3 Reel Slot machines are designed to look like the original mechanical slot machines. The familiar 'One Armed Bandit' is ubiquitous in American casinos, but the design has changed significantly from the original reel and drum slot machines. The original machines used a mechanical spring loaded set of reels to randomize the outcome of a pull on the crank. The ones found in casinos today uses an entirely elelctronic system where computer chips determine the random position that the reels will end up in long before they actually stop moving. In reality the 3 reel slot machines work exactly like the video slot machines, with the exception of their display.