Macintosh Business Unit (informally known as Mac BU or MacBU) is an operating unit of Microsoft Corporation that prouces software for the Apple Inc. Macintosh platform. Formed on January 7, 1997, it is today situated within Microsoft's Specialized Devices and Applications Group inside the Entertainment and Devices Division. The Mac BU is one of the largest developers of Macintosh software outside of Apple Inc., currently employing more than 180 people and having an estimated yearly revenue of $350 million.