How Slots Work  

The modern token operated slots machine or its electronic cousins, the multigame machine or video poker, is a fairly simple, robust electronic machine. All functions of the slots machine are governed by a motherboard resident in the machine, just like the computer you are sitting at. All functions of the slots machine, including the payout percentage, are controlled by this plug-in board. This board is installed at the factory, according to specifications ordered by the customer. Every aspect of design, manufacture, installation, and maintenance of slots and electronic machines is regulated and monitored by state gaming boards. The gaming boards only allow boards to be swapped out under their supervision. In other words, the machine on the floor is the same one that passed their inspection upon design, assembly, and installation. Any subsequent alteration, by the casino, must also pass muster. Generally, Indian casinos are not regulated by these state boards.

The central processing unit (chip), and the board it is attached to, tell the machine what to do. According to the program installed at the factory, it dictates: when to spin the reels, when to stop the reels, whether to credit or debit the player from the credits already fed into the machine and how much and when to pay on a jackpot. If the player is using a slots club card, another line of communication runs to the slots club computer, detailing how much is being played, how much is lost, and how much is won. This slots club record has no affect on the outcome of the slots pull.

As stated, the slots machine functions according to the set of instructions issued by the motherboard. Contained on this motherboard is a random number generator (RNG). This program is installed at the factory and determines when jackpots occur according to the payout percentage on that particular machine that was installed at the factory. For example, a machine programmed to return 85% will return very close to $85,000 for every $100,000 bet. Casinos expect machines to return their theoretical payback only over a very large (hundreds of thousands) number of pulls. The function of the RNG is to "seed" the program with a "random" pull when you push the "play" button. This is a game of chance, after all, and the RNG assures all concerned that it remains so.