Patent US 4,099,722

An electronic slot machine employing solid state circuitry of modular design, simplifying maintenance to the tasks of module replacement, changing lamps and possibly clearing a coin jam. A coin detector creates a jam condition upon any malfunction during coin insertion. A high frequency clock drives a multistage counter which is decoupled from the clock either upon insertion of the proper number of coins (in an automatic machine) or upon the operation of the conventional operating handle which is activated by coin entry. A stepping motor steps the reels, having a plurality of symbols, while stepping the count in the counter to zero, which count deenergizes the stepping motors. Three-bit binary codes are generated representing the reel symbols in the final output position for any type of machine from three symbol center line to five line criss-cross models. Logical gates decode the symbol combination indicating a payout (if any) and size of payout which is stored in counter means stepped downwardly as coins are dispensed. Test routines and security and function evaluation (SAFE) circuitry are provided to assure proper operation and to positively identify the malfunction, which is presented on a visual display. Malfunctions or security breaches are checked and lock the machine and flash a malfunction lamp, the malfunctions being isolated and identified by visual display. Machine identification number, coin quantities, payouts and malfunctions are stored and polled by computer which extracts machine status, security breach, malfunction, security breach, coin handle, coin drop and other coin flow data.