Document:

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                                                                    EXHIBIT 10.4

                                PROMISSORY NOTE

$12,273,650.11                                               September 2, 2001

      1.    Principal and Interest. MMC Technology, Inc. (the "Company"), a
California corporation, for value received, hereby promises to pay to the order
of Hynix Semiconductor America Inc. ("Payee") in lawful money of the United
States at the principal office of the Company, the principal sum of Twelve
Million Two Hundred Seventy Three Thousand Six Hundred Fifty Dollars and Eleven
Cents ($12,273,650.11), payable as follows:

      (a)   a principal amount of Five Million Dollars ($5,000,000.00) at the
closing of the transactions contemplated in the Agreement and Plan of
Reorganization dated as of August 17, 2001 to which the Company and the Payee
are each a party (the "Closing"); and

      (b)   following payment of the amount in Section 1(a), the outstanding
principal balance hereunder in the amount of Seven Million Two Hundred Seventy
Three Thousand Six Hundred Fifty Dollars and Eleven Cents ($7,273,650.11), on
or before March 31, 2002; provided, however, that in the event that the
principal amount set forth in this Section 1(b) is not paid in full on or before
March 31, 2002, such unpaid principal amount shall thereafter accrue interest at
a rate per annum equal to nine percent (9%) and all accrued and unpaid interest
shall be due and payable on demand by Payee. Except as expressly set forth in
this Section 1(b), this Promissory Note shall not bear any interest.

      2.    Attorneys' Fees. If the indebtedness represented by this Note or any
part thereof is the subject of an action in bankruptcy, receivership or other
judicial proceedings or if this Note is placed in the hands of attorneys for
collection after default, Company agrees to pay, in addition to the due and
unpaid principal and interest payable hereunder, reasonable and documented
attorneys' fees and reasonable and documented costs incurred by Payee.

      3.    Prepayment. The indebtedness represented by this Note may be
pre-paid by the Company at any time without penalty or any other charge or
assessment.

      4.    Acceleration. The indebtedness represented by this Note shall become
immediately due and payable if (i) the Company commences any proceeding in
bankruptcy or for dissolution, liquidation, winding-up, or other relief under
state or federal bankruptcy laws; or (ii) such proceedings are commenced against
the Company, or a receiver or trustee is appointed for the Company or a
substantial part of its property, and such proceeding or appointment is not
dismissed or discharged within 60 days after its commencement.

      5.    Waivers. Company hereby waives presentment, demand for performance,
notice of non-performance, protest, notice of protest and notice of dishonor. No
delay on the part of Payee in exercising any right hereunder shall operate as a
waiver of such right or any other right. This Note is being delivered in and
shall be construed in accordance with the laws of the State of California,
without regard to the conflicts of laws provisions hereof.

                                          MMC Technology, Inc.

                                          By:  /s/ TAJ GUILAMANI
                                             ----------------------------
                                          Its:  Taj Guilamani
                                              ---------------------------
                                                  VP Fin<PAGE>
                                                                    EXHIBIT 10.5

                                PROMISSORY NOTE

In consideration of the receipt of two million United States dollars
(U.S.$2,000,000.00) ("Principal"), Maker promises to pay to Holder on 12-31,
2001 ("Due Date") the entire Principal plus interest thereon accrued at the rate
of nine percent (9.0%) per year ("Interest") from the date hereof to the date of
payment (calculated by the actual over 360 method). Maker may prepay this note
in whole or in part at any time or times and such prepayment(s) shall be applied
first to any unpaid interest and then to any unpaid Principal. Maker waives
presentment, notice, waiver and all other defenses and acknowledges that this is
a general recourse obligation of Maker. This Promissory Note shall be subject to
and construed by the laws of California as they apply to obligations made and
performed therein by residents thereof.

DATE:  January 5, 2001

Hyundai Electronics America         ("Maker")

BY: /s/ Thomas J. Thomas
   --------------------------
PRINT:  Thomas J. Thomas
      -----------------------
TITLE:  V.P. Finance/CFO
      -----------------------

Accepted by:

Maxtor Corporation                  ("Holder")

BY:
   --------------------------
PRINT:
      -----------------------
TITLE:
      -----------------------<PAGE>
                                                                    EXHIBIT 10.1

                     SECURED FULL RECOURSE PROMISSORY NOTE

$5,875,000                                                         July 12, 2001
                                                            San Jose, California

     FOR VALUE RECEIVED, the undersigned KENNETH E. WESTRICK (the "Employee")
and KIRSTEN V. WESTRICK (jointly and severally, the "Borrowers"), promise to
pay to NEW FOCUS, INC., a Delaware corporation ("Lender"), at 5212 Hellyer
Avenue, San Jose, California 95138 (or at such other place as Lender may from
time to time designate by written notice to Borrower), in lawful money of the
United States, the principal sum of Five Million Eight Hundred Seventy-Five
Thousand Dollars ($5,875,000) plus interest, on the following terms:

     1.   PAYMENT:

          Upon the occurrence of a Maturity Event (as defined herein), the
entire principal amount of Five Million Eight Hundred Seventy-Five Thousand
Dollars ($5,875,000) and all allowed interest shall be immediately due and
payable in lawful money of the United States.

     2.   SECURITY: This Note is secured by a deed of trust of even date
herewith made by Borrowers, as trustors, to First American Title Insurance
Company, as trustee for Lender, as beneficiary (the "Deed of Trust"),
encumbering certain real property located in [*], [*] described on Exhibit A
attached hereto (the "Property").

     3.   MATURITY EVENT: Upon the occurrence of a Maturity Event (as
hereinafter defined), the entire principal amount of this Note and any other
sums due hereunder, shall become immediately due and payable without further
demand or notice to Borrowers. To the extent

                                       1

[*]  Certain information on this page has been omitted and filed separately with
     the Commission. Confidential treatment has been requested with respect to
     the omitted portions.

<PAGE>
permitted by law, any of the following events shall be a "Maturity Event" under
this Note and the Deed of Trust:

               (a) One Hundred Eighty (180) days after the date of termination
or cessation of Employee's employment with Lender for any reason; provided,
however, that if Employee's employment is terminated by Lender prior to December
31, 2001, the date of the Maturity Event shall be June 30, 2002.

               (b) There shall occur any default in the performance of any
obligation of Borrowers contained in the Deed of Trust, any other deed of trust
or mortgage encumbering the Property or any other deed of trust, security
agreement or other agreement (including any amendment, modification or extension
thereof) which may hereafter be executed by Borrowers for the purpose of
securing this Note.

               (c) Borrowers, without the prior written consent of Lender, sell,
convey, encumber, grant any lien upon or otherwise alienate the Property, or any
part thereof, or any interest therein, or are divested of their title or any
interest therein in any manner or way, whether voluntarily or involuntarily.

               (d) Either of the Borrowers (i) admits in writing his or her
inability to pay debts, (ii) makes an assignment for the benefit of creditors,
(iii) files a voluntary petition in bankruptcy, effects a plan or other
arrangement with creditors, liquidates assets under arrangement with creditors,
or liquidates his or her assets under court supervision, (iv) has an involuntary
petition in bankruptcy filed against him or her that is not discharged within
sixty (60) days after such petition is filed, or

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(v) applies for or permits the appointment of a receiver or trustee or
custodian for any of his or her property or assets which shall not have been
discharged within sixty (60) days after the date of appointment.

          (e)  July 11, 2004.

          (f)  Borrowers breach any representation or warranty contained herein
or in the Deed of Trust, or any statement or instrument executed in connection
with this Note proves to have been false or misleading.

          (g)  Borrowers fail to execute, acknowledge and deliver the Deed of
Trust concurrently with this Note.

          (h)  One Hundred Eighty (180) days after Employee's death.

     4.   INTEREST: Interest on the outstanding principal balance of this Note
shall accrue at the rate of Eight percent (8%) per annum for the first ninety
(90) days after the date of this Note and, unless Borrowers and Lender otherwise
agree in writing, Nine and 99/100 percent (9.99%) per annum thereafter. Upon the
failure of Borrowers to pay the outstanding principal balance after a Maturity
Event, interest on the outstanding principal balance shall thereafter accrue at
the rate of twelve percent (12%) per annum, or if lower, the highest rate
permitted by applicable law. Interest shall be calculated on the basis of a
three hundred sixty (360) day year consisting of twelve (12) months, and shall
compound annually.

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        5. BORROWER'S REPRESENTATIONS: Borrowers hereby make the following
representations and warranties to Lender and acknowledges that Lender is relying
on such representations in making the loan:

               (a) Borrowers have good and marketable title to the Property.

               (b) The consent of no other person or entity is required to grant
the security interest in the Property to Lender evidenced by the Deed of Trust.

               (c) To Borrower's knowledge, there are no material actions,
proceedings, claims or disputes pending or, to the Borrowers' knowledge,
threatened against or affecting the Borrowers or the Property other than
putative securities class actions filed against Lender and several of its
officers and directors, including Employee, and a shareholder derivative action
filed purportedly on behalf of Lender against several of its officers and
directors, including Employee.

        6. BORROWER'S ADDITIONAL OBLIGATIONS: Borrowers shall take any and all
further actions that may from time to time be required to ensure that the Deed
of Trust creates a valid lien on the Property, subject only to the First Deed of
Trust (defined below). If it should be hereafter determined that there are
defects against title or matters which could result in defects against title to
the Property, or that the consent of another person or entity is required to
grant to and perfect in Lender a valid second-priority lien on the Property,
Borrowers shall promptly take all action necessary to remove such defects and to
obtain such consent and grant (or cause to be granted) and perfect such lien on
the Property. Failure of Borrowers to comply with the provisions of this
Paragraph 6 shall be deemed a default under this Note and the Deed of Trust.

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     7.   DUE ON SALE: The Deed of Trust provides, among other things, as
follows:

     If the trustor shall sell, convey or otherwise alienate said property, or
any part thereof, or any interest therein, or shall be divested of the
trustor's title or any interest therein in any manner or way, whether
voluntarily or involuntarily, without the written consent of the beneficiary
being first had and obtained, in beneficiary's sole and absolute discretion,
beneficiary shall have the right, at its option, except as prohibited by law,
to declare any indebtedness or obligations secured hereby, irrespective of the
maturity date specified in the Note, immediately due and payable.

     8.   FIRST DEED OF TRUST: As used herein, "First Deed of Trust" shall mean
the deed of trust constituting a first-priority lien against the Property, by
Borrowers to Comerica Bank - California, as trustee, for the benefit of
Comerica Bank - California, as beneficiary, securing a loan in a principal
amount not in excess of Six Million Five Hundred Thousand Dollars ($6,500,000).

     9.   ATTORNEYS' FEES: In the event of Borrowers' default hereunder,
Borrowers shall pay all costs of collection, including reasonable attorneys'
fees incurred by the holder hereof on account of such collection, whether or
not suit is filed hereon.

     10.  WAIVER: The waiver by Lender of any breach of or default under any
term, covenant or condition contained herein or in any other agreement referred
to above shall not be deemed to be a waiver of any subsequent breach of or
default under the same or any other such term, covenant or condition.

     11.  NO USURY: Anything in this Note to the contrary notwithstanding, it
is expressly stipulated and agreed that the intent of Borrowers and Lender is
to comply at all times with all usury

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and other laws relating to this Note. If the laws of the State of California
would now or hereafter render usurious, or are revised, repealed or judicially
interpreted so as to render usurious, any amount called for under this Note, or
contracted for, charged or received with respect to the loan evidenced by this
Note, or if any prepayment by Borrowers results in Borrowers having paid any
interest in excess of that permitted by law, then it is Borrowers' and Lender's
express intent that all excess amounts theretofore collected by Lender be
credited to the principal balance of this Note (or, if this Note has been paid
in full, refunded to Borrowers), and the provisions of this Note immediately be
deemed reformed and the amounts therefor collectible hereunder reduced, without
the necessity of execution of any new document, so as to comply with the then
applicable law, but so as to permit the recovery of the fullest amount otherwise
called for hereunder.

     12.  PREPAYMENT: Borrowers may prepay all or any portion of this Note at
any time prior to the stated maturity date, with no premium or penalty.

     13.  NOTICE: This Note is subject to Sections 2924(i) and 2966 of the
California Civil Code which provides that the holder of this Note shall give
written notice to Borrowers or their successors-in-interest, of prescribed
information (as set forth in said Civil Code Sections) at least ninety (90) days
and not more than one hundred and fifty (150) days before any Balloon Payment is
due.

     14.  GENERAL PROVISIONS: This Note shall be governed by and construed in
accordance with the laws of the State of California. The maker of this Note
hereby waives presentment for payment, protest and demand, notice of protest,
demand and dishonor and nonpayment of this Note,

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and consents that Lender may extend the time for payment or otherwise modify the
terms of payment or any part of the whole of the debt evidenced by this Note, at
the request of any person liable hereon, and such consent shall not otherwise
alter nor diminish the liability of any person. Borrowers hereby waive the
defense of the statute of limitations in any action on this Note to the extent
permitted by law.

     15.  BORROWERS' ACKNOWLEDGEMENTS:

          (a)  Borrowers understand and acknowledge that this Note does not
modify Employee's at-will status at Lender and does not constitute an
employment agreement or a promise by Lender to continue Employee's employment.
Either Lender or Employee may terminate such employment relationship at any
time, with or without cause.

          (b)  Borrowers hereby acknowledge that Lender has made no
representation or warranty to Borrowers concerning the income tax consequences
of the loan to Borrowers and Borrowers shall be solely responsible for
ascertaining and bearing such tax consequences.

     16.  THIS NOTE, THE DEED OF TRUST, AND ALL RELATED DOCUMENTATION ARE
EXECUTED VOLUNTARILY AND WITHOUT ANY DURESS OR UNDUE INFLUENCE ON THE PART OF
OR ON BEHALF OF THE PARTIES HERETO, WITH THE FULL INTENT OF CREATING THE
OBLIGATIONS AND SECURITY INTEREST DESCRIBED HEREIN AND THEREIN. BORROWERS
ACKNOWLEDGE THAT: (a) THEY HAVE READ SUCH DOCUMENTATION; (b) THEY HAVE BEEN
REPRESENTED IN THE PREPARATION, NEGOTIATION AND EXECUTION OF SUCH DOCUMENTATION
BY LEGAL COUNSEL OF

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THEIR OWN CHOICE OR THAT THEY HAVE VOLUNTARILY DECLINED TO SEEK SUCH COUNSEL;
(c) THEY UNDERSTAND THE TERMS AND CONSEQUENCES OF THIS NOTE, THE DEED OF TRUST
AND ALL RELATED DOCUMENTATION AND THE OBLIGATIONS THEY CREATE; AND (d) THEY ARE
FULLY AWARE OF THE LEGAL AND BINDING EFFECT OF THIS NOTE, THE DEED OF TRUST AND
THE OTHER DOCUMENTS CONTEMPLATED BY THIS NOTE.

                                         AS BORROWERS:

                                         /s/ KENNETH E. WESTRICK
                                         --------------------------
                                         Kenneth E. Westrick

                                         /s/ KIRSTEN V. WESTRICK
                                         --------------------------
                                         Kirsten V. Westrick

                                       8
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                                   EXHIBIT A

                                  [*] PROPERTY

That certain real property located at    [*]     as more particularly described
in the Deed of Trust

[*]  Certain information on this page has been omitted and filed separately with
     the Commission. Confidential treatment has been requested with respect to
     the omitted portions.

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