Working Knowledge; August 1996; Scientific American Magazine; by Heidel; 1 Page(s)

Casino revenues in the U.S. during 1994 totaled $17.5 billion. Of that, 65 percent was funneled as nickels, quarters and dollar bills through slot machines. These devices may qualify as the world¿s most user-friendly computers. The collection of springs, gears, levers and weights that the inventor Charles Fey cobbled together at the turn of the century to make the Liberty Bell, which became the model for the familiar threereel slot machine, has increasingly given way to a conglomeration of microprocessors and memory chips.

Each reel can stop at 22 positions (each one displaying various symbols, such as fruit, or simply a blank space), for a total of 10,648 different combinations. When slot machines were purely mechanical, the maximum odds of a payout were therefore 10,648 to one. But the heart of a contemporary slot machine is a microprocessor programmed to generate random numbers, which can be assigned to any combination on the reels. In effect, the microprocessor dictates what the machine will display--and pay. Because many or few random numbers can be assigned to any given combination, makers of slot machines can vary the odds as desired. For the top jackpot, the odds of pulling the single right combination may be set at 10 million to one.