Three months ended December 31, 2009 compared with three months ended December 31, 2008 EDD revenue decreased reflecting a $295 million or 12% decline in Xbox 360 platform and PC game revenue. This decrease was due mainly to decreased revenue from Xbox 360 video games, decreased Xbox 360 consoles sold, and decreased revenue per console, offset in part by increased Xbox LIVE revenue. The decreased revenue from Xbox 360 video games was due primarily to the release of two significant games in the second quarter of the prior year. We shipped 5.2 million Xbox 360 consoles during the second quarter of fiscal year 2010, compared with 6.0 million Xbox 360 consoles during the second quarter of fiscal year 2009. The decreased revenue per console resulted from price reductions during the past 12 months. Non-gaming revenue decreased $59 million or 8%, primarily reflecting decreased sales of Zune digital music and entertainment devices and Windows Mobile device platforms. Foreign currency exchange rates accounted for a $49 million or two percentage point increase in revenue.
EDD operating income increased due to reduced operating expenses. Cost of revenue decreased $478 million or 23%, primarily due to lower Xbox 360 console costs, offset in part by increased royalties to partners related to increased Xbox LIVE transactions. Sales and marketing expenses decreased $75 million or 15%, primarily due to decreased marketing for the Xbox 360 platform. Research and development expenses decreased $50 million or 10%, primarily reflecting decreased headcount-related expenses and third-party development and programming costs.
Six months ended December 31, 2009 compared with six months ended December 31, 2008 EDD revenue decreased reflecting decreases in Xbox 360 platform and PC game revenue, as well as decreased revenue from the non-gaming portion of the business. Xbox 360 platform and PC game revenue decreased by $199 million or 5% due mainly to decreased Xbox 360 consoles sold, decreased revenue per console, and decreased revenue from Xbox 360 games, offset in part by increased Xbox LIVE revenue. We shipped 7.3 million Xbox 360 consoles during the first half of fiscal year 2010, compared with 8.3 million Xbox 360 consoles during the first half of fiscal year 2009. The decreased revenue per console resulted from price reductions during the past 12 months. The decreased revenue from Xbox 360 video games was due primarily to the release of two significant games in the second quarter of the prior year. Non-gaming revenue decreased $157 million or 11%, primarily reflecting decreased sales of Zune digital music and entertainment devices and Window Mobile device platforms.
EDD operating income increased due to reduced operating expenses. Cost of revenue decreased $581 million or 19%, primarily due to lower Xbox 360 console costs, offset in part by increased royalties to partners related to increased Xbox LIVE transactions. Sales and marketing expenses decreased by $59 million or 8%, primarily due to decreased marketing for the Xbox 360 platform. Research and development expenses decreased $113 million or 12%, primarily reflecting decreased headcount-related expenses and third-party development and programming costs.