The Liberty Bell machine was so popular that it was copied by many slot machine manufacturers. Mathematician Michael Shackleford revealed the pars for one commercial slot machine, an original International Gaming Technology Red White and Blue machine. It was sofun and I loved having an excuse to wear my dress. "Slot Machines: The Big Gamble". These used a number of features to ensure the payout was controlled within the limits of the gambling legislation. Terminology edit Bonus is a special feature of the particular game theme, which is activated when certain symbols appear in a winning combination. Ellis 10 and State. The minimum theoretical payout percentage varies among jurisdictions and is typically established by law or regulation.