fortunately, we can take a leisurely stroll through a slot machine this month and see what we can actually do to it.

First of all, why the secrecy about the inside of the machines? Why does staff have to put in their card and touch a bunch of buttons? The answer is simple—security. Believe it or not, the casino is more concerned with the staff than they are the players. You don’t get to go inside the machine like the staff does. Why be so concerned about the inside of the machine? In those casinos still using coins or tokens, there is a hopper full of them—2,000 in the case of a quarter machine. That’s $500 that could be scooped up. Also, there’s hundreds and thousands of dollars in currency that has been put into the bill validator. In short, there’s a lot of money inside the machine. The second, and perhaps most important item, is one of accountability. Many gaming regulators require a log be maintained of each time the inside of the machine is accessed. In the case of the slot machine we’re looking at, the front door has been opened 1,568 times since it was put on the casino floor. These machines even record the door being opened when the power is off. This means that any time anyone goes inside the machine, there is a record kept.

You may have noticed that whenever the slot attendant opens the door he or she writes in a little book. This is called a MEAL card and stands for Machine Entry Access Log. This is a document that must be kept by law. Gaming commissions want to know what the casinos are doing with the machines and the casinos must provide documentation of the same.

One reason for this documentation is for patron complaints. Perhaps you decide to complain to the casino, or the governing gaming commission, that some casino staff opened your machine, flipped some switches and took away your jackpot. It can be determined who was in the machine, exactly when, and what they were doing. Videotape of the same time would also document this. The card that is put into the machine identifies the employee, and verifies that they have the authority to enter the machine. The code they type in is a password to ensure that someone hasn’t stolen their card and is trying to use it. The high-security key opens up the physical lock. Many components inside have separate locks, such as the processor board and the cash box. Apart from the machine’s own record of people inside, the casino’s computer system maintains a record of access as well and verifies the machine’s log. This multilevel process ensures that the records agree with each other and confirm the reason for access. In short, if anyone opens up the door of the slot machine for any reason there are a number of records kept of this action.

Well, that may be fine, but once inside the machine, what can you do? The “reset” button is required for security purposes. The reset doesn’t do what you think, though. It doesn’t restart the machine and clear out everything that has already happened. The term reset is not really an accurate term. A more appropriate word would be acknowledgement. Opening the door and then closing it can clear simple tilts or errors. Other more serious errors require this reset, or acknowledgement.

Suppose that you cash out your credits from the machine after a run of good luck and the hopper runs out of coins. Video machines will show a message stating “Call Attendant—Hopper Empty.” Spinning reels slots will display a message on the credit meter like “Hpr Err” or a code such as “3300” or “32.” The slot machine and the casino’s computer system record these codes. The error codes tell the slot attendant what has happened to cause this “tilt” condition. In the case of the “hopper empty” error, it informs the staff to refill the spare token supply in the base of the slot machine. Once the attendant fills the hopper and closes the door, your tokens continue to be dispensed. This is a “simple error,” which means that it’s an expected event that needs some form of attention.

Some error conditions or tilts are more serious. Years ago, slot cheats used a technique called “stringing.” A string was tied to a coin and once the machine accepted the coin, the coin was pulled up out of the machine. This would allow the same coin to be used over and over again. Modern slots track the motion of the coin so that a coin moving up out of the machine will be detected. Sensing this attempt to cheat, the machine will tilt and stop working until someone acknowledges the error. A slot attendant must open up the machine and press the reset button, in order to acknowledge the cheating attempt.

Other errors occur when the machine is not working properly and tells the staff to check the machine and repair the problem. In some cases the machine may encounter a serious problem that prevents it from completing the game. Perhaps one of the reels gets stuck and cannot move properly. The error code displayed on the machine will inform the technician about the problem and the machine will lock up to prevent you from continuing to use it. More than likely, the reels will go into a mode where they spin very slowly and continually to indicate that a problem has occurred. Once the problem has been fixed, the machine then needs to be reset. In reality, this sends a notification to the slot machine that a technician has seen the error and performed some form of diagnostics to fix the error. The reset simply acknowledges that the error was identified and corrective action taken. The slot machine then records this and the central computer receives an acknowledgement. The employee number is also recorded through the employee’s card inserted into the machine. Once the door is closed, the machine then goes into its “post error” state.

The machine will preserve its status before tilting and displaying the error code. Once the error has been corrected, it will resume from the point where it stopped. In all cases of tilts the machine records the symbols that should come up on the payline for the game that had the error. It then respins the reels to land on the same place they were supposed to land. They might do this automatically, or you might have to push the spin button. In all cases, however, the machine knows where it was supposed to end up and will try to get to the same place again. If another error comes up, it waits until the error is cleared and then tries again. Even if the machine has to be turned off so that some component can be replaced, the slot machine will retain the information about the game that was in progress so that it can continue when the power is turned back on. You don’t lose the spin that was taking place—the machine will respin giving you the exact same game outcome. Once more, this is a legal requirement of the gaming commission.

In order for that game to be approved for use in the casino you’re in, it must pass these tests. And these situations are checked to make sure that the machine acts appropriately. Otherwise, that spin might have resulted in a jackpot and after the error you would get a different result. Conversely, the game might have been a losing game and after the error it picked a jackpot. The gaming test labs and gaming commissions make sure that the machine works fairly. Fair applies to both the player and the casino.

Pull-Tab Theory of Slot Machines
I have a published theory on slot machines called the Pull-Tab Theory of Slot Machines. Basically, it’s a comparison of a slot machine game to the lowly pull-tab tickets, sometimes called Nevada Tickets. With these tickets, usually around 50 cents to one dollar each, there are five perforated sections that you peel open to see if you won. There are various themes, including slot machines.

Many people think that slot machines play like the pull-tab games. With the pull-tabs, the seller opens up a bag or box of tickets and puts them into a Lucite container. In the box is every possible combination of game outcome. There’s the top jackpot award of $100, the $50 second prize, a handful of $20 tickets and all of the non-winning tickets as well. Suppose that we have 400 tickets in the box and that there is only one jackpot prize. If you are the first customer, your chances are one in 400 of hitting the jackpot. After purchasing a ticket (let’s assume that you don’t win anything), your chances of hitting the jackpot have increased. You now have 1 in 399 as one losing ticket has been removed from the box. If half of the tickets are sold but the jackpot still hasn’t been won, your chances are one in 200. This is twice the chance of hitting the jackpot as the first game you played. And, if there are only two tickets left and the jackpot still hasn’t been won, it’s 50-50. One ticket is going to win $100 and the other one won’t. In this case, you’re best decision is to buy them both. A $2 wager is guaranteed to win you the $100 jackpot!

The key difference here is that in a pull-tab game winning and losing combinations are removed from the box and your chances of winning or losing changes after each game. If the first person wins the jackpot amount, then 399 people will have no chance of winning the jackpot. It’s already gone and no matter what you do, you can’t win it. With a slot machine, however, it’s not removed. If you win the super megamoney billion-dollar jackpot then you have beat great odds in winning that jackpot. However, the next spin gives you the exact same odds of winning as you had the game before. Winning and losing games are not taken away or replaced. The slot machine does not keep track of the game before so that it affects the next game. A legal requirement of slot machines in all gaming jurisdictions is that each spin of the game must have precisely the same probability of winning or losing and that the probability of each particular type of payout (three BARS, for example) will remain constant.

I believe this perception of the slot machines comes from a misunderstanding of the slot machines’ random number generator (RNG). As the machine picks random numbers, you might or might not have a winning combination selected from the random numbers. Resetting the machine does not reset the RNG. It doesn’t start over at the beginning of the random numbers. In fact, the machine will store the arithmetic process to determine the random number and it preserves this at all time. This means the slot machine might have generated 50-million random numbers when your hopper ran out of coins and the attendant had to reset it. However, the machines must retain the previous state of the random number generator and continue from this point. Even shutting off the machine and unplugging it will have no affect on this. The machine records all of the information in non-volatile memory so that when the power is shut off nothing changes. It simply picks up from where it left off. If the machine has picked 50 million random numbers when it is turned off, the next number generated when it is turned back on will be the 50,000,001st number. This means that any restarting of the machine or resetting will not have any affect on the game outcome. This is done for fairness.

Looking inside the machine, there is no large dial to “turn up” or “turn down” the payout. Nothing that a slot person does can affect how the machine plays or pays. The games are specifically required by law to preserve the information about each game so that if a tilt or error occurs, the machine will provide you with the same outcome that it would have prior to the tilt condition. There are literally hundreds of safeguards within the machine so that nobody tampers with anything. If your machine goes cold after the slot attendant is inside your machine, it’s just the turn of luck. You’re just as likely to get a winning streak.

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