How a modern slot machine works

Slot machines were originally designed to entertain customers who were not regular casino patrons. Unlike traditional table games (blackjack, poker, roulette), no special knowledge was required to understand how to play slot machines. Anyone could try their luck by placing a small bet and pulling the lever. This idea proved to be successful – slot machines over time became much more popular and began to bring the casino the bulk of the profit. Their technology has changed a lot since their inception. Today it is difficult to find classical mechanical devices – they have been replaced by computer-controlled machines. Despite this, the concept itself remains the same.


Principle of operation

Most of the new machines are designed to look like old mechanical models. However, they work on a completely different principle. The modern device of a slot machine is based on a central computer inside the machine, and not on the movement of the reels. The computer uses stepper motors to turn each coil and stop it at a given point. They are powered by short electrical pulses controlled by a computer, rather than the oscillating electrical current that drives a conventional electric motor in older gaming machines. Despite the fact that the computer tells the reels where to stop, the games are not programmed to pay out at any particular moment, for example, after a certain amount of money has been deposited into the machine. The random number generator at the heart of the computer ensures that the jackpot can land on any draw. Every time the slot machine is running, the random number generator produces integer values (usually between 1 and several billion) hundreds of times per second. The moment the player presses a button on the control panel to continue, the computer writes the next few numbers from the random number generator. He then sends these numbers through a special program to determine where the reels should stop on the next spin. In some models, the reels are replaced by a screen with video slots. When they first appeared, the players were very suspicious of them. With no reels, it seemed like every spin was rigged. Although the drums and levers in modern machines do not in any way affect the outcome of the game, manufacturers still add them to give players the illusion of control.

Payout system and probability of winning

The odds for a particular slot machine are embedded in the program on the machine’s computer chip. In most cases, the casino cannot change them on the machine without replacing this chip. Contrary to popular belief, the casino does not have the ability to instantly “spin up” the machine. In modern gaming models, there are several different payment schemes:

* a fixed amount of the main prize, which never changes;

* progressive jackpot amount, which increases as money arrives at the machine;

* the combined amount of the main prize, which includes funds received from all machines from one manufacturer within the city or country. The software in modern machines is designed specifically to achieve a certain percentage of payback. With regard to computerized slots, the term RTP (Return to Player) is used, which is a mathematical calculation of how much the slot will return depending on the number of reels spins. For example, when the payoff machines have 97% RTP, the average winnings will be around $ 3 for every $ 270 wagered.


In traditional slot machines, a mechanical generator was used to determine the results, while in modern slots, microcomputer chips are responsible for processing information. As a result, computer slots have become more efficient and provide a higher payout percentage to players compared to mechanical machines.