----

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| R      | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|   | For the Quarterly Period ended March 31, 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|   | or                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| £ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|   | For the transition period from                                                                to                                                           |

| Delaware                                 | 25-1701361          |
|------------------------------------------|---------------------|
| (State or Other Jurisdiction of          | (I.R.S. Employer    |
| Incorporation or Organization)           | Identification No.) |
|                                     |                |
| 333 West San Carlos Street, Suite 700    |                |
| San Jose, California                     | 95110               |
| (Address of Principal Executive Offices) | (Zip Code)          |

| £ Large accelerated filer | R Accelerated filer | £ Non-accelerated  filer       | £ Smaller reporting company |
|--------------------------------|---------------------|-----------------------------------------------|----------------------------------|
|                           |                | (Do not check if a smaller reporting company) |                             |

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|                                                                                                | Page   |
|-----------------------------------------------------------------------------------------------------|--------|
| PART I  FINANCIAL INFORMATION                                                             |   |
| Item 1. Financial Statements (Unaudited)                                                            |   |
| Condensed Consolidated Balance Sheets as of March 31, 2011 and December 31, 2010                    | 3      |
| Condensed Consolidated Statements of Operations for the three months ended March 31, 2011 and 2010  | 4      |
| Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2011 and 2010  | 5      |
| Notes to Condensed Consolidated Financial Statements                                                | 6      |
| Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations | 15     |
| Item 3. Quantitative and Qualitative Disclosures About Market Risk                                  | 22     |
| Item 4. Controls and Procedures                                                                     | 23     |
| PART II  OTHER INFORMATION                                                                |   |
| Item 1. Legal Proceedings                                                                           | 23     |
| Item 1A. Risk Factors                                                                               | 24     |
| Item 2. Unregistered Sales of Equity Securities and Use of Proceeds                                 | 24     |
| Item 3. Defaults Upon Senior Securities                                                             | 24     |
| Item 4. (Removed and Reserved)                                                                      | 24     |
| Item 5. Other Information                                                                           | 24     |
| Item 6. Exhibits                                                                                    | 25     |
| SIGNATURES                                                                                          | 26     |
| INDEX TO EXHIBITS                                                                                   | 27     |

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|                                                                                                                                                     |   | March 31,2011 |     |   | December 31,2010 |   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|---------------|----------|--------|------------------|--------|
|                                                                                                                                                          |   |          |     |
| ASSETS                                                                                                                                                        |   |          |     |   |             |   |
| Current assets:                                                                                                                                               |   |          |     |   |             |   |
| Cash and cash equivalents                                                                                                                                     |   | $             | 39,396   |   |             | $      | 38,154 |   |
| Accounts receivable, net of allowance of $254 in both 2011 and 2010                                                                                           |   |          | 22,925   |   |             |   | 23,442 |   |
| Prepaid expenses and other current assets                                                                                                                     |   |          | 3,967    |   |             |   | 3,246 |   |
| Total current assets                                                                                                                                          |   |          | 66,288   |   |             |   | 64,842 |   |
| Property and equipment, net                                                                                                                                   |   |          | 844      |   |             |   | 797 |   |
| Non-current investments                                                                                                                                       |   |          | 718      |   |             |   | 718 |   |
| Intangible assets, net                                                                                                                                        |   |          | 1,162    |   |             |   | 1,369 |   |
| Other non-current assets                                                                                                                                      |   |          | 748      |   |             |   | 727 |   |
| Total assets                                                                                                                                                  |   | $             | 69,760   |   |             | $      | 68,453 |   |
| LIABILITIES AND STOCKHOLDERS’ EQUITY                                                                                                                    |   |          |     |   |             |   |   |   |
| Current liabilities:                                                                                                                                          |   |          |     |   |             |   |   |   |
| Current portion of long-term debt                                                                                                                             |   | $             | 86       |   |             | $      | 108 |   |
| Accounts payable                                                                                                                                              |   |          | 1,100    |   |             |   | 1,080 |   |
| Accrued compensation and related benefits                                                                                                                     |   |          | 3,927    |   |             |   | 3,964 |   |
| Accrued and other current liabilities                                                                                                                         |   |          | 2,849    |   |             |   | 2,400 |   |
| Deferred revenues                                                                                                                                             |   |          | 3,586    |   |             |   | 3,021 |   |
| Billings in excess of recognized revenues                                                                                                                     |   |          | 1,351    |   |             |   | 1,802 |   |
| Total current liabilities                                                                                                                                     |   |          | 12,899   |   |             |   | 12,375 |   |
| Long-term income taxes payable                                                                                                                                |   |          | 3,262    |   |             |   | 3,668 |   |
| Other non-current liabilities                                                                                                                                 |   |          | 1,406    |   |             |   | 1,495 |   |
| Total liabilities                                                                                                                                             |   |          | 17,567   |   |             |   | 17,538 |   |
| Commitments and contingencies (Note 13)                                                                                                                       |   |          |     |   |             |   |   |   |
| Preferred stock, $0.00015 par value, 5,000 shares authorized, no shares issued and outstanding                                                                |   |          | —  |   |             |   | — |   |
| Common stock, $0.00015 par value, 70,000 shares authorized: shares issued 31,817 and 31,276, respectively; shares outstanding 28,102 and 27,603, respectively |   |          | 4        |   |             |   | 4 |   |
| Additional paid-in-capital                                                                                                                                    |   |          | 201,865  |   |             |   | 200,144 |   |
| Treasury stock at cost, 3,715 and 3,673 shares, respectively                                                                                                  |   |          | (19,554  | )      |             |   | (19,298 | ) |
| Accumulated deficit                                                                                                                                           |   |          | (130,461 | )      |             |   | (129,884 | ) |
| Accumulated other comprehensive income (loss)                                                                                                                 |   |          | 339      |   |             |   | (51 | ) |
| Total stockholders’ equity                                                                                                                              |   |          | 52,193   |   |             |   | 50,915 |   |
| Total liabilities and stockholders’ equity                                                                                                              |   | $             | 69,760   |   |             | $      | 68,453 |   |

----

|                                                     |   | Three Months Ended March 31, |   |
|----------------------------------------------------------|--------|------------------------------|--------|
|                                                     |   | 2011                         |   |   | 2010 |   |
| Revenues:                                                |   |                         |   |   |   |   |
| Design-to-silicon-yield solutions                        |   | $                            | 10,567 |   |   | $ | 10,417 |   |
| Gainshare performance incentives                         |   |                         | 4,450  |   |   |   | 4,835 |   |
| Total revenues                                           |   |                         | 15,017 |   |   |   | 15,252 |   |
|                                                     |   |                         |   |   |   |   |   |   |
| Cost of design-to-silicon-yield solutions:               |   |                         |   |   |   |   |   |   |
| Direct costs of design-to-silicon-yield solutions        |   |                         | 5,793  |   |   |   | 6,322 |   |
| Amortization of acquired technology                      |   |                         | 156    |   |   |   | 359 |   |
| Total cost of design-to silicon-yield solutions          |   |                         | 5,949  |   |   |   | 6,681 |   |
| Gross profit                                             |   |                         | 9,068  |   |   |   | 8,571 |   |
|                                                     |   |                         |   |   |   |   |   |   |
| Operating expenses:                                      |   |                         |   |   |   |   |   |   |
| Research and development                                 |   |                         | 4,349  |   |   |   | 3,962 |   |
| Selling, general and administrative                      |   |                         | 4,745  |   |   |   | 4,579 |   |
| Amortization of other acquired intangible assets         |   |                         | 51     |   |   |   | 86 |   |
| Restructuring charges (credits)                          |   |                         | (11    | ) |   |   | 1 |   |
| Total operating expenses                                 |   |                         | 9,134  |   |   |   | 8,628 |   |
|                                                     |   |                         |   |   |   |   |   |   |
| Loss from operations                                     |   |                         | (66    | ) |   |   | (57 | ) |
| Interest and other income (expense), net                 |   |                         | (359   | ) |   |   | 262 |   |
| Income (loss) before income taxes                        |   |                         | (425   | ) |   |   | 205 |   |
| Income tax provision                                     |   |                         | 152    |   |   |   | 501 |   |
| Net loss                                                 |   | $                            | (577   | ) |   | $ | (296 | ) |
|                                                     |   |                         |   |   |   |   |   |   |
| Net loss per share — basic and diluted             |   | $                            | (0.02  | ) |   | $ | (0.01 | ) |
| Weighted average common shares — basic and diluted |   |                         | 27,810 |   |   |   | 26,929 |   |

----

|                                                                                  |   | Three Months EndedMarch 31, |    |
|--------------------------------------------------------------------------------------------|--------|-----------------------------|---------|
|                                                                                       |   | 2011                        |    |   | 2010 |   |
| Operating activities:                                                                      |   |                        |    |   |   |   |
| Net loss                                                                                   |   | $                           | (577    | ) |   | $ | (296 | ) |
| Adjustments to reconcile net loss to net cash used in operating activities:                |   |                        |    |   |   |   |   |   |
| Depreciation and amortization                                                              |   |                        | 131     |   |   |   | 271 |   |
| Stock-based compensation expense                                                           |   |                        | 1,003   |   |   |   | 1,505 |   |
| Amortization of acquired intangible assets                                                 |   |                        | 207     |   |   |   | 445 |   |
| Deferred taxes                                                                             |   |                        | (84     | ) |   |   | — |   |
| Purchases of treasury stock in connection with tax withholdings on restricted stock grants |   |                        | (256    | ) |   |   | (273 | ) |
| Changes in operating assets and liabilities:                                               |   |                        |    |   |   |   |   |   |
| Accounts receivable, net of allowances                                                     |   |                        | 517     |   |   |   | 799 |   |
| Prepaid expenses and other assets                                                          |   |                        | (621    | ) |   |   | (804 | ) |
| Accounts payable                                                                           |   |                        | 81      |   |   |   | 144 |   |
| Accrued compensation and related benefits                                                  |   |                        | (102    | ) |   |   | (799 | ) |
| Accrued and other liabilities                                                              |   |                        | 49      |   |   |   | (730 | ) |
| Deferred revenues                                                                          |   |                        | 648     |   |   |   | 183 |   |
| Billings in excess of recognized revenues                                                  |   |                        | (451    | ) |   |   | (503 | ) |
| Net cash provided by (used in) operating activities                                        |   |                        | 545     |   |   |   | (58 | ) |
| Investing activities:                                                                      |   |                        |    |   |   |   |   |   |
| Purchases of property and equipment                                                        |   |                        | (42     | ) |   |   | (37 | ) |
| Net cash used in investing  activities                                           |   |                        | (42     | ) |   |   | (37 | ) |
| Financing activities:                                                                      |   |                        |    |   |   |   |   |   |
| Proceeds from exercise of stock options                                                    |   |                        | 290     |   |   |   | — |   |
| Proceeds from employee stock purchase plan                                                 |   |                        | 429     |   |   |   | 411 |   |
| Principal payments on long-term obligations                                                |   |                        | (27     | ) |   |   | (31 | ) |
| Net cash provided by financing activities                                                  |   |                        | 692     |   |   |   | 380 |   |
| Effect of exchange rate changes on cash and cash equivalents                               |   |                        | 47      |   |   |   | (285 | ) |
| Net change in cash and cash equivalents                                                    |   |                        | 1,242   |   |   |   | — |   |
| Cash and cash equivalents, beginning of period                                             |   |                        | 38,154  |   |   |   | 34,899 |   |
| Cash and cash equivalents, end of period                                                   |   | $                           | 39,396  |   |   | $ | 34,899 |   |
| Supplemental disclosure of cash flow information:                                          |   |                        |    |   |   |   |   |   |
| Cash paid during the period for:                                                           |   |                        |    |   |   |   |   |   |
| Income Taxes                                                                               |   | $                           | 648     |   |   | $ | 811 |   |
| Interest                                                                                   |   | $                           | — |   |   | $ | 3 |   |

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|   | • | provide updated guidance on whether multiple deliverables exist, how the deliverables in an arrangement should be separated, and how the consideration should be allocated; |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | require an entity to allocate revenue in an arrangement using best estimate of selling prices (“BESP”) of deliverables if a vendor does not have vendor-specific objective evidence of fair value (“VSOE”) or third-party evidence of selling price (“TPE”); and |
|--------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | eliminate the use of the residual method and require an entity to allocate revenue using the relative selling price method. |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------|

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|                    |   | AmortizedCost |   |   | UnrealizedHoldingGains |   |    | UnrealizedHoldingLosses |   |   | FairValue |   |
|-------------------------|--------|---------------|--------|--------|------------------------|--------|---------|-------------------------|--------|--------|-----------|--------|
| Auction-rate securities |   | $             | 1,000  |   |                   | $      | — |                    |   | $      | (282      | )      |   | $ | 718 |   |

| Acquired Identifiable Intangible   |   | AmortizationPeriod(Years) |   |   | March 31, 2011Gross CarryingAmount |   |   | Accumulated Amortization |   |   | March 31, 2011Net CarryingAmount |   |
|------------------------------------|--------|---------------------------|--------|--------|------------------------------------|--------|--------|--------------------------|--------|--------|----------------------------------|--------|
| Acquired technology                |   |                      | 4-5    |   |                               | $      | 11,800 |                     |   | $      | (11,070                          | )      |   | $ | 730 |   |
| Brand name                         |   |                      | 4      |   |                               |   | 510    |                     |   |   | (510                             | )      |   |   | — |   |
| Customer relationships and backlog |   |                      | 1-6    |   |                               |   | 3,420  |                     |   |   | (3,222                           | )      |   |   | 198 |   |
| Patents and applications           |   |                      | 7      |   |                               |   | 1,400  |                     |   |   | (1,166                           | )      |   |   | 234 |   |
| Other acquired intangibles         |   |                      | 4      |   |                               |   | 255    |                     |   |   | (255                             | )      |   |   | — |   |
| Total                              |   |                      |   |   |                               | $      | 17,385 |                     |   | $      | (16,223                          | )      |   | $ | 1,162 |   |

----

| Acquired Identifiable Intangible   |   | AmortizationPeriod(Years) |   |   | December 31, 2010Gross CarryingAmount |   |   | Accumulated Amortization |   |   | December 31, 2010Net CarryingAmount |   |
|------------------------------------|--------|---------------------------|--------|--------|--------------------------------------------|--------|--------|--------------------------|--------|--------|------------------------------------------|--------|
| Acquired technology                |   |                      | 4-5    |   |                                       | $      | 11,800 |                     |   | $      | (10,915                                  | )      |   | $ | 885 |   |
| Brand name                         |   |                      | 4      |   |                                       |   | 510    |                     |   |   | (510                                     | )      |   |   | — |   |
| Customer relationships and backlog |   |                      | 1-6    |   |                                       |   | 3,420  |                     |   |   | (3,188                                   | )      |   |   | 232 |   |
| Patents and applications           |   |                      | 7      |   |                                       |   | 1,400  |                     |   |   | (1,148                                   | )      |   |   | 252 |   |
| Other acquired intangibles         |   |                      | 4      |   |                                       |   | 255    |                     |   |   | (255                                     | )      |   |   | — |   |
| Total                              |   |                      |   |   |                                       | $      | 17,385 |                     |   | $      | (16,016                                  | )      |   | $ | 1,369 |   |

| Year Ending December 31,           |   | Amount |    |
|------------------------------------|--------|--------|---------|
| 2011 (remaining nine-month period) |   | $      | 623     |   |
| 2012                               |   |   | 435     |   |
| 2013                               |   |   | 74      |   |
| 2014                               |   |   | 30      |   |
| Thereafter                         |   |   | — |   |
| Total                              |   | $      | 1,162   |   |

|                                 |   | Three MonthsEnded March 31, |   |
|-------------------------------------------|--------|-----------------------------|--------|
|                                      |   | 2011                        |   |   | 2010 |   |
| Cost of design-to-silicon-yield solutions |   | $                           | 462    |   |   | $ | 602 |   |
| Research and development                  |   |                        | 339    |   |   |   | 347 |   |
| Selling, general and administrative       |   |                        | 202    |   |   |   | 556 |   |
| Stock-based compensation expenses         |   | $                           | 1,003  |   |   | $ | 1,505 |   |

|                                                                                           |   | Stock PlansThree Months Ended March 31, |    |   | Employee Stock Purchase PlanThree Months Ended March 31, |   |
|------------------------------------------------------------------------------------------------|--------|-----------------------------------------|---------|--------|----------------------------------------------------------|--------|
|                                                                                           |   | 2011                                    |    |   | 2010                                                     |   |   | 2011 |   |   | 2010 |   |
| Expected life (in years)                                                                       |   |                                    | 4.74    |   |                                                     |   | 5.24 |   |   |   | 1.25 |   |   |   | 1.25 |   |
| Volatility                                                                                     |   |                                    | 62.2    | %      |                                                     |   | 62.8 | % |   |   | 48.7 | % |   |   | 72.6 | % |
| Risk-free interest rate                                                                        |   |                                    | 1.80    | %      |                                                     |   | 2.23 | % |   |   | 0.37 | % |   |   | 0.58 | % |
| Expected dividend                                                                              |   |                                    | — |   |                                                     |   | — |   |   |   | — |   |   |   | — |   |
| Weighted average fair value per share of options granted during the period                     |   | $                                       | 2.90    |   |                                                     | $      | 2.20 |   |   |   | — |   |   |   | — |   |
| Weighted average fair value per share of employee stock purchase plan rights during the period |   |                                    | — |   |                                                     |   | — |   |   | $ | 1.87 |   |   | $ | 1.40 |   |

----

|                                        |   | Number ofOptions(in thousands) |   |   | Weighted AverageExercise Priceper Share |   |   | Weighted AverageRemainingContractualTerm (years) |   |   | AggregateIntrinsic Value(in thousands) |   |
|---------------------------------------------|--------|--------------------------------|--------|--------|-----------------------------------------|--------|--------|--------------------------------------------------|--------|--------|----------------------------------------|--------|
| Outstanding, January 1, 2011                |   |                           | 3,453  |   |                                    | $      | 5.60   |                                             |   |   |                                   |   |   |   |
| Granted                                     |   |                           | 133    |   |                                    |   | 5.48   |                                             |   |   |                                   |   |   |   |
| Exercised                                   |   |                           | (80    | )      |                                    |   | 3.61   |                                             |   |   |                                   |   |   |   |
| Canceled                                    |   |                           | (9     | )      |                                    |   | 4.27   |                                             |   |   |                                   |   |   |   |
| Expired                                     |   |                           | (31    | )      |                                    |   | 9.39   |                                             |   |   |                                   |   |   |   |
| Outstanding, March 31, 2011                 |   |                           | 3,466  |   |                                    |   | 5.61   |                                             |   |   | 7.09                                   |   |   | $ | 6,450 |   |
| Vested and expected to vest, March 31, 2011 |   |                           | 3,219  |   |                                    |   | 5.72   |                                             |   |   | 6.98                                   |   |   | $ | 5,847 |   |
| Exercisable, March 31, 2011                 |   |                           | 1,830  |   |                                    |   | 6.79   |                                             |   |   | 5.88                                   |   |   | $ | 2,487 |   |

|                       |   | Shares(in thousands) |    |   | Weighted AverageGrant DateFair Value Per Share |   |
|----------------------------|--------|----------------------|---------|--------|------------------------------------------------|--------|
| Nonvested, January 1, 2011 |   |                 | 453     |   |                                           | $      | 7.29 |   |
| Granted                    |   |                 | — |   |                                           |   | — |   |
| Vested                     |   |                 | (150    | )      |                                           |   | 4.66 |   |
| Forfeited                  |   |                 | (2      | )      |                                           |   | 7.61 |   |
| Nonvested, March 31, 2011  |   |                 | 301     |   |                                           |   | 8.58 |   |

----

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   | Three MonthsEnded March 31, |   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |   | 2011                        |   |   | 2010 |   |
| Beginning balance                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   | $                           | 1,379  |   |   | $ | 1,619 |   |
| Restructuring charges (credits)                                                                                                                                   |   |                        | (11    | ) |   |   | 1 |   |
| Adjustments                                                                                                                                                       |   |                        | 10     |   |   |   | — |   |
| Cash payments                                                                                                                                                     |   |                        | (159   | ) |   |   | (213 | ) |
| Ending balance                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   | $                           | 1,219  |   |   | $ | 1,407 |   |

----

|                                      |   | Three MonthsEnded March 31, |   |
|------------------------------------------------|--------|-----------------------------|--------|
|                                           |   | 2011                        |   |   | 2010 |   |
| Net loss                                       |   | $                           | (577   | ) |   | $ | (296 | ) |
| Denominator for basic and diluted calculation: |   |                        |   |   |   |   |   |   |
| Weighted average common shares outstanding     |   |                        | 27,810 |   |   |   | 26,929 |   |
| Net loss per share — basic and diluted   |   | $                           | (0.02  | ) |   | $ | (0.01 | ) |

|                        |   | Three MonthsEnded March 31, |   |
|----------------------------------|--------|-----------------------------|--------|
|                             |   | 2011                        |   |   | 2010 |   |
| Outstanding options              |   |                        | 1,091  |   |   |   | 3,870 |   |
| Nonvested restricted stock units |   |                        | 90     |   |   |   | 821 |   |
| Total                            |   |                        | 1,181  |   |   |   | 4,691 |   |

|                                                                |   | Three MonthsEnded March 31, |   |
|---------------------------------------------------------------------|--------|-----------------------------|--------|
|                                                                |   | 2011                        |   |   | 2010 |   |
| Net loss                                                            |   | $                           | (577   | ) |   | $ | (296 | ) |
| Foreign currency translation adjustments, net of income tax effects |   |                        | 391    |   |   |   | (294 | ) |
| Comprehensive loss                                                  |   | $                           | (186   | ) |   | $ | (590 | ) |

----

|     |   | Three MonthsEnded March 31, |   |
|----------|--------|-----------------------------|--------|
| Customer |   | 2011                        |   |   | 2010 |   |
| A        |   |                        | 20     | % |   |   | 15 | % |
| B        |   |                        | 19     | % |   |   | 12 | % |
| C        |   |                        | 17     | % |   |   | * | % |
| D        |   |                        | 13     | % |   |   | 20 | % |

| Customer |   | March 31, 2011 |   |   | December 31, 2010 |   |
|----------|--------|----------------|--------|--------|-------------------|--------|
| A        |   |           | 11     | %      |              |   | 16 | % |
| B        |   |           | 18     | %      |              |   | 13 | % |
| C        |   |           | 11     | %      |              |   | 10 | % |
| D        |   |           | 22     | %      |              |   | 14 | % |
| E        |   |           | *      | %      |              |   | 11 | % |
| F        |   |           | *      | %      |              |   | 11 | % |

|     |   | Three MonthsEnded March 31, |   |
|---------------|--------|-----------------------------|--------|
|          |   | 2011                        |   |   | 2010 |   |
| Asia          |   | $                           | 7,558  |   |   | $ | 10,297 |   |
| Europe        |   |                        | 3,037  |   |   |   | 1,574 |   |
| United States |   |                        | 4,422  |   |   |   | 3,381 |   |
| Total         |   | $                           | 15,017 |   |   | $ | 15,252 |   |

|          |   | March 31, 2011 |   |   | December 31, 2010 |   |
|---------------|--------|----------------|--------|--------|-------------------|--------|
| United States |   | $              | 1,795  |   |              | $      | 1,935 |   |
| Europe        |   |           | 114    |   |              |   | 121 |   |
| Asia          |   |           | 97     |   |              |   | 110 |   |
| Total         |   | $              | 2,006  |   |              | $      | 2,166 |   |

| Level 1 — | Inputs are quoted prices in active markets for identical assets or liabilities. |
|-----------------|---------------------------------------------------------------------------------|

----

| Level 2 — | Inputs are quoted prices for similar assets or liabilities in an active market, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable and market-corroborated inputs which are derived principally from or corroborated by observable market data. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|            |                                                                                                                                                                                                                                                                                                                                          |
| Level 3 — | Inputs are derived from valuation techniques in which one or more significant inputs or value drivers are unobservable.                                                                                                                                                                                                                       |

| Assets                    |   | Total  |   |   | Quoted Prices inActive Markets forIdentical Assets(Level 1) |   |    | Significant OtherObservable Inputs(Level 2) |   |   | SignificantUnobservable Inputs(Level 3) |   |
|---------------------------|--------|--------|--------|--------|-------------------------------------------------------------|--------|---------|---------------------------------------------|--------|--------|-----------------------------------------|--------|
| Money market mutual funds |   | $      | 25,315 |   |                                                        | $      | 25,315  |                                        |   | $      | —                                 |   |   | $ | — |   |
| Auction-rate securities   |   |   | 718    |   |                                                        |   | — |                                        |   |   | —                                 |   |   |   | 718 |   |
| Total                     |   | $      | 26,033 |   |                                                        | $      | 25,315  |                                        |   | $      | —                                 |   |   | $ | 718 |   |

| Assets                    |   | Total  |   |   | Quoted Prices inActive Markets forIdentical Assets(Level 1) |   |    | Significant OtherObservable Inputs(Level 2) |   |   | SignificantUnobservable Inputs(Level 3) |   |
|---------------------------|--------|--------|--------|--------|-------------------------------------------------------------|--------|---------|---------------------------------------------|--------|--------|-----------------------------------------|--------|
| Money market mutual funds |   | $      | 25,304 |   |                                                        | $      | 25,304  |                                        |   | $      | —                                 |   |   | $ | — |   |
| Auction-rate securities   |   |   | 718    |   |                                                        |   | — |                                        |   |   | —                                 |   |   |   | 718 |   |
| Total                     |   | $      | 26,022 |   |                                                        | $      | 25,304  |                                        |   | $      | —                                 |   |   | $ | 718 |   |

----

|   | • | Total revenues for the three months ended March 31, 2011 was $15.0 million, a decrease of $0.3 million, or 2%, compared to total revenues of $15.3 million for the three months ended March 31, 2010. Design-to-silicon-yield solutions revenues for the three months ended March 31, 2011 was $10.6 million, an increase of $0.1 million, or 1%, compared to $10.5 million for the three months ended March 31, 2010. The increase in Design-to-silicon-yield solutions revenues was primarily the result of increased bookings. Gainshare performance incentives revenues for the three months ended March 31, 2011 was $4.4 million, a decrease of $0.4 million, or 8%, compared to gainshare performance incentive revenues of $4.8 million for the three months ended March 31, 2010.  This decrease was primarily due to lower reported wafer production by a customer. |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

|   | • | Net loss for the three months ended March 31, 2011 was $(577,000), compared to $(296,000) for the three months ended March 31, 2010. The decrease in net loss was primarily attributable to a decrease in revenues and an increase in operating expenses during the three months ended March 31, 2011. |
|--------|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | Net loss per basic and diluted share was $(0.02) for the three months ended March 31, 2011 compared to $(0.01) for the three months ended March 31, 2010, an increase in net loss of $(0.01) per basic and diluted share. |
|--------|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | Cash, cash equivalents and non-current investments increased $1.2 million from $38.9 million at December 31, 2010 to $40.1 million at March 31, 2011, primarily due to cash from operating and financing activities during the period. |
|--------|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

|   | • | provide updated guidance on whether multiple deliverables exist, how the deliverables in an arrangement should be separated, and how the consideration should be allocated; |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | require an entity to allocate revenue in an arrangement using best estimate of selling prices (“BESP”) of deliverables if a vendor does not have vendor-specific objective evidence of fair value (“VSOE”) or third-party evidence ofselling price (“TPE”); and |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | • | eliminate the use of the residual method and require an entity to allocate revenue using the relative selling price method. |
|--------|---------|-----------------------------------------------------------------------------------------------------------------------------|

----

|                                              |   | Three Months EndedMarch 31, |    |
|---------------------------------------------------|--------|-----------------------------|---------|
|                                              |   | 2011                        |    |   | 2010 |   |
| Revenues:                                         |   |                        |    |   |   |   |
| Design-to-silicon-yield solutions                 |   |                        | 70      | % |   |   | 68 | % |
| Gainshare performance incentives                  |   |                        | 30      |   |   |   | 32 |   |
| Total revenues                                    |   |                        | 100     | % |   |   | 100 | % |
| Cost of design-to-silicon-yield solutions:        |   |                        |    |   |   |   |   |   |
| Direct costs of design-to-silicon-yield solutions |   |                        | 39      |   |   |   | 42 |   |
| Amortization of acquired technology               |   |                        | 1       |   |   |   | 2 |   |
| Total cost of design-to-silicon-yield solutions   |   |                        | 40      |   |   |   | 44 |   |
| Gross margin                                      |   |                        | 60      |   |   |   | 56 |   |
| Operating expenses:                               |   |                        |    |   |   |   |   |   |
| Research and development                          |   |                        | 29      |   |   |   | 26 |   |
| Selling, general and administrative               |   |                        | 32      |   |   |   | 30 |   |
| Amortization of other acquired intangible assets  |   |                        | — |   |   |   | 1 |   |
| Restructuring charges                             |   |                        | — |   |   |   | — |   |
| Total operating expenses                          |   |                        | 61      |   |   |   | 57 |   |
| Loss from operations                              |   |                        | (1      | ) |   |   | (1 | ) |
| Interest and other income (expense), net          |   |                        | (2      | ) |   |   | 2 |   |
| Income (loss) before taxes                        |   |                        | (3      | ) |   |   | 1 |   |
| Income tax provision                              |   |                        | 1       |   |   |   | 3 |   |
| Net loss                                          |   |                        | (4      | )% |   |   | (2 | )% |

----

|                                   |   |                                     |   |   |     |   |   |   |   |   | Three Months Ended March 31, |   |
|----------------------------------------|--------|------------------------------------------|--------|--------|----------|--------|--------|--------|--------|--------|------------------------------|--------|
|                              |   |   Three Months Ended March 31, |   |   |   $ |   |   | %      |   |   | 2011% of                     |   |   | 2010% of |   |
| Revenues                               |   | 2011                                     |   |   | 2010     |   |   | Change |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages) |   |                                     |   |
| Design-to-silicon-yield solutions      |   | $                                        | 10,567 |   |     | $      | 10,417 |   |   | $      | 150                          |   |   |   | 1 | % |   |   | 70 | % |   |   | 68 | % |
| Gainshare performance incentives       |   |                                     | 4,450  |   |     |   | 4,835  |   |   |   | (385                         | )      |   |   | (8 | )% |   |   | 30 | % |   |   | 32 | % |
| Total                                  |   | $                                        | 15,017 |   |     | $      | 15,252 |   |   | $      | (235                         | )      |   |   | (2 | )% |   |   | 100 | % |   |   | 100 | % |

|                                              |   |                         |   |   |   |   |   |   |   |   | Three Months Ended March 30, |   |
|---------------------------------------------------|--------|------------------------------|--------|--------|--------|--------|--------|--------|--------|--------|------------------------------|--------|
|                                              |   | Three Months Ended March 31, |   |   | $      |   |   | %      |   |   | 2011% of                     |   |   | 2010% of |   |
| Cost of Design-to-Silicon-Yield Solutions         |   | 2011                         |   |   | 2010   |   |   | Change |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages)            |   |                         |   |   |   |   |   |   |   |   |                         |   |   |   |   |   |   |   |
| Direct costs of design-to-silicon-yield solutions |   | $                            | 5,793  |   |   | $      | 6,322  |   |   | $      | (529                         | )      |   |   | (8 | )% |   |   | 39 | % |   |   | 42 | % |
| Amortization of acquired technology               |   |                         | 156    |   |   |   | 359    |   |   |   | (203                         | )      |   |   | (56 | )% |   |   | 1 | % |   |   | 2 | % |
| Total                                             |   | $                            | 5,949  |   |   | $      | 6,681  |   |   | $      | (732                         | )      |   |   | (11 | )% |   |   | 40 | % |   |   | 44 | % |

----

|                                   |   |                                |   |   |     |   |   |     |   |   | Three Months Ended March 31, |   |
|----------------------------------------|--------|-------------------------------------|--------|--------|----------|--------|--------|----------|--------|--------|------------------------------|--------|
|                              |   |   Three Months Ended March 31, |   |   |   $ |   |   |   % |   |   | 2011% of                     |   |   | 2010% of |   |
| Research and Development               |   | 2011                                |   |   | 2010     |   |   | Change   |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages) |   |                                |   |   |     |   |   |     |   |   |                         |   |   |   |   |   |   |   |
| Research and development               |   | $                                   | 4,349  |   |     | $      | 3,962  |     |   | $      | 387                          |   |   |   | 10 | % |   |   | 29 | % |   |   | 26 | % |

|                                   |   |                                |   |   |     |   |   |     |   |   | Three Months Ended March 31, |   |
|----------------------------------------|--------|-------------------------------------|--------|--------|----------|--------|--------|----------|--------|--------|------------------------------|--------|
|                              |   |   Three Months Ended March 31, |   |   |   $ |   |   |   % |   |   | 2011% of                     |   |   | 2010% of |   |
| Selling, General and Administrative    |   | 2011                                |   |   | 2010     |   |   | Change   |   |   | Change                       |   |   | Revenue |   |   | Revenue |   |
| (in thousands, except for percentages) |   |                                |   |   |     |   |   |     |   |   |                         |   |   |   |   |   |   |   |
| Selling, general and administrative    |   | $                                   | 4,745  |   |     | $      | 4,579  |     |   | $      | 166                          |   |   |   | 4 | % |   |   | 32 | % |   |   | 30 | % |

|                                             |   |                                |   |   |            |   |   |            |   |   | Three Months Ended March 31, |   |
|--------------------------------------------------|--------|-------------------------------------|--------|--------|-----------------|--------|--------|-----------------|--------|--------|------------------------------|--------|
|                                        |   |   Three Months Ended March 31, |   |   |     $ |   |   |     % |   |   | 2011% of                     |   |   | 2010% of |   |
| Amortization of Other Acquired Intangible Assets |   | 2011                                |   |   | 2010            |   |   | Change          |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages)           |   |                                |   |   |            |   |   |            |   |   |                         |   |   |   |   |   |   |   |
| Amortization of other acquired intangible assets |   | $                                   | 51     |   |            | $      | 86     |            |   | $      | (35                          | )      |   |   | (41 | )% |   |   | — | % |   |   | 1 | % |

|                                   |   |                         |   |   |   |   |   |   |   |   | Three Months Ended March 31, |   |
|----------------------------------------|--------|------------------------------|--------|--------|--------|--------|--------|--------|--------|--------|------------------------------|--------|
|                                   |   | Three Months Ended March 31, |   |   | $      |   |   | %      |   |   | 2011% of                     |   |   | 2010% of |   |
| Restructuring Charges                  |   | 2011                         |   |   | 2010   |   |   | Change |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages) |   |                         |   |   |   |   |   |   |   |   |                         |   |   |   |   |   |   |   |
| Restructuring charges (credits)        |   | $                            | (11    | )      |   | $      | 1      |   |   | $      | (12                          | )      |   |   | (1,238 | )% |   |   | — | % |   |   | — | % |

|                                   |   |                         |   |   |   |   |   |   |   |   | Three Months Ended March 31, |   |
|----------------------------------------|--------|------------------------------|--------|--------|--------|--------|--------|--------|--------|--------|------------------------------|--------|
|                                   |   | Three Months Ended March 31, |   |   | $      |   |   | %      |   |   | 2011% of                     |   |   | 2010% of |   |
| Interest and Other Income, net         |   | 2011                         |   |   | 2010   |   |   | Change |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages) |   |                         |   |   |   |   |   |   |   |   |                         |   |   |   |   |   |   |   |
| Interest and other income (loss), net  |   | $                            | (359   | )      |   | $      | 262    |   |   | $      | (621                         | )      |   |   | (237 | )% |   |   | 2 | % |   |   | 2 | % |

----

|                                   |   |                         |   |   |   |   |   |   |   |   | Three Months Ended March 31, |   |
|----------------------------------------|--------|------------------------------|--------|--------|--------|--------|--------|--------|--------|--------|------------------------------|--------|
|                                   |   | Three Months Ended March 31, |   |   | $      |   |   | %      |   |   | 2011% of                     |   |   | 2010% of |   |
| Income Tax Provision                   |   | 2011                         |   |   | 2010   |   |   | Change |   |   | Change                       |   |   | Revenues |   |   | Revenues |   |
| (in thousands, except for percentages) |   |                         |   |   |   |   |   |   |   |   |                         |   |   |   |   |   |   |   |
| Income tax provision                   |   | $                            | 152    |   |   | $      | 501    |   |   | $      | (349                         | )      |   |   | 70 | % |   |   | 1 | % |   |   | 3 | % |

----

| Contractual obligations         |   | 2011(nine monthsremaining) |   |   | 2012   |   |    | 2013   |   |   | 2014    |   |   | Total  |    |
|---------------------------------|--------|----------------------------|--------|--------|--------|--------|---------|--------|--------|--------|---------|--------|--------|--------|---------|
| Debt principal (1)              |   | $                          | 85     |   |   | $      | — |   |   | $      | — |   |   | $      | — |   |   | $ | 85 |   |
| Debt interest (1)               |   |                       | 1      |   |   |   | — |   |   |   | — |   |   |   | — |   |   |   | 1 |   |
| Operating lease obligations (2) |   |                       | 2,680  |   |   |   | 2,402   |   |   |   | 1,729   |   |   |   | 48      |   |   |   | 6,859 |   |
| Purchase obligations (3)        |   |                       | 2,300  |   |   |   | 333     |   |   |   | — |   |   |   | — |   |   |   | 2,633 |   |
| Total (4)                       |   | $                          | 5,066  |   |   | $      | 2,735   |   |   | $      | 1,729   |   |   | $      | 48      |   |   | $ | 9,578 |   |

| (1)   | Amount represents the repayment of a €400,000 loan with a variable interest rate based on the EURIBOR plus 160 basis points. |
|-----------------|------------------------------------------------------------------------------------------------------------------------------------|

| (2)   | Operating lease amounts include minimum rental payments under our operating leases for our office facilities, as well as computers, office equipment, and vehicles that we utilize under lease agreements. These minimum rental payments include payments on those facilities abandoned as part of the restructuring activities. These agreements expire at various dates through 2014. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (3)   | Purchase obligations consist of agreements to purchase goods and services entered in the ordinary course of business. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------|

| (4)   | The contractual obligation table above excludes liabilities for uncertain tax positions of $3.3 million, which are not practicable to assign to any particular years, due to the inherent uncertainty of the tax positions.  See Note 8 of “Notes to Condensed Consolidated Financial Statements (Unaudited)” for further discussion.   |
|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

| ·   | Hiring personnel with requisite experience for non-routine or complex transactions, including with respect to the application of generally accepted accounting principles for percentage of completion contracts, certain multi-element revenue arrangements, and stock-based compensation transactions; |
|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Expanding controls to include identification of non-routine and complex transactions for increased periodic and on-going review by high-level personnel with the requisite expertise; |
|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Implementing procedures to ensure that our revenue controls are enhanced to include specific consideration of the accounting for contract costs and the cost estimation process for the Company's design-to-silicon yield services contracts; and, |
|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Providing on-going training of our employees on generally accepted accounting principles in general, and existing and new policies and procedures around revenue and stock-based compensation in particular. |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

|      Period                  |   | TotalNumber ofSharesPurchased (2) |    |   |      AveragePrice PaidPer Share |   |    | Total Number ofSharesPurchased asPart of PubliclyAnnounced Plansor Programs (1) |   |   |   Approximate DollarValue of Shares thatMay Yet BePurchased Under thePlans or Programs(1) |   |
|-------------------------------------------------------|--------|-----------------------------------|---------|--------|------------------------------------------------|--------|---------|---------------------------------------------------------------------------------|--------|--------|------------------------------------------------------------------------------------------------|--------|
| Month #1 (January 1, 2011 through January 31, 2011)   |   |                              | — |   |                                           | $      | — |                                                                            |   |   | —                                                                                        |   |   | $ | 9,954 |   |
| Month #2 (February 1, 2011 through February 28, 2011) |   |                              | 2       |   |                                           |   | 6.03    |                                                                            |   |   | 2                                                                                              |   |   | $ | 9,944 |   |
| Month #3 (March 1, 2011 through March 31, 2011)       |   |                              | 41      |   |                                           |   | 5.96    |                                                                            |   |   | 41                                                                                             |   |   | $ | 9,698 |   |
| Total                                                 |   |                              | 43      |   |                                           | $      | 5.97    |                                                                            |   |   | 43                                                                                             |   |   |   |   |   |

| (1)   | On October 29, 2007, the Board of Directors approved a program to repurchase up to $10.0 million of the Company’s common stock on the open market. The right to repurchase stock under this program expired on October 29, 2010. An amendment to this repurchase program was approved by the Board of Directors on October 19, 2010 that extended the program's term for two more years to October 29, 2012 and increased the aggregate amount available for repurchase under the program to $10.0 million. As of March 31, 2010, 2.7 million shares were repurchased at the average price of $3.50 per share under this program and $9.70 million remained available for repurchases. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (2)   | Included in the shares indicated in the table above are shares that the Company withheld through net share settlements to cover tax withholding obligations upon the vesting of restricted stock unit awards under the Company’s equity compensation plans. |
|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

| ExhibitNumber |  Description                                                                                                           |
|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 31.01         | Certification of the Chief Executive Officer pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 31.02         | Certification of the Chief Financial Officer pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 32.01         | Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. *                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 32.02         | Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. *                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |

|  * | As contemplated by SEC Release No. 33-8212, these exhibits are furnished with this Quarterly Report on Form 10-Q and are not deemed filed with the Securities and Exchange Commission and are not incorporated by reference in any filing of PDF Solutions, Inc. under the Securities Act of 1933 or the Securities Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general incorporation language in any filings. |
|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

----

|                     | PDF SOLUTIONS, INC. |                                  |
|--------------------------|---------------------|---------------------------------------|
|                     |                |                                  |   |
|                     |                |                                  |   |
| Date:  May 10, 2011 | By:                 | /s/ JOHN K. KIBARIAN             |   |
|                     |                | John K. Kibarian                      |   |
|                     |                | President and Chief Executive Officer |   |
|                     |                | (Principal Executive Officer)         |   |

| Date:  May 10, 2011 | By:    | /s/ JOY E. LEO                                                  |   |
|--------------------------|--------|----------------------------------------------------------------------|--------|
|                     |   | Joy E. Leo                                                           |   |
|                     |   | EVP, Chief Administration Officer and Acting Chief Financial Officer |
|                     |   | (Principal Financial Officer)                                        |   |

----

| ExhibitNumber |  Description                                                                                                           |
|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 31.01         | Certification of the Chief Executive Officer pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 31.02         | Certification of the Chief Financial Officer pursuant to Exchange Act Rules 13a-14(a) and 15d-14(a), as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 32.01         | Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. *                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| 32.02         | Certification pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. *                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |

|  * | As contemplated by SEC Release No. 33-8212, these exhibits are furnished with this Quarterly Report on Form 10-Q and are not deemed filed with the Securities and Exchange Commission and are not incorporated by reference in any filing of PDF Solutions, Inc. under the Securities Act of 1933 or the Securities Exchange Act of 1934, whether made before or after the date hereof and irrespective of any general incorporation language in any filings. |
|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|