Windows 7, a major release of the Microsoft Windows operating system, was available in six different editions: Starter, Home Basic, Home Premium, Professional, Enterprise and Ultimate. Only Home Premium, Professional, and Ultimate were widely available at retailers.[1] The other editions focus on other markets, such as the software development world or enterprise use. All editions support 32-bit IA-32 CPUs and all editions except Starter support 64-bit x64 CPUs. 64-bit installation media are not included in Home-Basic edition packages, but can be obtained separately from Microsoft.