How times change. Slots of old, as shown in the photo (top) courtesy of the University of Nevada, Las Vegas, gave ladies something to do while their men played table games. Now they are the money-making powerhouses.
Most casino players today head straight for the slots. But it wasn't always that way. Early mechanical "one-armed bandits" were simply a way to entertain the ladies of high-rolling gentlemen playing table games. But the late 70s and early 80s saw slot machines emerge as moneymaking powerhouses. In fact, since 1981, slots have been the main game in town, raking in more money for Las Vegas than their table-game counterparts. With the shift came highly sophisticated computer-controlled machines able to generate attention-grabbing bells and whistles.

Slots were once relatively simple mechanical systems with three old-style spring-loaded reels supported by a shaft, which was attached to a handle. Pulling the handle sent the reels spinning until braking mechanisms inside stopped them by locking into slotted discs, also connected to the reels.

By all outward appearances, slots today look much like those of the past but that's where the similarities end. New-generation machines are essentially independent computers, controlling every function from accepting coins and initiating play to determining game-winning combinations. Each jackpot hit is decided by the machine's computer chip programmed to generate random numbers that eventually tell the reels where to stop. The random element ensures that with each pull, players have an equal shot at hitting the jackpot.

How it works: Random number generator (RNG) software constantly produces numbers -- actually pseudorandom, based on a number-generating formula -- from one to several billion at the rate of several hundred per second. As soon as a player pulls the arm or presses the spin button to begin a game, the computer stores the next few numbers produced by the RNG.