There was a time when the size of a jackpot was limited to the combinations formed by the number of reels and the numbers symbols on each of the reels. In 1897 Charles Fey invented the first mechanical slot machine.

His slot machine had three reels and each reel had ten symbols on it. The symbols were horseshoes, spades, diamond, hearts and bells. Lining up three bells was the top prize giving the player the jackpot. This machine would come to be known as a bell machine. Since the machine had three reels with ten symbols on each there were 1,000 combinations that could be made. 10x10x10= 1,000. The total payout for all winning combinations was 750 coins. This gave the "House" a 25 percent profit.

It is interesting to note that the pay table listed Drinks as the prizes, when in reality the machine actually paid out coins.

As slots evolved they added to the number of symbols on each reel and 20 became a standard giving a three reel machine 8,000 possible combinations. (20x20x20). By 1970 the number was increased to 22 which became about the maximum number that could be physically put on a reel. The maximum combination was 10,648 which was still not a lot for a big jackpot if the machine was to offer smaller wins. The slot makers had the choice of adding more reels or finding a way to put more symbols on each reel. Slot makers tried adding a fourth and fifth reel but these machines never really caught on with the players. That left finding a way for more symbols on each reel.

n 1984 Inge Telnaes received a patent for a device titled, "Electronic Gaming Device Utilizing a Random Number Generator for Selecting the Reel Stop Positions." International Gaming Technology IGT bought the Telnaes patent and now all slot manufacturers using what has come to be known as Talneas mapping or reel mapping must license the patent from IGT. This device allowed for the creation of what we call the virtual reel.

While a physical reel may have 22 symbols of stops on it a virtual reel can have 32 up to 256 or even virtual stops. The virtual stops are assigned to one of the symbols on the physical reel. Here are the possible outcomes for different numbers of virtual stops.

Stops                                            Outcomes

32                                                 32,768

63                                                262,144

256                                         16,777,216

512                                       134,217,218

Since you don’t know the number of virtual stops a machine has it is impossible to determine what the odds are for hitting the jackpot.

The number of each symbol on the reel can also affect the return.

Look at this example for a machine that has 32 stops on each reel. The total combinations are 32,768. Listed below is the payouts and number of occurances out of 32,768

Pay table is:

Symbol                             Pays            Occurrences                           $Payout

3 Sevens                          250                       30                                       7,500

3 Bars                                 75                        80                                       6,000

3 Cherries                          12                       12                                            144

Any 2 cherries                      8                     476                                         3,808

Any Cherry                            2                   6180                                       12,360

Total wins                             $29,812

Total bets                              $32,768

Return                                    90.979%

Here are the symbols on each reel.

Symbols                     Reel 1     Reel 2     Reel 3

3 Sevens                      5             2                3

3 Bars                           5             4                4

Cherries                       2             3                2

Blanks                         20          20               23

Now if you were to change the number of bars on reel 3 from 4 to 5 the return would increase to 95.577%.

If you decrease the number to 2 the payback would be reduced to 81.824%

If you changed the cherries on the first reel from 2 to 3 the payback would increase to 99.072

This example shows you how adjusting the symbols can affect the return of the machine.

The new video slots have video reels and many of them also incorporate bonus rounds into the game. With this technology and design, they do not have to use reel mapping as they are not confined to having only 32 physical stops on each reel. The game designers and incorporate any number of video symbols on each reel. Most of the new games have five reels but can pay numerous pay lines. The player decides how many lines they want to play and how many coins to bet on each line. The new technology used in Big Top Circus even lets the players pick symbols rather than lines. The new video reels have between 30 and 90 symbols on each reel. A machine with 50 symbols on each of the five reels would produce more than 312 million combinations. (50x50x50x50x50 =312,500,000) This is the reason the video slots can offer such large Jackpots.

Now you know the reel story behind the slot machines and how your chances of winning are related to the symbols and reels.