EDD revenue increased primarily reflecting higher Xbox 360 platform revenue. Xbox 360 platform revenue grew $2.7 billion or 48%, led by increased volumes of Xbox 360 consoles, sales of Kinect sensors, and higher Xbox LIVE revenue. We shipped 13.7 million Xbox 360 consoles during fiscal year 2011, compared with 10.3 million Xbox 360 consoles during fiscal year 2010.
EDD operating income increased primarily reflecting revenue growth, offset in part by higher cost of revenue. Cost of revenue increased $1.8 billion or 49% primarily reflecting higher volumes of Xbox 360 consoles and Kinect sensors sold, and increased royalty costs resulting from increased sales of Xbox LIVE digital content. Research and development expenses increased $119 million or 12%, primarily reflecting higher headcount-related costs. Sales and marketing expenses grew $90 million or 12% primarily reflecting increased Xbox 360 platform marketing activities.