Initially, all Intellivision games were programmed by an outside firm, APh Technological Consulting, with 19 cartridges produced before Christmas 1980. Once the Intellivision project became successful, software development was brought in-house. Mattel formed its own software development group and began hiring programmers. The original five members of that Intellivision team were Mike Minkoff, Rick Levine, John Sohl, Don Daglow, and manager Gabriel Baum. Levine and Minkoff, a long-time Mattel Toys veteran, both came over from the hand-held Mattel games engineering team. During 1981 Mattel hired programmers as fast it could. Early in 1982 Mattel Electronics relocated from Mattel headquarters to an unused industrial building. Office renovation work happened as new staff moved in. To keep these programmers from being hired away by rival Atari, their identity and work location was kept a closely guarded secret. In public, the programmers were referred to collectively as the Blue Sky Rangers.