A dice displaying apparatus for a computer game machine includes a trackball operable by each player. Rolling speeds of two dice are derived from an amount and direction of operation of the trackball. Rolling angles of the dice are also derived from the amount and direction of operation of the trackball,...http://www.google.com.au/patents/US5263715?utm_source=gb-gplus-sharePatent US5263715 - Dice displaying apparatus for a computer game machine
