Modern Slots

First slots machines were mechanical devices. The selection principle was an independent spinning of each reel which were vertically disposed on a common axis. When a player activated the machine by pulling a lever-like handle, the reels were caused to revolve freely. Payoffs were based on the horizontal alignment of symbols after the reels come to rest.

The odds of such machine were determined by the number of reels and symbols on each reel. The Liberty Bell had three reels each with ten symbols and every symbol on the reel had an equal probability of showing on the payline. The chance that a symbol appear on the paying was 1 in 10. So, the odds against hitting the jackpot on the Liberty Bell were 1,000 to 1, because account for 10 x 10 x 10 = 1,000 possible combinations.

That's how the original slot machines worked.

Today's slot machines are much more sophisticated. They are computer driven, so everything - the jackpots, sound effects and even the reels themselves - are controlled by microprocessors, and the main difference from mechanical slots is that in modern slots, each stop does not have the same probability of showing on the payline.

Computer chip generates random numbers when you press the "Spin" button or pull the handle, than the computer uses a mapping technique to convert the large number into a smaller number or integer that is mapped to the stops to show you either a winning combination or a losing one.

We won't even try to explain it better than Tom Harris did. It is the best articles on the net about slots, I suppose. Read them to find out what is "The modern One-armed Bandit" and how it works.

Read also:

• Slots Variations - a list of parameters, that can be used while describing a slot machine.
• Slot Machine Types - the main types of slots you can find both in land-based and online Casinos.