The Atari 2600 version of Pac-Man was reportedly developed by a single programmer over five months, and used only a 4K ROM. Despite this, Atari had ambitious plans involving the port, and manufactured 12 million cartridges despite the fact that only an estimated 10 million Atari 2600's were in use. This was done under the expectation that the game's predicted success would cause an additional two million people to go buy Atari 2600's.