Mechanics to Mathematics: Evolution of the Slot Machine

Fruit Machine

Slot machines are among the most popular gambling games in the world. Dominating most land-based casinos floors, as well as the pages of their online counterparts, they’ve been a mainstay in the industry for many, many years. Most of today’s machines are heavily computerised and use advanced random number generators that are powered by the very latest processing technology – all of a far cry from their humble 19th century origins.

In their most basic form, mechanical slot machines require a player to insert a coin. In turn, this unlocks a side-handle that, when pulled, starts a set of reels spinning. These reels are decorated with various symbols and eventually stop in sequence, often from left to right. Perforations in small plates contained within the spinning wheels and which correspond with their symbols, trigger a pay-out when theyline up in certain combinations. Although a relatively straightforward process, for 19th century inventors, devising such a mechanism required a fair amount of toil and tears.

The Mechanical Age

Things began rather tentatively during the 1870s with counter-top units known as ‘trade stimulators’. These often sat next to the cash register at a bar or shop and were designed to encourage patrons to indulge in a quick game of chance. Many of them dispensed fruit-flavoured chewing gum with pictures of the different flavours on their reels. These gave rise to the ubiquitous cherry and melon symbols that we still see today.

The Guessing Bank

The most famous trade stimulator was called the Guessing Bank which was created by New Yorker, Edward McLoughlin in 1876. A coin was inserted into the machine that would cause a dial to spin and then stop on a random number. The player guessed the number on which they thought the dial would land, making a note of their choice before inserting a coin. If correct, they won a prize.

The Playing Card Connection

In 1890, Ideal Toy Company from Chicago introduced a machine which was designed to automate the game of poker. The insertion of a coin caused five reels to spin which came to a stop when a full poker hand had been displayed. The player with the most valuable hand won a prize which could then be collected from the attendant. This is the reason why playing cards are still used to decorate slot reels.

Brooklyn-based company, Sittman and Pitt produced a slightly more sophisticated version in 1893 which comprised of five drums, of which each contained 50 card faces. Players inserted nickels and pulled a lever in the hope of landing the best poker hand. The machinesoon became popular in New York and was installed in bars around the city. Although it couldn’t pay-out money, local proprietors got around this by awarding winners with free alcohol. However, in order to preserve their cellars, many took to adjusting the machines to make the odds more favourable to the house.

Lighton’s 3 for 1

The first slot machine to offer automatic pay-outs was created by John Lighton in 1892. Named the 3 for 1, it featured a crude but rather effective design. After a coin had been inserted it travelled down one of two channels. One led to the machine’s cash box and the other was fitted with a lever. When this lever was tripped, another two coins were released in addition to the original deposit.

A year later, an inventor named Gustav Schultze combined Lighton’s 3 for 1 system with a spinning dial mechanism which he called the Automatic Check Machine. This contraption required the player to pull a side lever that caused a dial to spin and then stop on a coloured wheel. If it landed on a certain colour, a bell would sound and two coins released to the player with a token for money. Despite the check machine’s popularity, the 3 for 1 was soon rendered obsolete by another inventor called Charles Fey.

Charles Fey, Automatic Pay-Outs and the Bell Variants

Up until 1898, card machines were by far the most popular slot games, despite the lack of a pay-out mechanism. Difficulties lay in the endless winning combinations which could arise from the five drum, ten-card format being used. Although automated pay-outs were available in slot machines, they were small and infrequent due to the machines’ limited capacity for coins.

The Card Bell

Charles Fey initially tried to solve this problem by attempting to add a pay-out mechanism to a five-reel poker machine. However, when this proved too difficult, Fey set about creating a three-reel slot in order to reduce the complexity of reading a win. The new machine was completed in 1898 and was the first to offer automatic pay-outs on all winning combinations. Christened the Card Bell, the innovative slot used three reels imprinted with playing-card symbols which could be set in motion by pulling a lever. Wins were achieved by lining up winning poker hands, much like Sittman and Pitt’s machine.

The Liberty Bell

Because gamblers were no longer playing for poker hands, Fey decided to remove the card symbols replacing them with images of horseshoes, stars and bells. Renamed the Liberty Bell, the updated slot featured a ten-nickel jackpot and was the very first offer three-reel gameplay. But despite its huge popularity in Fey’s home town of San Francisco, the now famous inventor was reluctant to expand production beyond the California state line.

Instead, he opted to strike deals with local bar owners, installing his highly sought-after machine in their establishments in exchange for a 50% stake in the takings. Fey’s cautious approach eventually proved fateful when, in 1906, the San Francisco earthquake struck, destroying his factory and workshops. This led either directly or indirectly to the acquisition of the liberty bell by competitor Herbert Mills.

The Mills Liberty Bell

Various stories abound regarding just how Herbert Mills got his hands on Fey’s ground-breaking slot machine. Some say that he instructed an employee to ‘acquire’ one from a San Francisco tavern so that its inner workings could be studied and then copied. Others insist that he struck a deal with an impoverished Fey who was still reeling (pun not intended) from the Great Earthquake.

Whatever the truth, by 1907 Herbert Mills had acquired the rights to the liberty bell and wasted little time in putting the slot into mass production. After making the machine available nationwide for the first time, its popularity soared while at the same time rendering dial machines obsolete. In turn, the big manufacturers soon caught on and began to produce them on an industrial scale. This went on well into the 1960s, with very few changes made to the way in which slot machines were created for the next fifty years or so.

1960s – The Electromechanical Age

In spite of their undoubted success and extended production life, mechanical slot machines were hampered by a particular problem. Because they only used three reels, the number of possible combinations was cubic. So a slot with three reels and ten symbols on each could only return 1000 possible outcomes.

Consequently, there was very little room for additional pay-outs which resulted in rather boring, high-variance gameplay. To make matters worse, wins of more than $25 dollars had to be paid by an attendant. However, things began to change in 1963 with the introduction of the first truly electromechanical slot machine – the Money Honey.

The Money Honey

The Money Honey was developed by Bally Entertainment and used an electronically-controlled mechanism. It also featured a bottomless hopper allowing for bigger pay-outs of up to 500 coins, thus removing the need for assistance from an attendant. In addition, the Money Honey made use of buttons instead of the traditional side-lever. Unsurprisingly, it became a huge hit resulting in a major upturn in fortunes for Bally. By the mid-to-late 1960s, it had produced more than 90% of all casino slots in Las Vegas.

The end of the 60s also saw the introduction of more refined electromagnetic units such as Bally’s 809, which offered a pay-out proportional to the deposit. Many of the slots created during this time were also capable of monitoring multiple pay-lines and coin plays, with some even able to chart progressive jackpots.

The Microprocessor

By the 1970s, manufacturers had started to use solid-state circuitry in their slots resulting in the first fully-electronic units. These soon started to incorporate microprocessor componentsto help control internal system mechanisms such as the reels. By far the most important of these new advancements was the random number generator.

Essentially a small computer which simulates the spinning of reels, the RNG did away with mechanically-generated wheels and, in conjunction with pre-programmed formulas, more accurately determined the symbol combinations and pay-outs.

The new technology also allowed for a more sophisticated and predictable method for ensuring accurate RTPs. It also opened up new avenues with regards to the game interface, allowing manufacturers to use video screens to display reels. The Fortune Coin Company was this first to take advantage of this.

The Fortune Coin Video Slot

In 1975, Walt Fraley unveiled the Fortune Coin Video Slot. Featuringa modified 19-inch Sony Trinitron video screen, this Fortune Coinmade full use of random number generators and logic boards to control all of its functions.

The first units went on trial with the Las Vegas Hilton Hotel and, following a number of modifications, were approved by the Nevada State Gaming Commission. Although players were initially cautious, the machinequickly caught on and became especially popular on the Las Vegas strip. After IGT’s takeover of the Fortune Coin Company in 1980, it was improved further with the addition of multiple pay-lines.

The Video Slot Revolution

Flushed from their success with the Fortune Coin Slot, IGT began to produce more versions. It was clear that video slots held clear advantages of over mechanical reels, especially when it came to maintenance and reliability.

In addition they were almost tamper-proof and nigh on impossible to cheat. Thus began the video slot era, which continues to this day. The technology first developed by the Fortune Coin Company soon took over the industry, paving the way for advancements such as coinless machines as well as ‘second screen’ bonus games. This latter feature first appeared in 1994 with Australian slot machine ‘Three Bags Full’ and then Reel ‘Em In from WMS Industries in 1996.

The Internet Arrives

The introduction of the internet in the late 1990s opened up all manner of opportunities for manufacturers. In fact it revolutionised gambling, just as the Liberty Bell had done more than one hundred years earlier.

Although the technology was initially lacking, gradual improvements in processing power and browser functionality helped to create a platform upon which manufacturers could offer an immersive gambling experience.

Despite a degree of scepticism to begin with, the big industry player soon cottoned on to the enormous potential offered by virtual gaming. By the early to mid-2000s, most if not all major slot machine companies offered online versions of their land-based machines.

Present Day Slot Machines

Today, video and computer-powered machines are pre-eminent. Such is their dominance that they account for between 70-80% of revenue generated by most bricks and mortar casinos. For online casinos it’s even higher with total revenue closer to 80%.

Although the era of mechanical slot machines is well and truly over, traditional ‘one-arm-bandits’ are still produced, albeit in much smaller numbers. In Las Vegas particularly, casino floors are still populated by machines with fully-operational side levers in addition to the electrical buttons.

A typical hotel lobby on the strip will also reveal row upon row of mechanical slots which, despite being technologically obsolete, remain extremely popular with the hordes of gamblers who descend on the desert city each year. So it seems that the charm and unpredictability of classical slot machines remains as strong as ever, even if the industry has been taken over by the clinical precision of computerisation and random number generators. What would Charles Fey have made of it all?