History of Slot Machines

Charles Fey

Long before the online slots that are known today, the original slot machine was created in the 1890’s when it was invented by German immigrant Charles Fey, a mechanic living in San Francisco. He called the slot machine the Liberty Bell, and it consisted of 3 reels with 10 symbols on each. The symbols were based on poker, and consisted of the court and suit cards (jack, queen and king, as well as hearts, spades, clubs and diamonds).

The original method of playing a slot machine was simple. The player would insert a penny, nickel or dime (hoppers that accommodated quarters came later) and the machine would payout if three matching symbols aligned. Three liberty bells resulted in a jackpot.

Prohibition of Slot Machines

A few short years after its invention, the slot machine was almost lost forever. Prohibition made gambling illegal, meaning that the slot machines, unlike playing cards and dice which had other uses, would have no market.

The owners of the slot machines became creative, changing its original symbols, which most people knew to be associated with gambling (poker in particular), to a more innocent series of symbols consisting of fruit, still commonly used today, and gum, which eventually evolved into the BAR symbols currently used in modern slot games. Rather than paying out cash, the slot machines would award players with prizes of gum and candy. As a result, proprietors were able to keep their slot machines profitable and in play.

Slow Start

Casinos were slow to accept slot machines. They took up a considerable amount of space compared to regular tables, and due to their mechanical nature, paid out quite often as a result of few reel combinations. This meant less profit for the casino.

This was changed in the 1970’s, as electronic parts were added to the purely mechanical slot machines. Some notable changes were the allowance of more sizable bets, and the hoppers being increases in size to allow quarters to be bet as well.

These changes resulted in a more profitable slot machine, bringing them into favor of casinos.

Random Number Generators

One of the biggest evolutions to occur in slot machines (besides the creation of online casinos) was the invention of the random number generator, or RNG, in the 1980’s. The random number generator is computer capable of creating thousands of virtual reel combinations internally (instead of the extremely limited mechanical stops on slot machine’s reel).

A slot machine’s random number generator also allows casinos to predetermine a payout percentage to be used by the machine. With this, the slot machine can run forever and still turn a profit over time as payouts occur at a fixed rate.

The creation of the random number generator made the slot machine’s arm unnecessary, as a ‘spin’ button that activated the game became available. Slot machines still use the handle, as some players prefer to use it, and it had become characteristic of the machine.


Coming a far way from their humble beginnings, slot machines have gained acceptance in casinos, now accounting for over 75% of most casinos’ revenue, as well as floor space.