After agreeing on an initial idea, Bushnell and Dabney began designing a prototype based on a Data General Nova. Initially, they were joined by Larry Bryan, a computer programmer who also worked at Ampex. Over the summer, the three made plans for developing the game. Bushnell and Dabney put US$100 each into a partnership, named Syzygy by Bryan, in order to purchase components. They soon ran into difficulties with their planned design: the computer was not powerful enough to run multiple simultaneous games and refresh the monitors as fast as was needed to make the games playable. Bryan realized this soon after starting work on the project in August 1970 while trying to design the code needed to run the games, and he left the project before Syzygy was officially formed without ever contributing any money. Bushnell and Dabney continued working on the design for several more months. The pair attempted to reduce the load on the computer by replacing subroutines—such as displaying the background stars—with specialized hardware, but it proved insufficient; even reducing the number of monitors was not enough. By the end of November 1970, Bushnell decided to abandon the project as untenable; Dabney had stopped working on the design a while before. It is unclear if the pair were aware that Data General had demonstrated a more powerful variant of the Nova, sold for US$8,000, running a single game of "Spacewar!" at the Fall Joint Computer Conference in December 1968, though that solution would have been too expensive for an arcade game, which typically cost US$1,000 at the time. Unable to put the game idea out of his mind, however, Bushnell soon thought of a way to manipulate the video signal on the screen with hardware without a computer having to control it, and from there the pair came up with the idea of building hardware components to handle parts of the game on behalf of the computer.