 After deciding to begin work on a coin-operated version of "Spacewar", the pair, with assistance from Tuck's family, bought a PDP-11 and started working on a prototype.They spent a total of to build a single arcade machine for two players, like the original "Spacewar", deciding to price the game at ten cents per play or 25 cents for three games, with the winner of a match given a free game.They used a PDP-11/20 version of the PDP-11 (14,000), a Hewlett-Packard 1300A Electrostatic Display (3,000), and spent the remainder on the coin acceptors, joysticks, wiring, and casing.