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.