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Walk into any Las Vegas casino to see that slot machines outnumber table games more than 30-1. That’s because, in both brick-and-mortar and online casinos, slot games are a recreational player’s most preferred form of gambling. So, it’s no wonder that over the years developers have answered increasing consumer demand with hundreds of slot variations, starting with the early classic fruit and bells to the state-of-the art award-winning games with HD graphics and interactive features you find at Bitcoin Casino. This wonderful world of three-wheel one-armed bandits was brought to us courtesy a man named Charles August Fey during the mid-1800s. While Fey wasn’t the first to invent the slot machine, he certainly made the most significant contributions to America’s gaming industry development. Over the course of a very successful career, Fey ran into stiff competition due to San Francisco refusing to grant him a patent, but he'll forever be remembered as the “Thomas Edison of slots.” Read on to learn more about casino slots, their fascinating history, and how these creative games have evolved to become one of the greatest forms of recreational entertainment.


In 1891, Sittman and Pitt of Brooklyn, New York developed the first model slot machine. It contained five drums holding a total of 50 card faces and was based on the game of poker. Players inserted a nickel and pulled a lever hoping for a good poker hand. The drums would spin with the cards they held. There was no direct mechanism for payouts, so a pair of kings may have awarded the player a free beer, whereas a royal flush might have paid in cigars or drinks. Prizes were wholly dependent on what the local establishment had to offer. This machine proved so popular that most bars in the city employed at least one. Three years later, Charles August Fey built his first slot machine that kickstarted another form of gaming.


Charles August Fey was born in Vöhringen, Bavaria in 1862. At 15, he left home and moved to France, then to England, working five years in the nautical instrument department of a British shipyard as an apprentice. Presumably, Fey’s long stay in London allowed him to hone machinist skills, master the English language, and save enough money to travel to America. In 1885 at the age of 23, he immigrated to the United States, living at first with his uncle’s family in Hoboken, New Jersey until setting out for the “new land of opportunity.” Trekking across the U.S., he arrived later that year in San Francisco - a wide open town of saloons, honky-tonks, gambling, and the nation’s epicenter of the coin machine industry.

It was there he met Marie Christine Volkmar, but their courtship was interrupted by illness when Fey was diagnosed with tuberculosis. Told that he only had a year to live, he bought a horse and moved to Mexico. At the time it was believed that the warmer climate would assist those suffering from the disease to overcome it. While there, his health did not improve, so Fey returned to San Francisco to undergo creosote treatments. Following a clean bill of health, Fey found permanent employment as an instrument maker with California Electric Works. It was there he met two other German immigrants, Theodor Holtz and Gustav Friedrich Wilhelm Schultz, who shared Fey’s enthusiasm for mechanical devices and, particularly, slot machines. Fey also renewed his courtship with Emilie and in 1889 the two married. They had four children. It was around that time that Fey changed his name from August to Charles, supposedly because he disliked the nickname "Gus".

Fey built his first slot machine in 1894. It was then he decided to quit his job at California Electric Works and, together with Holtz, start Holtz and Fey Electric Works in San Francisco. The company was located near the first recorded slot machine workshop owned by Schultze, and it was Schultze who actually invented the first slot machine with an automatic payout mechanism called the “Horseshoe.” Schultze was awarded the first U.S. patent ever issued for a gambling machine, inspiring Fey to build a similar model. In 1895, in the basement of his Berkeley private residence, Fey completed a modified version of the Horseshoe called the “4-11-44.” The name referenced a popular lottery game called “Policy” in which 4-11-44 was the rare winning sequence. This machine paid out coins, not trade checks or tokens, making it more appealing and lucrative than traditional poker machines of the time. It became so successful at a local saloon that Fey quickly set out to produce more.

In 1896, Fey began working on his Draw Poker, a cash-paying poker machine. Meanwhile, his slot machine business flourished. So, he made the leap and sold his share of Holtz and Fey Electric Works to establish Charles Fey & Company. This is where he created many famous machines of his day, including Draw Poker, the Liberty Bell, Klondike, and Three Spindels. Today, only a historical landmark sets at the location of Fey's factory destroyed by the San Francisco earthquake and fires of 1906.

In 1898, Fey designed the Card Bell slot machine, a three-reel staggered-stop machine with automatic payout. The spinning reels activated by a lever featured suit marks that lined up to form poker hands when the reels were at rest. The machine was groundbreaking for two reasons; the lever would later be referred to as the “one-armed bandit” and players were introduced to the crucial gaming machine elements of drama and suspense. The Card Bell design eventually evolved into the famous “Liberty Bell” - the slot machine that still forms the basis of slots today.

The “Liberty Bell,” introduced in 1897, was a modified version of the three-reel Horseshoe. Three spinning reels displaying five symbols – horseshoes, diamonds, spades, hearts, and a cracked Liberty Bell - paid .50 cents in real coins when all three bells aligned. The Liberty Bell was a huge success, so much so that it was copied by many slot machine manufacturers and spawned a thriving mechanical gaming device industry. In 1907, manufacturer Herbert Mills from Chicago produced a slot machine called the Operator Bell. By 1908 lots of "bell" machines were installed in most cigar stores, saloons, bowling alleys, brothels and barber shops. Early machines, including an 1899 "Liberty Bell,” are now part of the Reno, Nevada State Museum's Fey Collection - now owned by his descendants. Though Fey installed and managed his machines in saloons throughout San Francisco, gambling was still illegal in California, preventing him from patenting his device. This unfortunately, for Fey and California, enabled his competitors to cinch the market. Despite this, Fey’s success lay in his ability to continually refine his machines in order to capitalize on gaming industry opportunities afforded during the late 1890s San Francisco. It became the nexus between technological innovation and the rise of the modern entertainment industry.


• Today’s popular cherry and melon symbols derive from early machines, like the “Trade Stimulator,” with pictures of fruit-flavored symbols on the reels that paid winnings in the form of chewing gum.

• The BAR symbol, now common in slot machines, was derived from an early logo of the Bell-Fruit Gum Company.

• Food, beverage, and cigar prizes were a commonly used winning payout technique to avoid laws against gambling.

• In 1963, Bally developed the first fully electro-mechanical slot machine called “Money Honey, a model that introduced a bottomless hopper and automatic payout of up to 500 coins without the help of an attendant.

• In 1976, Las Vegas based Fortune Coin Company developed the first true video slot machine that went on trial at the Las Vegas Hilton Hotel that used a modified 19-inch Sony Trinitron color receiver for the display and logic boards. The video slot machine was eventually approved by the Nevada State Gaming Commission and distributed along the downtown and Strip casinos.

• Fortune Coin Co. and their video slot machine technology were purchased by IGT (International Gaming Technology) in 1978.


Slot machines use a random number generator. Early slot machines were mechanical (think coin slots), but they still used a random number generator, in the same sense that a roulette wheel, a deck of cards, or a pair of dice are also random number generators. Modern slot machines use a computer to generate random numbers, and these determine the outcomes of the game.

The important thing to remember is that the results are truly random. The game doesn’t work on any kind of cyclical basis, and slot machine jackpots don’t become due. Slots don’t get hot or cold, either. They only seem to, and only then in retrospect. It’s not something you can predict any more than you can predict with any degree of certainty what the next card will be when dealing a deck of cards.

Slots usually have three to five reels. The reel is the image that spins in the front of the machine. The image on the reel is a symbol. When you line up specific symbol combinations, you win. The less likely it is to line up a particular set of symbols, the higher the payout on that particular combination. For decades, these reels were literally large metal hoops, but now that slot machines are powered by computers, they’re more often images on a video screen. Even in the case of slot machines with actual reels, the outcome is determined by the random number generator inside the computer.


Every slot game 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. This is your return on play, depending on whether you make a minimum or max bet. Some symbols are wild and can represent many, or all, of the other symbols to complete a winning 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.


Reels can stop on a symbol or on a blank space between those symbols. On early slot machine games, each symbol would have an equal chance of appearing when the reels settled, but since the introduction of computers, the odds can be convoluted.

Skill Stops

Skill stops allow the player to suddenly stop the reels from spinning simply by pressing the bet or play button.

Progressives (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 in the group of slot machines contributes a small amount to a progressive jackpot. The progressive jackpot 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 nine-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 manufacturer, who is responsible for paying the jackpot.


Online slots tournaments allow players from around the world to link to one another electronically and compete to accumulate the most coins to win prizes.

Payout Percentage

Slot machines are typically programmed to pay out 82% to 98% of the total revenue wagered by players. This is known as the "theoretical payout percentage" or RTP, "return to player.” The minimum theoretical payout percentage varies among jurisdictions and is typically established by law or regulation.

PAR Sheet

The table of probabilities for a specific machine is called the Probability and Accounting Report or PAR sheet. Despite the fact that they are confidential, occasionally a PAR sheet is posted on a website. They have limited value to the player, because usually a machine will have eight to twelve possible programs with varying payouts.



A special feature of the particular game theme, a bonus is activated when certain symbols appear in a winning combination. Bonuses vary depending upon the game. Some bonus rounds are a special session of free spins, often with a different set of winning combinations as the main game, and often with winning credit values increased by a specific multiplier. In other bonus rounds, 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.


A grouping of slot machines, usually in a circle or oval formation.

Coin Hopper

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 coins into a "drop bucket" or "drop box".

Credit Meter

A visual LED display of the amount of money or credits on the machine. On video reel machines this is either a simulated LED display, or represented in a different font altogether, based on the design of the game graphics.


Used as a shorthand for "Electronic Gaming Machine".

Free Spin

A term used to specify that the spin will be completed without a charge or on the same wager. Free spins may be triggered in a number of ways and each game uses a different method. Usually, landing a number of special symbols on reels is required to activate the free spins bonus round. The player keeps the profit after the spins are complete.

Optimal Play

A payback percentage based on a gambler using the optimal strategy in a skill-based slot machine game.


The 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. Paylines could be of various shapes (horizontal, vertical, oblique, triangular, trapeziodal, zigzag, etc.).


The process of dramatizing a win by playing sounds while the meters count up to the amount that has been won.

Scatter Symbols

These work differently than winning symbols and award a prize whether or not they land on a payline. Scatter symbols may also be used to award a number of free spins. Scatter symbol is a unique symbol that cannot be substituted with a wild symbol.

Wild Symbols

Like jokers that substitute for all other symbols in the game. They can appear on any of the reels. However, this is not mandatory and can be changed from game to game. In some games, wild symbols can appear only on certain reels. Or, they can appear only during the bonus rounds. The player must refer to the rules and paytable of the game to learn about the landing rules. In online slot games, they can also be used for winning a jackpot, multiplying the prize and/or triggering a certain feature.

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