Thursday, June 18, 2009

Slot Machine Ring (RNG)

What is the Slot Machine Ring (RNG)?

The Random Number Generator or (RNG) is the brains of the modern casino slot machine.
While most players know that there is a computer chip picking the numbers, they do not fully
understand how it works and this can lead to some of the many myths and
misconceptions about a slot machine. One of the most common myths is
that a machine has a cycle that can let a player know when it is due to hit.
This is completely false and heres why. Inside the slot machine is a microprocessor
similar to the one in your home computer. Instead of running Word or Excel, it
runs a special program known as the RNG.
This generates numbers to correspond to the symbols on the reel of the slot machine
and decides the outcome of the game cycle. You might say that the RNG is
in perpetual motion. As long as there is power to the machine it is constantly
selecting random numbers every millisecond. The RNG generates
a value between 0 and 4 billion (approx number) which is then translated into
a specific set of numbers to correspond to the symbols on the reels. The outcome
of each spin is determined by the number selected by the RNG.
This number is chosen with the 1st hit of the spin button or 1st deposit of a
coin. The RNG uses a formula known as an algorithm which is a series of instructions
for generating the numbers. The scope of this is beyond most of our mathematical knowledge
but can be checked and varified for accuracy. This is done by the Casino Control Board and
other testing laboratories to make sure that the program performs as it should so the player
will not be cheated. While all of this may sound reasonable it still does not give the normal
person any basic understanding about how the RNG works.
I would like to try to explain it in a simplified manner that I think most of
us can relate to. Although this is not precisely how the RNG operates
it should give you a basic understanding of the principles of how the winning
spins are determined and how little affect the payout percentage chip installed
in a slot machine actually has. Reel type slot machines have a number of spaces
and stops on each reel that contain either a symbol or blank. These are refereed
to as the physical stops. Most of the old mechanical machines had reels that
could hold 20 symbols while the modern slots have reels with 22 physical stops.
The micro processing technology allows the newer machines to be able to accommodate
a large number of “Virtual stops”. I will try to simplify things by saying this:


Imagine that there are only 10 stops on each reel. With 10 stops there can be
1,000 different combinations. We get this number by multiplying the number of
symbols on each reel.

(10 x 10 x 10 = 1,000) The 1,000 combinations that can be attained are known as a cycle and this is the word that sometimes confuses a player into thinking that the machine has cycles of winning and losing. The odds of a three number combination being picked are one in a thousand. Theoretically if you play 1,000 spins you should see each of these number combinations once. However we all know that this is not the case. If you played a million spins you would see that the numbers would even out to be closer to the actual probability.
This is similar to flipping a coin 100 times. Although the odds are 50 -50 you
are unlikely to see 50 heads and 50 tails after 100 flips. This is similiar to
a Daily pick 3 lottery drawing. They have three glass bowls or drums each containing
ten balls numbered 0 -9. The balls are mixed up and when the top is lifted a
ball pops up the tube showing you the first number. This is repeated for the
second and third number to give you a three digit winning combination. To use
this as an example of the operation of the slot machine, we will replace the
numbers 0 -9 on the balls with slot symbols. In each bowl, we will have one ball
with the jackpot symbol on it. Two balls with a Bar, three balls with a cherry
and four balls which are blank. Imagine the RNG in the slot machine as the person
drawing the winning combination. Here is the breakdown of the number of times
out of a thousand that the winning combination made.

3 Jackpot 1 (1x1x1)

3 Bars 8 (2x2x2)

3 Cherries 27 (3x3x3)

Total Wins 37

There are 963 losing combinations consists of:

3 blanks

2 blanks and a symbol.

1 blank and two different symbols.

3 mixed symbols.

The RNG picks these combinations of numbers thousands of times each second. Now
imagine a string of blinking lights where only one bulb can be lit at a time.
The electrical current is zipping from bulb to bulb down the string. When you
push a button the current stops moving and the bulb in that position lights up.
In this example the light represents the three digit number just picked by the
RNG. If you hesitated a second before pushing the button the results would be
different. This is the same as you getting up from a machine and seeing someone
else sit down and hit the jackpot. The chances are astronomical that you would
have hit the spin button at the exact same millisecond.



All this comes down to this:
The percentage chip payout is based over the life of the machine. The expected service of any Commercial slot machine is at least 40 million game cycles. It might pay back 500% today and 10% tomorrow. It could also pay 180% for a month straight and then 2% for a year. The average will equal the percentage chip installed in the main board. This is why when you are at a casino you can dump $1000 or more in a slot machine, take a 5 minute walk to the restroom and when you return to the machine you were playing you see someone else sitting there with a smile from ear to ear because they just won a jackpot that should belong to you, after all the money thats in the machine was yours, wasn't it? The correct answer is no although it sure feels like it was.
Next we will take a look at some common Slot Machine terms and find out exactly what they mean.


PAR = Paytable and Reelstrip listing though it is widely refered to as the pay out percentage.
HFRQ = Hit Frequency.
PSR = A program summary report.
From what I have learned, there are two factors that are figured into a slot machine to eventually come up with the PAR.
One of those is the hit frequency and the other is the win frequency. They are mutually exclusive, Example: If you have a high hit frequency, you will have a low win frequency, and if you have a high win frequency, you will have a low hit frequency. Hit frequency is how often the machine actually pays something, and win frequnecy is how often a big jackpot is paid. All of this shapes how volatile the machine is. The way I understand it is you can't change those factors and not mess with the PAR, and that is part of what GLI checks with the math. If you know what you are looking for, you can actually observe it during machine play. Compare the play on a Double Red White and Blue with a Triple Red White and Blue. While the theme sounds the same, the volatility of the machines are worlds apart. You should see lots of small payouts on the double RWB and few jackpots,and the opposite on the Triple RWB.Hit frequency depends on how many of the possible combinations result in a win. If there are 262,144 possible combinations (a three reel, 64 positions per reel game). We may have, say 61,700 possible winning combinations (taken from a real game). For the example given, on the average about 23% of the games will result in a win of some kind.The hold of the game may be altered by either changing the number of winning combinations, or changing how much gets paid on a certain win. The first can be done without a change in the Pay Table. The second will reflect as a change in the pay Table.All reel games I have ever seen have many possible combinations to give a different Hold. The intention is that a different denomination for a given game be set to a given Hold. A casino can choose to have 2.5% of a dollar, or 10% of a quarter, and so on, each giving the casino about the same revenue per coin played.Hit frequency varies more according to different games than within a given game. A higher hit frequency makes a game more exciting The pay awards are usually lower, but coming more often. A lower hit frequency game usually has higher payouts, but is hit less often. Both games can have the same Hold.Hit frequency depends on how many of the possible combinations result in a win. If there are 262,144 possible combinations (a three reel, 64 positions per reel game). We may have, say 61,700 possible winning combinations (taken from a real game)" The stop positions refer to the printed symbols on the reel strip and is that of a typical amount of combinations? (64 ^3) My Experience with hands on debugging of many micoporcessors and some limited programming. It seems to me with todays video processing power it could be a huge number of positions and combinations. ( I mean the reels don't actually need to physically spin any moreto get to the outcome of the game, its more just scrolling video data. The same goes for the RNG.
To put it in layman terms, how many positions/possible combinations would a "money to burn", "winning bid", "jackpot party", etc have? Well, Generally, there are aproximately 32 positions per reel. (Ok 5 reels = a really big number.
High jackpot value = really low hit rate on the Jackpot, but lots of small wins. Most of the hardware is pretty standard microprocessor circuits with only a few bells and whistles added. De-engineering is seldom difficult if you have done it before (it sounds like you have). Dis-assembling firmware is time consuming but an excellent learning experience. You really get a good understanding of how the game works.
Most Stepper (reel) games have only 22 reel stops including the blanks. However, virtual numbers are assigned to the reel stops. which means that the reels can be weighted. As an example assign more virtual numbers to the blank spaces on a slot machine reel. (usually blank spaces around the symbols for the top award) This of course intices players to stay at a machine for longer periods. Im not totally sure but with the memory limitations on IGT S+ machines highest number of virtual reel stops is 64^3 however on video reel machines appear to have as many as 88 reel stops (no virtual stops for video since they are virtual reels) now the strange thing is that they can have more reel stops for some reels than others. eg: A game with 5 reels can have 60 stops for the 5th reel 70 for the 4th 72 for the 2nd and 3rd and 88 for the 1st this would yeild 1,916,006,400 reel combos. This is a whole lot of data to work with. Can you imagine the possibilities if you tweaked either the PAR or HFRQ by fractions of a %.?

Monday, June 15, 2009

IGT S+ Slot Machine Game Conversion

IGT S+ Slot Machine Game Change
The IGT S+ upright model slot machines use 3 separate pieces of glass. These are the Top or award glass, the middle or reel glass and the bottom or belly glass pieces. These glass pieces are shown in the photo.
When replacing your slot game kit or converting to a different game some kits will include only 2 pieces of glass while others will include all 3 pieces. It really just depends on the game theme. Begin the conversion by removing the top glass. This is done by opening the slot machines main door and carefully lifting up on the glass holder bracket or player tracking bracket that holds the glass in place. Install the new upper glass. If your new kit included the (Reel) glass proceed to remove the old one by removing the florescent lamp bulb and then removing the 3 7/32" florescent fixture screws and finally the fixture itself. Once the fixture is removed you should be able to carefully slide the reel glass out of the machine by grabbing the old reel glass on both sides and carefully wiggle it out of the lower holder and replace it with the new piece of glass. (Be sure that all of your glass decal stickers are securely attached to the new glass pieces before installing the light fixture. Next, the belly or lower glass is replaced by first locating the belly door release knob found on the main door of the machine. Just pull the knob straight out to the right and the belly door will flip down allowing you to remove the the belly glass assembly. You will need to remove the 4 7/32" nuts securing the lighting fixture and then carefully slide the old glass out of the machine. When installing the new belly glass be sure that it is facing right side up with the belly door in its closed position before you tighten up the 7/32" nuts.


Replacing the Slot Reel Strips

Lay out the new strips on a flat surface and take a comparison look at the strips different symbols. If they are all the same and all the symbols line up with each other then you do not need to be concerned with which strip goes to which reel. If however, any strips are different from each other than you will need to install them in the numerical order that specified in the PAR sheet for the game.







The Reels should be numbered in numerical order from left to Right as shown above (1, 2 and 3)
The Reel Strips should also be numbered either on the bottom of the strips or on the back side. The numbers on the reel strips will indicate which strips install into which reel assembly either (1, 2 or 3) depending on your game conversion theme. (Refer to your game theme PAR sheet for specific details) The reel strips will have small notches cut in them at the bottom of the strip. The notches must align with the notches that are molded into each reel basket.

In most cases (Not all) the reel strip showing the lowest number will be installed in the left reel assembly (#1) and the next higher # reel strip will install in the middle reel, etc. If your reel strips contain different symbols on them this rule may not apply.

Locate the notches at the bottom section of the reel strips. You must install the strips aligning these notches with the notches in the reel baskets. The easiest way to do this is to place a reel strip into the left side groove of the basket that it is to be installed into and hold the strip at a 45 degree angle to the basket with one hand and use the other hand to rotate the basket slowly until you feel it catch on the notch. Then, proceed to roll the strip around the back side of the basket and as you do tuck both sides into the grooves of the basket until you come back around to where you started. At this time you want to make sure that the end of the reel strip overlaps the other end of the strip and that they are seated together with the self adhesive sticky surface on the inside of the strip. (You may have to use clear scotch tape to secure the strip to itself. If you did this correctly, you will not be able to see the notches in the strips after you are finished and the reel should spin straight and true. numbers on the bottoms or back sides of the strips so that they are installed in the correct reel.

Slot Machine Eprom Chips

If you change your "Game" eprom you will likely loose the function of the machines bill acceptor and it will require a special set chip to re-activate it. Because of this, most game conversion kits do not require nor include a new game chip as part of the conversion.
Remove IGT S+ MPU Processor Board k round handle that looks kind of like a closet or cabinet door knob. Grab a hold of it and lift straight up to remove the main system board from the lower board (Use caution and Do not use too much force to avoid damaging the lower board) Place the board in a lighted area so you can locate your Eprom game and reel chips. (The 2 chips are clearly labeled on the board) Take Notice that there is a notch in each chip at one end and pay close attention to which direction that notch is in relation to the direction the board. (See photo below) The new chip(s) must be installed in the same direction!

Install the new IGT S+ "REEL" Eprom chip that was included with your game kit in the same direction as the old one that you just removed. This means the notch in the chip must install in the same direction. Use caution when installing the chip so that you do not fold over any of the chips pins .Go slowly and re-check all the legs as you go and again after wards. If one or more of the legs do get bent, you must straighten it before proceeding. Next, push down on the top of the chip firmly until the chip is seated all the way in its holding socket. If you were instructed to also change the "GAME" chip with your new kit now is the time to do that following the same guidelines as above. You are now ready to install the system board and bring up the machine to set the games options.

Install IGT S+ Slot Machine MPU Board

Make sure you reinstall the main board the same as it was removed. The board must align on both sides of the board holder. It also must be completely seated down against the lower board. Use care to be sure both sides are square during this procedure and Don't use excessive force when seating it down against the bottom board or you risk damaging the pins that are located on the bottom.

Initialize IGT S+ Slot Machine

After installing the main system board. Install the hopper and turn the power switch on. The machine should boot and display a code "61" in the winners paid window. - (You may see a 65, 66 or 67 in the window instead) See the below illustrations and pictures to see what you need to do for each code displayed:

Press and hold the test button until you hear a "Ding" and see a 61 - 1 code displayed

If you see a "65, 66, or 67"code after making a chip change - Power off the machine, then back on. You should then see a 61 displayed in the winner paid window.

Once you get a 61- 1 close door completely and turn the rest key one time to initialize your new slot game. This is the final step in the conversion process. Congratulations! You did it!