Abstract: A reel-type slot machine includes a microprocessor driven game control circuit for randomly selecting a game result. Three reel assemblies each include a symbol-bearing display reel driven by a stepper motor for displaying game symbols corresponding to the game result. A series of signals representing potential game results is repetitively generated within the game control circuits. Upon user actuation of a spin switch one of the game results is randomly selected for application to a look-up table wherein the corresponding three game symbols to be displayed are identified. The number of repetitions of a potential game result in the series establishes a time window of availability for the result, and hence the probability of that game result being selected. After the three game symbols have been identified, the display reels are driven by their respective stepper motors to display the game symbols. Optional ramp-up and ramp-down circuits provide improved stopping accuracy.

Abstract: A reel-type slot machine includes a microprocessor driven game control circuit for randomly selecting a game result. Three reel assemblies each include a symbol-bearing display reel driven by a stepper motor for displaying game symbols corresponding to the game result. A random number generator within the game control circuit generates a random number within a predetermined range of random numbers for application to a look-up table wherein a game result consisting of three game symbols is identified. Each potential game result is associated with a subset of random numbers within the total range of random numbers. The size of the subset determines the probability of the game result occurring. An undesired game result may be avoided by providing no corresponding subset. After the game result symbols have been identified, the display reels are driven by the stepper motors to display the game symbols. Optional ramp-up and ramp-down circuits provide improved stepping accuracy.

Abstract: A reel-type slot machine includes a microprocessor driven game control circuit for randomly determining a game result and three reel assemblies each including a symbol-bearing reel driven by a stepper motor for displaying the game results. The stepper motors each include a permanent magnet rotor and four stator windings which respond to quadrature phase motor drive signals generated by the game control circuit to incrementally rotate the reels. A reel motion monitoring circuit senses back EMF on each stator winding to generate an error signal which inhibits play in the event a motor fails to respond to an applied drive signal or a reel is moved by tampering.