Exhibit 99.1

FIRST AMENDMENT TO CREDIT AGREEMENT

THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of March 14, 2011, is entered into by and among DDI GLOBAL CORP., a California corporation (“Global”), DDI SALES CORP., a Delaware corporation (“Sales”), DDI NORTH JACKSON CORP., an Ohio corporation (“North Jackson”), DDI MILPITAS CORP., a Delaware corporation (“Milpitas”), DDI DENVER CORP., a Colorado corporation (“Denver”), DDI CLEVELAND CORP., an Ohio corporation (“Cleveland”), DDI TORONTO CORP., an entity organized under the laws of Ontario (“Toronto”; each of Global, Sales, North Jackson, Milpitas, Denver, Cleveland and Toronto shall be a “Borrower”, and collectively such entities shall be the “Borrowers”), the other Loan Parties (as defined below) party hereto, the Lenders (as defined below) party hereto, JPMORGAN CHASE BANK, N.A., as administrative agent for the Lenders (in such capacity, “Administrative Agent”), and JPMORGAN CHASE BANK, N.A., TORONTO BRANCH, as Canadian administrative agent for the Canadian Lenders (in such capacity, “Canadian Administrative Agent” and, together with Administrative Agent collectively, “Agents”)

RECITALS

AGREEMENT

NOW, THEREFORE, in consideration of the foregoing and the mutual covenants herein contained, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereby agree as follows:

1. Amendments to Credit Agreement.

(a) The definition of “Applicable Rate” in Section 1.01 of the Credit Agreement is hereby amended and restated to read in its entirety as follows:

“ ‘Applicable Rate’ means, for any day, with respect to: (a) any CBFR Loan, a per annum rate equal to zero percent (0.00%); (b) any Eurodollar Revolving Loan, a per annum rate equal to two and one half of one percent (2.50%); (c) any Canadian Prime Rate Loan, a per annum rate equal

to one percent (1.00%); and (d) any CDOR Rate Loan, a per annum rate equal to two and one half of one percent (2.50%).”

(b) Clause (a) of the definition of “Interest Period” in Section 1.01 of the Credit Agreement is hereby amended and restated to read in its entirety as follows:

“(a) any Eurodollar Borrowing, the period commencing on the date of such Borrowing and ending on the numerically corresponding day in the calendar month that is one, two, three or six months (or, with the consent of each U.S. Lender, twelve months) thereafter, as the Borrower Representative may elect, and”

(c) Section 6.08(iv)(A) of the Credit Agreement is hereby amended and restated to read in its entirety as follows:

“(A) the aggregate amount of such dividends and repurchases does not exceed: (x) $12,000,000 during any rolling 12 month period, and (y) $40,000,000 over the life of this Agreement (provided, that, no Loan Party shall be required to pay any fee to Administrative Agent or any Lender in connection with a request by the Loan Parties and the consent by the Required Lenders (which may be withheld in their sole discretion) to deviate from the forgoing limits in this Section 6.08(a)(iv));”

2. Conditions Precedent to Effectiveness of this Amendment. The following shall have occurred before this Amendment is effective:

3. Representations and Warranties. Each Borrower and each other Loan Party represents and warrants as follows:

2

4. Choice of Law. The validity of this Amendment, its construction, interpretation and enforcement, the rights of the parties hereunder, shall be determined under, governed by, and construed in accordance with the internal laws of the State of California, without giving effect to any conflict of law principles (but giving effect to Federal laws relating to national banks).

5. Counterparts. This Amendment may be executed in any number of counterparts and by different parties and separate counterparts, each of which when so executed and delivered, shall be deemed an original, and all of which, when taken together, shall constitute one and the same instrument. Delivery of an executed counterpart of a signature page to this Amendment by telefacsimile shall be effective as delivery of a manually executed counterpart of the Amendment.

6. Reference to and Effect on the Loan Documents.

7. Ratification. Each Borrower and each other Loan Party hereby restates, ratifies and reaffirms each and every term and condition set forth in the Credit Agreement, as amended hereby, and the Loan Documents effective as of the date hereof.

3

8. Estoppel. To induce Agents and Lenders to enter into this Amendment and to induce Agents and the Lenders to continue to make advances to Borrowers under the Credit Agreement, each Borrower and each other Loan Party hereby acknowledges and agrees that, after giving effect to this Amendment, as of the date hereof, there exists no Default or Event of Default and no right of offset, defense, counterclaim, or objection in favor of any Borrower or any other Loan Party as against any Agent or any Lender with respect to the Obligations.

9. Integration. This Amendment, together with the other Loan Documents, incorporates all negotiations of the parties hereto with respect to the subject mater hereof and is the final expression and agreement of the parties hereto with respect to the subject matter hereof.

10. Severability. In case any provision in this Amendment shall be invalid, illegal, or unenforceable, such provision shall be severable from the remainder of this Amendment and the validity, legality , and enforceability of the remaining provisions shall not in any way be affected or impaired thereby.

11. Submission of Amendment. The submission of this Amendment to the parties or their agents or attorneys for review or signature does not constitute a commitment by any Agent or any Lender to waive any of their respective rights and remedies under the Loan Documents, and this Amendment shall have no binding force or effect until all of the conditions to the effectiveness of this Amendment have been satisfied as set forth herein.

[REMAINDER OF PAGE LEFT INTENTIONALLY BLANK]

4

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed and delivered by their duly authorized officers as of the day and year first above written.

5

6