Slot Machine: Technology: Random Number Generator

It is a common belief that the odds on a machine have something to do with the number of each kind of symbol on each reel, but in modern slot machines this is no longer the case. Modern slot machines are computerized, so that the odds are whatever they are programmed to be. In modern slot machines, the reels and lever are present for historical and entertainment reasons only. The positions the reels will come to rest on are chosen by a Random Number Generator (RNG) contained in the machine's software.

The RNG is constantly generating random numbers, at a rate of hundreds or maybe thousands per second. As soon as the lever is pulled or the "Play" button is pressed, the most recent random number is used to determine the result. This means that the result varies depending on exactly when the game is played. A fraction of a second earlier or later, and the result would be different.

Some professional gamblers observe that the RNG does not actually generate random numbers. Indeed, all RNG (also called Pseudorandom Number Generators or PRNGs) will eventually repeat their number sequence. This behavior is due to poor programming, as it is relatively easy to build PRNGs with periods so long no computer could complete a single period in the expected lifetime of the universe. Having access to the PRNG code and seed values Ronald Dale Harris, a former slot machine programmer, discovered equations for specific gambling games like Keno that allowed them to predict what the next set of selected numbers would be based on the previous games played.

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