markets related to unstable economic conditions and increased competition in the lower-end market segments. Offsetting these declines were increases in sales of our notebook GPU, high-end desktop GPU and memory products.  The growth in sales of notebook GPU products was driven by a continuing shift in the market demand towards notebook PCs from desktop PCs as reported in the December 2010 PC Graphics Report from Mercury Research.  The growth in memory sales and high-end desktop GPU products was driven primarily by the launch of our new generation of GPUs with Fermi architecture.



PSB. PSB revenue increased by 60% to $818.6 million for fiscal year 2011 as compared to $510.0 million for fiscal year 2010.  Both the ASP and unit shipments of professional workstation products increased due to the recovery of corporate spending following the economic recession that began during fiscal year 2009.   In addition, we saw strong growth in our Tesla products from the prior year as our high performance computing line gained traction fueled by the Fermi architecture release.  



CPB.  CPB revenue increased by 27% to $197.6 million for fiscal year 2011 as compared to $156.0 million for fiscal year 2010.  This increase in CPB revenue was primarily driven by sales growth from ramp up in our Tegra 2 products, offset by decreases in embedded product revenues primarily related to the entertainment markets.  Revenue from development arrangements and royalties from game console-related products increased slightly in fiscal year 2011 when compared to fiscal year 2010.



Concentration of Revenue

 

We generated 78%, 83% and 84% of our total revenue for fiscal years 2012, 2011 and 2010, respectively, from sales to customers outside the United States and other Americas. Revenue by geographic region is allocated to individual countries based on the location to which the products are initially billed even if the foreign contract equipment manufacturers, add-in board and motherboard manufacturers’ revenue is attributable to end customers in a different location.



Revenue from significant customers, those representing 10% or more of total revenue for the respective dates, is summarized as follows: 



Gross Profit and Gross Margin

 

Gross profit consists of total revenue, net of allowances, less cost of revenue. Cost of revenue consists primarily of the cost of semiconductors purchased from subcontractors, including wafer fabrication, assembly, testing and packaging, manufacturing support costs, including labor and overhead associated with such purchases, final test yield fallout, inventory and warranty provisions and shipping costs. Cost of revenue also includes development costs for license, service arrangements and stock-based compensation related to personnel associated with manufacturing.

 

Gross margin is the percentage of gross profit to revenue.  Our gross margin was 51.4%, 39.8% and 35.4% for fiscal years 2012, 2011 and 2010, respectively.  Our gross margin is significantly impacted by the mix of products we sell and can vary in any period depending on that product mix.



Our strategy for improving our gross margin relies upon delivering competitive