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                                                                    Exhibit 10.6

                                 PROMISSORY NOTE



                                                         As of December 12, 2000


      1. FOR VALUE RECEIVED, Ken Levy U.S. Passport No.151375242 of 19800 Glen
            Una Drive, Saratoga, CA (address) (hereinafter referred to as the
            "MR. LEVY"), promises to pay to the order of SAIFUN SEMICONDUCTORS
            LTD. (hereinafter referred to as the "COMPANY"), having an address
            at Poleg Industrial Park, Netanya, Israel, the principal sum of $US
            250,000, together with all accrued and unpaid interest at a rate of
            six and one hundredths percent (6.01%) per year (the "DEBT").

      2. This Promissory Note, including the entire unpaid Debt represented
            hereby, is secured by all 60,000 ordinary shares of NIS 0.01 nominal
            value of the Company acquired by Mr. Levy from the Company as of the
            date hereof and shall become immediately due and payable, without
            notice or demand upon the earlier of (i) 5 years from the date,
            which the shares were granted to Mr. Levy ("SHARES"); or (ii) the
            Company's initial public offering; or (iii) 60 days from Mr. Levy's
            termination of rendering services to the Company (as defined in the
            Stock Purchase Agreement between the Company and Mr. Levy).

      3. Notwithstanding the foregoing, the Company shall hold the Shares in
            escrow under the terms of the Stock Purchase Agreement as a
            guarantee to secure the payment of the Debt of Mr. Ken Levy for the
            issuance of such Shares.

      4. Mr. Levy may at any time or from time to time make a voluntary
            prepayment, whether in full or in part of this Promissory Note.

      5. At the option of the Company, this Promissory Note and the entire
            unpaid indebtedness represented hereby shall become immediately due
            and payable, without notice or demand if Mr. Levy shall commence a
            case under the federal bankruptcy laws, or any state insolvency
            laws, or similar relief under any present or future statute, law or
            regulation.

      6. In addition to and not in limitation of the foregoing, Mr. Levy further
            agrees to pay all expenses, including reasonable attorney's fees and
            legal expenses, incurred by the Company in collecting or attempting
            to collect any amounts payable hereunder, which are not paid when
            due.

      7. No delay or omission or failure on the part of the Company in
            exercising any right hereunder and no partial or single exercise of
            that right shall operate as a waiver of such right or of any other
            right of the Company.
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      8. This Promissory Note shall be binding upon the undersigned and its
            successors and assigns. Any notice, demand or communication in
            respect of this Promissory Note shall be validly given, or made on,
            the undersigned if in writing and delivered or sent by registered
            mail, postage pre-paid, addressed to the undersigned at the address
            set forth above or at a subsequent business address of the
            undersigned.

      9. This Promissory Note and all rights and obligation hereunder,
            including matters of construction, validity and performance, shall
            be governed by the laws of the State of Israel.

      10. Any provision hereof, which may prove unenforceable under any law
            shall not affect the validity of any other provision hereof.

      11. This Promissory Note may not be changed or terminated orally, but only
            by a writing signed by the Company.

      12. Mr. Levy shall receive a credit against any interest otherwise due
            under this Promissory Note to the extent of any withholding taxes
            paid by Mr. Levy to the United States with respect to such interest.

      IN WITNESS WHEREOF, Mr. Levy has caused this Promissory Note to be
      executed in its name and behalf by its signatory thereunto duly authorized
      as of the date first above written.

                                        /s/ Ken Levy
                                        --------------------------------------
                                        MR. KEN LEVY




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